rfc9172.original   rfc9172.txt 
Delay-Tolerant Networking E. Birrane Internet Engineering Task Force (IETF) E. Birrane, III
Internet-Draft K. McKeever Request for Comments: 9172 K. McKeever
Intended status: Standards Track JHU/APL Category: Standards Track JHU/APL
Expires: August 19, 2021 February 15, 2021 ISSN: 2070-1721 January 2022
Bundle Protocol Security Specification Bundle Protocol Security (BPSec)
draft-ietf-dtn-bpsec-27
Abstract Abstract
This document defines a security protocol providing data integrity This document defines a security protocol providing data integrity
and confidentiality services for the Bundle Protocol. and confidentiality services for the Bundle Protocol (BP).
Status of This Memo Status of This Memo
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
1.1. Supported Security Services . . . . . . . . . . . . . . . 3 1.1. Supported Security Services
1.2. Specification Scope . . . . . . . . . . . . . . . . . . . 4 1.2. Specification Scope
1.3. Related Documents . . . . . . . . . . . . . . . . . . . . 5 1.3. Related Documents
1.4. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6 1.4. Terminology
2. Design Decisions . . . . . . . . . . . . . . . . . . . . . . 7 2. Design Decisions
2.1. Block-Level Granularity . . . . . . . . . . . . . . . . . 7 2.1. Block-Level Granularity
2.2. Multiple Security Sources . . . . . . . . . . . . . . . . 8 2.2. Multiple Security Sources
2.3. Mixed Security Policy . . . . . . . . . . . . . . . . . . 9 2.3. Mixed Security Policy
2.4. User-Defined Security Contexts . . . . . . . . . . . . . 9 2.4. User-Defined Security Contexts
2.5. Deterministic Processing . . . . . . . . . . . . . . . . 9 2.5. Deterministic Processing
3. Security Blocks . . . . . . . . . . . . . . . . . . . . . . . 10 3. Security Blocks
3.1. Block Definitions . . . . . . . . . . . . . . . . . . . . 10 3.1. Block Definitions
3.2. Uniqueness . . . . . . . . . . . . . . . . . . . . . . . 10 3.2. Uniqueness
3.3. Target Multiplicity . . . . . . . . . . . . . . . . . . . 12 3.3. Target Multiplicity
3.4. Target Identification . . . . . . . . . . . . . . . . . . 13 3.4. Target Identification
3.5. Block Representation . . . . . . . . . . . . . . . . . . 13 3.5. Block Representation
3.6. Abstract Security Block . . . . . . . . . . . . . . . . . 13 3.6. Abstract Security Block
3.7. Block Integrity Block . . . . . . . . . . . . . . . . . . 16 3.7. Block Integrity Block
3.8. Block Confidentiality Block . . . . . . . . . . . . . . . 17 3.8. Block Confidentiality Block
3.9. Block Interactions . . . . . . . . . . . . . . . . . . . 18 3.9. Block Interactions
3.10. Parameter and Result Identification . . . . . . . . . . . 19 3.10. Parameter and Result Identification
3.11. BSP Block Examples . . . . . . . . . . . . . . . . . . . 20 3.11. BPSec Block Examples
3.11.1. Example 1: Constructing a Bundle with Security . . . 20 3.11.1. Example 1: Constructing a Bundle with Security
3.11.2. Example 2: Adding More Security At A New Node . . . 21 3.11.2. Example 2: Adding More Security at a New Node
4. Canonical Forms . . . . . . . . . . . . . . . . . . . . . . . 23 4. Canonical Forms
5. Security Processing . . . . . . . . . . . . . . . . . . . . . 24 5. Security Processing
5.1. Bundles Received from Other Nodes . . . . . . . . . . . . 24 5.1. Bundles Received from Other Nodes
5.1.1. Receiving BCBs . . . . . . . . . . . . . . . . . . . 24 5.1.1. Receiving BCBs
5.1.2. Receiving BIBs . . . . . . . . . . . . . . . . . . . 25 5.1.2. Receiving BIBs
5.2. Bundle Fragmentation and Reassembly . . . . . . . . . . . 26 5.2. Bundle Fragmentation and Reassembly
6. Key Management . . . . . . . . . . . . . . . . . . . . . . . 27 6. Key Management
7. Security Policy Considerations . . . . . . . . . . . . . . . 27 7. Security Policy Considerations
7.1. Security Reason Codes . . . . . . . . . . . . . . . . . . 28 7.1. Security Reason Codes
8. Security Considerations . . . . . . . . . . . . . . . . . . . 30 8. Security Considerations
8.1. Attacker Capabilities and Objectives . . . . . . . . . . 30 8.1. Attacker Capabilities and Objectives
8.2. Attacker Behaviors and BPSec Mitigations . . . . . . . . 31 8.2. Attacker Behaviors and BPSec Mitigations
8.2.1. Eavesdropping Attacks . . . . . . . . . . . . . . . . 31 8.2.1. Eavesdropping Attacks
8.2.2. Modification Attacks . . . . . . . . . . . . . . . . 32 8.2.2. Modification Attacks
8.2.3. Topology Attacks . . . . . . . . . . . . . . . . . . 33 8.2.3. Topology Attacks
8.2.4. Message Injection . . . . . . . . . . . . . . . . . . 34 8.2.4. Message Injection
9. Security Context Considerations . . . . . . . . . . . . . . . 34 9. Security Context Considerations
9.1. Mandating Security Contexts . . . . . . . . . . . . . . . 34 9.1. Mandating Security Contexts
9.2. Identification and Configuration . . . . . . . . . . . . 35 9.2. Identification and Configuration
9.3. Authorship . . . . . . . . . . . . . . . . . . . . . . . 37 9.3. Authorship
10. Defining Other Security Blocks . . . . . . . . . . . . . . . 38 10. Defining Other Security Blocks
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 39 11. IANA Considerations
11.1. Bundle Block Types . . . . . . . . . . . . . . . . . . . 39 11.1. Bundle Block Types
11.2. Bundle Status Report Reason Codes . . . . . . . . . . . 40 11.2. Bundle Status Report Reason Codes
11.3. Security Context Identifiers . . . . . . . . . . . . . . 40 11.3. Security Context Identifiers
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 41 12. References
12.1. Normative References . . . . . . . . . . . . . . . . . . 41 12.1. Normative References
12.2. Informative References . . . . . . . . . . . . . . . . . 42 12.2. Informative References
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 42 Acknowledgments
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 42 Authors' Addresses
1. Introduction 1. Introduction
This document defines security features for the Bundle Protocol (BP) This document defines security features for the Bundle Protocol (BP)
[I-D.ietf-dtn-bpbis] and is intended for use in Delay Tolerant [RFC9171] and is intended for use in Delay-Tolerant Networking (DTN)
Networks (DTNs) to provide security services between a security to provide security services between a security source and a security
source and a security acceptor. When the security source is the acceptor. When the security source is the bundle source and the
bundle source and when the security acceptor is the bundle security acceptor is the bundle destination, the security service
destination, the security service provides end-to-end protection. provides end-to-end protection.
The Bundle Protocol specification [I-D.ietf-dtn-bpbis] defines DTN as The Bundle Protocol specification [RFC9171] defines DTN as referring
referring to "a networking architecture providing communications in to "a network architecture providing communications in and/or through
and/or through highly stressed environments" where "BP may be viewed highly stressed environments" where "BP may be viewed as sitting at
as sitting at the application layer of some number of constituent the application layer of some number of constituent networks, forming
networks, forming a store-carry-forward overlay network". The term a store-carry-forward overlay network". The phrase "stressed
"stressed" environment refers to multiple challenging conditions environment" refers to multiple challenging conditions including
including intermittent connectivity, large and/or variable delays, intermittent connectivity, large and/or variable delays, asymmetric
asymmetric data rates, and high bit error rates. data rates, and high bit error rates.
It should be presumed that the BP will be deployed such that the It should be presumed that the BP will be deployed in an untrusted
network cannot be trusted, posing the usual security challenges network, which poses the usual security challenges related to
related to confidentiality and integrity. However, the stressed confidentiality and integrity. However, the stressed nature of the
nature of the BP operating environment imposes unique conditions BP operating environment imposes unique conditions where usual
where usual transport security mechanisms may not be sufficient. For transport security mechanisms may not be sufficient. For example,
example, the store-carry-forward nature of the network may require the store-carry-forward nature of the network may require protecting
protecting data at rest, preventing unauthorized consumption of data at rest, preventing unauthorized consumption of critical
critical resources such as storage space, and operating without resources such as storage space, and operating without regular
regular contact with a centralized security oracle (such as a contact with a centralized security oracle (such as a certificate
certificate authority). authority).
An end-to-end security service is needed that operates in all of the An end-to-end security service that operates in all of the
environments where the BP operates. environments where the BP operates is needed.
1.1. Supported Security Services 1.1. Supported Security Services
BPSec provides integrity and confidentiality services for BP bundles, BPSec provides integrity and confidentiality services for BP bundles,
as defined in this section. as defined in this section.
Integrity services ensure that changes to target data within a bundle Integrity services ensure that changes to target data within a bundle
can be discovered. Data changes may be caused by processing errors, can be discovered. Data changes may be caused by processing errors,
environmental conditions, or intentional manipulation. In the environmental conditions, or intentional manipulation. In the
context of BPSec, integrity services apply to plain text in the context of BPSec, integrity services apply to plaintext in the
bundle. bundle.
Confidentiality services ensure that target data is unintelligible to Confidentiality services ensure that target data is unintelligible to
nodes in the DTN, except for authorized nodes possessing special nodes in DTN, except for authorized nodes possessing special
information. This generally means producing cipher text from plain information. Generally, this means producing ciphertext from
text and generating authentication information for that cipher text. plaintext and generating authentication information for that
Confidentiality, in this context, applies to the contents of target ciphertext. In this context, confidentiality applies to the contents
data and does not extend to hiding the fact that confidentiality of target data and does not extend to hiding the fact that
exists in the bundle. confidentiality exists in the bundle.
NOTE: Hop-by-hop authentication is NOT a supported security service NOTE: Hop-by-hop authentication is NOT a supported security service
in this specification, for two reasons. in this specification, for two reasons:
1. The term "hop-by-hop" is ambiguous in a BP overlay, as nodes that 1. The term "hop-by-hop" is ambiguous in a BP overlay, as nodes that
are adjacent in the overlay may not be adjacent in physical are adjacent in the overlay may not be adjacent in physical
connectivity. This condition is difficult or impossible to connectivity. This condition is difficult or impossible to
detect and therefore hop-by-hop authentication is difficult or detect; therefore, hop-by-hop authentication is difficult or
impossible to enforce. impossible to enforce.
2. Hop-by-hop authentication cannot be deployed in a network if 2. Hop-by-hop authentication cannot be deployed in a network if
adjacent nodes in the network have incompatible security adjacent nodes in the network have incompatible security
capabilities. capabilities.
1.2. Specification Scope 1.2. Specification Scope
This document defines the security services provided by the BPSec. This document defines the security services provided by the BPSec.
This includes the data specification for representing these services This includes the data specification for representing these services
as BP extension blocks, and the rules for adding, removing, and as BP extension blocks and the rules for adding, removing, and
processing these blocks at various points during the bundle's processing these blocks at various points during the bundle's
traversal of the DTN. traversal of a delay-tolerant network.
BPSec addresses only the security of data traveling over the DTN, not BPSec addresses only the security of data traveling over the DTN, not
the underlying DTN itself. Furthermore, while the BPSec protocol can the underlying DTN itself. Furthermore, while the BPSec protocol can
provide security-at-rest in a store-carry-forward network, it does provide security-at-rest in a store-carry-forward network, it does
not address threats which share computing resources with the DTN and/ not address threats that share computing resources with the DTN and/
or BPSec software implementations. These threats may be malicious or BPSec software implementations. These threats may be malicious
software or compromised libraries which intend to intercept data or software or compromised libraries that intend to intercept data or
recover cryptographic material. Here, it is the responsibility of recover cryptographic material. Here, it is the responsibility of
the BPSec implementer to ensure that any cryptographic material, the BPSec implementer to ensure that any cryptographic material,
including shared secret or private keys, is protected against access including shared secrets or private keys, is protected against access
within both memory and storage devices. within both memory and storage devices.
Completely trusted networks are extremely uncommon. Amongst Completely trusted networks are extremely uncommon. Among untrusted
untrusted networks, different networking conditions and operational networks, different networking conditions and operational
considerations require varying strengths of security mechanism. considerations require security mechanisms of varying strengths.
Mandating a single security context may result in too much security Mandating a single security context, which is a set of assumptions,
for some networks and too little security in others. It is expected algorithms, configurations, and policies used to implement security
that separate documents define different security contexts for use in services, may result in too much security for some networks and too
different networks. A set of default security contexts are defined little security in others. Default security contexts are defined in
in ([I-D.ietf-dtn-bpsec-default-sc]) and provide basic security [RFC9173] to provide basic security services for interoperability
services for interoperability testing and for operational use on the testing and for operational use on the terrestrial Internet. It is
terrestrial Internet. expected that separate documents will define different security
contexts for use in different networks.
This specification addresses neither the fitness of externally- This specification addresses neither the fitness of externally
defined cryptographic methods nor the security of their defined cryptographic methods nor the security of their
implementation. implementation.
This specification does not address the implementation of security This specification does not address the implementation of security
policy and does not provide a security policy for the BPSec. Similar policies and does not provide a security policy for the BPSec.
to cipher suites, security policies are based on the nature and Similar to cipher suites, security policies are based on the nature
capabilities of individual networks and network operational concepts. and capabilities of individual networks and network operational
This specification does provide policy considerations when building a concepts. This specification does provide policy considerations that
security policy. can be taken into account when building a security policy.
With the exception of the Bundle Protocol, this specification does With the exception of the Bundle Protocol, this specification does
not address how to combine the BPSec security blocks with other not address how to combine the BPSec security blocks with other
protocols, other BP extension blocks, or other best practices to protocols, other BP extension blocks, or other best practices to
achieve security in any particular network implementation. achieve security in any particular network implementation.
1.3. Related Documents 1.3. Related Documents
This document is best read and understood within the context of the This document is best read and understood within the context of the
following other DTN documents: following other DTN documents:
"Delay-Tolerant Networking Architecture" [RFC4838] defines the * "Delay-Tolerant Networking Architecture" [RFC4838] defines the
architecture for DTNs and identifies certain security assumptions architecture for DTN and identifies certain security assumptions
made by existing Internet protocols that are not valid in a DTN. made by existing Internet protocols that are not valid in DTN.
The Bundle Protocol [I-D.ietf-dtn-bpbis] defines the format and * "Bundle Protocol Version 7" [RFC9171] defines the format and
processing of bundles, defines the extension block format used to processing of bundles, the extension block format used to
represent BPSec security blocks, and defines the canonical block represent BPSec security blocks, and the canonical block structure
structure used by this specification. used by this specification.
The Concise Binary Object Representation (CBOR) format [RFC8949] * "Concise Binary Object Representation (CBOR)" [RFC8949] defines a
defines a data format that allows for small code size, fairly small data format that allows for small code size, fairly small message
message size, and extensibility without version negotiation. The size, and extensibility without version negotiation. The block-
block-specific-data associated with BPSec security blocks are encoded type-specific data associated with BPSec security blocks is
in this data format. encoded in this data format.
The Bundle Security Protocol [RFC6257] and Streamlined Bundle * "Bundle Security Protocol Specification" [RFC6257] introduces the
Security Protocol [I-D.birrane-dtn-sbsp] documents introduced the concept of using BP extension blocks for security services in DTN.
concepts of using BP extension blocks for security services in a DTN. BPSec is a continuation and refinement of this document.
The BPSec is a continuation and refinement of these documents.
1.4. Terminology 1.4. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
This section defines terminology either unique to the BPSec or This section defines terminology that either is unique to the BPSec
otherwise necessary for understanding the concepts defined in this or is necessary for understanding the concepts defined in this
specification. specification.
o Bundle Destination - the node which receives a bundle and delivers Bundle Destination: the Bundle Protocol Agent (BPA) that receives a
the payload of the bundle to an application. Also, the Node ID of bundle and delivers the payload of the bundle to an Application
the Bundle Protocol Agent (BPA) receiving the bundle. The bundle Agent. Also, an endpoint comprising the node(s) at which the
destination acts as the security acceptor for every security bundle is to be delivered. The bundle destination acts as the
target in every security block in every bundle it receives. security acceptor for every security target in every security
block in every bundle it receives.
o Bundle Source - the node which originates a bundle. Also, the Bundle Source: the BPA that originates a bundle. Also, any node ID
Node ID of the BPA originating the bundle. of the node of which the BPA is a component.
o Cipher Suite - a set of one or more algorithms providing integrity Cipher Suite: a set of one or more algorithms providing integrity
and/or confidentiality services. Cipher suites may define user and/or confidentiality services. Cipher suites may define user
parameters (e.g. secret keys to use) but do not provide values for parameters (e.g., secret keys to use), but they do not provide
those parameters. values for those parameters.
o Forwarder - any node that transmits a bundle in the DTN. Also, Forwarder: any BPA that transmits a bundle in DTN. Also, any node
the Node ID of the BPA that sent the bundle on its most recent ID of the node of which the BPA that sent the bundle on its most
hop. recent hop is a component.
o Intermediate Receiver, Waypoint, or Next Hop - any node that Intermediate Receiver, Waypoint, or Next Hop: any BPA that receives
receives a bundle from a Forwarder that is not the Bundle a bundle from a forwarder that is not the bundle destination.
Destination. Also, the Node ID of the BPA at any such node. Also, any node ID of the node of which the BPA is a component.
o Path - the ordered sequence of nodes through which a bundle passes Path: the ordered sequence of nodes through which a bundle passes on
on its way from Source to Destination. The path is not its way from source to destination. The path is not necessarily
necessarily known in advance by the bundle or any BPAs in the DTN. known in advance by the bundle or any BPAs in DTN.
o Security Acceptor - a bundle node that processes and dispositions Security Acceptor: a BPA that processes and dispositions one or more
one or more security blocks in a bundle. Security acceptors act security blocks in a bundle. Security acceptors act as the
as the endpoint of a security service represented in a security endpoint of a security service represented in a security block.
block. They remove the security blocks they act upon as part of They remove the security blocks they act upon as part of
processing and disposition. Also, the Node ID of that node. processing and disposition. Also, any node ID of the node of
which the BPA is a component.
o Security Block - a BPSec extension block in a bundle. Security Block: a BPSec extension block in a bundle.
o Security Context - the set of assumptions, algorithms, Security Context: the set of assumptions, algorithms,
configurations and policies used to implement security services. configurations, and policies used to implement security services.
o Security Operation - the application of a given security service Security Operation: the application of a given security service to a
to a security target, notated as OP(security service, security security target, notated as OP(security service, security target).
target). For example, OP(bcb-confidentiality, payload). Every For example, OP(bcb-confidentiality, payload). Every security
security operation in a bundle MUST be unique, meaning that a operation in a bundle MUST be unique, meaning that a given
given security service can only be applied to a security target security service can only be applied to a security target once in
once in a bundle. A security operation is implemented by a a bundle. A security operation is implemented by a security
security block. block.
o Security Service - a process that gives some protection to a Security Service: a process that gives some protection to a security
security target. For example, this specification defines security target. For example, this specification defines security services
services for plain text integrity (bib-integrity), and for plaintext integrity (bib-integrity) and authenticated
authenticated plain text confidentiality with additional plaintext confidentiality with additional authenticated data (bcb-
authenticated data (bcb-confidentiality). confidentiality).
o Security Source - a bundle node that adds a security block to a Security Source: a BPA that adds a security block to a bundle.
bundle. Also, the Node ID of that node. Also, any node ID of the node of which the BPA is a component.
o Security Target - the block within a bundle that receives a Security Target: the block within a bundle that receives a security
security service as part of a security operation. service as part of a security operation.
o Security Verifier - a bundle node that verifies the correctness of Security Verifier: a BPA that verifies the data integrity of one or
one or more security blocks in a bundle. Unlike security more security blocks in a bundle. Unlike security acceptors,
acceptors, security verifiers do not act as the endpoint of a security verifiers do not act as the endpoint of a security
security service and do not remove verified security blocks. service, and they do not remove verified security blocks. Also,
Also, the Node ID of that node. any node ID of the node of which the BPA is a component.
2. Design Decisions 2. Design Decisions
The application of security services in a DTN is a complex endeavor The application of security services in DTN is a complex endeavor
that must consider physical properties of the network (such as that must consider physical properties of the network (such as
connectivity and propagation times), policies at each node, connectivity and propagation times), policies at each node,
application security requirements, and current and future threat application security requirements, and current and future threat
environments. This section identifies those desirable properties environments. This section identifies those desirable properties
that guide design decisions for this specification and are necessary that guide design decisions for this specification and that are
for understanding the format and behavior of the BPSec protocol. necessary for understanding the format and behavior of the BPSec
protocol.
2.1. Block-Level Granularity 2.1. Block-Level Granularity
Security services within this specification must allow different Security services within this specification must allow different
blocks within a bundle to have different security services applied to blocks within a bundle to have different security services applied to
them. them.
Blocks within a bundle represent different types of information. The Blocks within a bundle represent different types of information. The
primary block contains identification and routing information. The primary block contains identification and routing information. The
payload block carries application data. Extension blocks carry a payload block carries application data. Extension blocks carry a
variety of data that may augment or annotate the payload, or variety of data that may augment or annotate the payload or that
otherwise provide information necessary for the proper processing of otherwise provide information necessary for the proper processing of
a bundle along a path. Therefore, applying a single level and type a bundle along a path. Therefore, applying a single level and type
of security across an entire bundle fails to recognize that blocks in of security across an entire bundle fails to recognize that blocks in
a bundle represent different types of information with different a bundle represent different types of information with different
security needs. security needs.
For example, a payload block might be encrypted to protect its For example, a payload block might be encrypted to protect its
contents and an extension block containing summary information contents and an extension block containing summary information
related to the payload might be integrity signed but unencrypted to related to the payload might be integrity signed but unencrypted to
provide waypoints access to payload-related data without providing provide waypoints access to payload-related data without providing
access to the payload. access to the payload.
2.2. Multiple Security Sources 2.2. Multiple Security Sources
A bundle can have multiple security blocks and these blocks can have A bundle can have multiple security blocks, and these blocks can have
different security sources. BPSec implementations MUST NOT assume different security sources. BPSec implementations MUST NOT assume
that all blocks in a bundle have the same security operations applied that all blocks in a bundle have the same security operations applied
to them. to them.
The Bundle Protocol allows extension blocks to be added to a bundle The Bundle Protocol allows extension blocks to be added to a bundle
at any time during its existence in the DTN. When a waypoint adds a at any time during its existence in DTN. When a waypoint adds a new
new extension block to a bundle, that extension block MAY have extension block to a bundle, that extension block MAY have security
security services applied to it by that waypoint. Similarly, a services applied to it by that waypoint. Similarly, a waypoint MAY
waypoint MAY add a security service to an existing block, consistent add a security service to an existing block, consistent with its
with its security policy. security policy.
When a waypoint adds a security service to the bundle, the waypoint When a waypoint adds a security service to the bundle, the waypoint
is the security source for that service. The security block(s) which is the security source for that service. The security block(s) that
represent that service in the bundle may need to record this security represent that service in the bundle may need to record this security
source as the bundle destination might need this information for source, as the bundle destination might need this information for
processing. processing.
For example, a bundle source may choose to apply an integrity service For example, a bundle source may choose to apply an integrity service
to its plain text payload. Later a waypoint node, representing a to its plaintext payload. Later a waypoint node, representing a
gateway to another portion of the DTN, may receive the bundle and gateway to another portion of the delay-tolerant network, may receive
choose to apply a confidentiality service. In this case, the the bundle and choose to apply a confidentiality service. In this
integrity security source is the bundle source and the case, the integrity security source is the bundle source and the
confidentiality security source is the waypoint node. confidentiality security source is the waypoint node.
In cases where the security source and security acceptor are not the In cases where the security source and security acceptor are not the
bundle source and bundle destination, it is possible that the bundle bundle source and bundle destination, respectively, it is possible
will reach the bundle destination prior to reaching a security that the bundle will reach the bundle destination prior to reaching a
acceptor. In cases where this may be a practical problem, it is security acceptor. In cases where this may be a practical problem,
recommended that solutions such as bundle encapsulation can be used it is recommended that solutions such as bundle encapsulation be used
to ensure that a bundle be delivered to a security acceptor prior to to ensure that a bundle be delivered to a security acceptor prior to
being delivered to the bundle destination. Generally, if a bundle being delivered to the bundle destination. Generally, if a bundle
reaches a waypoint that has the appropriate configuration and policy reaches a waypoint that has the appropriate configuration and policy
to act as a security acceptor for a security service in the bundle, to act as a security acceptor for a security service in the bundle,
then the waypoint should act as that security acceptor. then the waypoint should act as that security acceptor.
2.3. Mixed Security Policy 2.3. Mixed Security Policy
The security policy enforced by nodes in the DTN may differ. The security policy enforced by nodes in the delay-tolerant network
may differ.
Some waypoints will have security policies that require evaluating Some waypoints will have security policies that require the waypoint
security services even if they are not the bundle destination or the to evaluate security services even if the waypoint is neither the
final intended acceptor of the service. For example, a waypoint bundle destination nor the final intended acceptor of the service.
could choose to verify an integrity service even though the waypoint For example, a waypoint could choose to verify an integrity service
is not the bundle destination and the integrity service will be even though the waypoint is not the bundle destination and the
needed by other nodes along the bundle's path. integrity service will be needed by other nodes along the bundle's
path.
Some waypoints will determine, through policy, that they are the Some waypoints will determine, through policy, that they are the
intended recipient of the security service and terminate the security intended recipient of the security service and will terminate the
service in the bundle. For example, a gateway node could determine security service in the bundle. For example, a gateway node could
that, even though it is not the destination of the bundle, it should determine that, even though it is not the destination of the bundle,
verify and remove a particular integrity service or attempt to it should verify and remove a particular integrity service or attempt
decrypt a confidentiality service, before forwarding the bundle along to decrypt a confidentiality service, before forwarding the bundle
its path. along its path.
Some waypoints could understand security blocks but refuse to process Some waypoints could understand security blocks but refuse to process
them unless they are the bundle destination. them unless they are the bundle destination.
2.4. User-Defined Security Contexts 2.4. User-Defined Security Contexts
A security context is the union of security algorithms (cipher A security context is the set of assumptions, algorithms,
suites), policies associated with the use of those algorithms, and configurations, and policies used to implement security services.
configuration values. Different contexts may specify different Different contexts may specify different algorithms, different
algorithms, different polices, or different configuration values used polices, or different configuration values used in the implementation
in the implementation of their security services. BPSec provides a of their security services. BPSec provides a mechanism to define
mechanism to define security contexts. Users may select from security contexts. Users may select from registered security
registered security contexts and customize those contexts through contexts and customize those contexts through security context
security context parameters. parameters.
For example, some users might prefer a SHA2 hash function for For example, some users might prefer a SHA2 hash function for
integrity whereas other users might prefer a SHA3 hash function. integrity, whereas other users might prefer a SHA3 hash function.
Providing either separate security contexts or a single, Providing either separate security contexts or a single,
parameterized security context allows users flexibility in applying parameterized security context allows users flexibility in applying
the desired cipher suite, policy, and configuration when populating a the desired cipher suite, policy, and configuration when populating a
security block. security block.
2.5. Deterministic Processing 2.5. Deterministic Processing
Whenever a node determines that it must process more than one Whenever a node determines that it must process more than one
security block in a received bundle (either because the policy at a security block in a received bundle (either because the policy at a
waypoint states that it should process security blocks or because the waypoint states that it should process security blocks or because the
node is the bundle destination) the order in which security blocks node is the bundle destination), the order in which security blocks
are processed must be deterministic. All nodes must impose this same are processed must be deterministic. All nodes must impose this same
deterministic processing order for all security blocks. This deterministic processing order for all security blocks. This
specification provides determinism in the application and evaluation specification provides determinism in the application and evaluation
of security services, even when doing so results in a loss of of security services, even when doing so results in a loss of
flexibility. flexibility.
3. Security Blocks 3. Security Blocks
3.1. Block Definitions 3.1. Block Definitions
This specification defines two types of security block: the Block This specification defines two types of security block: the Block
Integrity Block (BIB) and the Block Confidentiality Block (BCB). Integrity Block (BIB) and the Block Confidentiality Block (BCB).
The BIB is used to ensure the integrity of its plain text security * The BIB is used to ensure the integrity of its plaintext security
target(s). The integrity information in the BIB MAY be verified target(s). The integrity information in the BIB MAY be verified
by any node along the bundle path from the BIB security source to by any node along the bundle path from the BIB security source to
the bundle destination. Waypoints add or remove BIBs from bundles the bundle destination. Waypoints add or remove BIBs from bundles
in accordance with their security policy. BIBs are never used for in accordance with their security policy. BIBs are never used for
integrity protection of the cipher text provided by a BCB. integrity protection of the ciphertext provided by a BCB. Because
Because security policy at BPSec nodes may differ regarding security policy at BPSec nodes may differ regarding integrity
integrity verification, BIBs do not guarantee hop-by-hop verification, BIBs do not guarantee hop-by-hop authentication, as
authentication, as discussed in Section 1.1. discussed in Section 1.1.
The BCB indicates that the security target(s) have been encrypted * The BCB indicates that the security target or targets have been
at the BCB security source in order to protect their content while encrypted at the BCB security source in order to protect their
in transit. The BCB is decrypted by security acceptor nodes in content while in transit. As a matter of security policy, the BCB
the network, up to and including the bundle destination, as a is decrypted by security acceptor nodes in the network, up to and
matter of security policy. BCBs additionally provide integrity including the bundle destination. BCBs additionally provide
protection mechanisms for the cipher text they generate. integrity-protection mechanisms for the ciphertext they generate.
3.2. Uniqueness 3.2. Uniqueness
Security operations in a bundle MUST be unique; the same security Security operations in a bundle MUST be unique; the same security
service MUST NOT be applied to a security target more than once in a service MUST NOT be applied to a security target more than once in a
bundle. Since a security operation is represented by a security bundle. Since a security operation is represented by a security
block, this means that multiple security blocks of the same type block, this means that multiple security blocks of the same type
cannot share the same security targets. A new security block MUST cannot share the same security targets. A new security block MUST
NOT be added to a bundle if a pre-existing security block of the same NOT be added to a bundle if a preexisting security block of the same
type is already defined for the security target of the new security type is already defined for the security target of the new security
block. block.
This uniqueness requirement ensures that there is no ambiguity This uniqueness requirement ensures that there is no ambiguity
related to the order in which security blocks are processed or how related to the order in which security blocks are processed or how
security policy can be specified to require certain security services security policy can be specified to require certain security services
be present in a bundle. be present in a bundle.
Using the notation OP(service, target), several examples illustrate Using the notation OP(service, target), several examples illustrate
this uniqueness requirement. this uniqueness requirement.
o Signing the payload twice: The two operations OP(bib-integrity, Signing the payload twice: The two operations OP(bib-integrity,
payload) and OP(bib-integrity, payload) are redundant and MUST NOT payload) and OP(bib-integrity, payload) are redundant and MUST NOT
both be present in the same bundle at the same time. both be present in the same bundle at the same time.
o Signing different blocks: The two operations OP(bib-integrity, Signing different blocks: The two operations OP(bib-integrity,
payload) and OP(bib-integrity, extension_block_1) are not payload) and OP(bib-integrity, extension_block_1) are not
redundant and both may be present in the same bundle at the same redundant and both may be present in the same bundle at the same
time. Similarly, the two operations OP(bib-integrity, time. Similarly, the two operations OP(bib-integrity,
extension_block_1) and OP(bib-integrity, extension_block_2) are extension_block_1) and OP(bib-integrity, extension_block_2) are
also not redundant and may both be present in the bundle at the also not redundant and may both be present in the bundle at the
same time. same time.
o Different Services on same block: The two operations OP(bib- Different services on same block: The two operations OP(bib-
integrity, payload) and OP(bcb-confidentiality, payload) are not integrity, payload) and OP(bcb-confidentiality, payload) are not
inherently redundant and may both be present in the bundle at the inherently redundant and may both be present in the bundle at the
same time, pursuant to other processing rules in this same time, pursuant to other processing rules in this
specification. specification.
o Different services from different block types: The notation Different services from different block types: The notation
OP(service, target) refers specifically to a security block, as OP(service, target) refers specifically to a security block, as
the security block is the embodiment of a security service applied the security block is the embodiment of a security service applied
to a security target in a bundle. Were some Other Security Block to a security target in a bundle. Were some Other Security Block
(OSB) to be defined providing an integrity service, then the (OSB) to be defined providing an integrity service, then the
operations OP(bib-integrity, target) and OP(osb-integrity, target) operations OP(bib-integrity, target) and OP(osb-integrity, target)
MAY both be present in the same bundle if so allowed by the MAY both be present in the same bundle if so allowed by the
definition of the OSB, as discussed in Section 10. definition of the OSB, as discussed in Section 10.
NOTES: NOTES:
A security block may be removed from a bundle as part of security * A security block may be removed from a bundle as part of security
processing at a waypoint node with a new security block being processing at a waypoint node with a new security block being
added to the bundle by that node. In this case, conflicting added to the bundle by that node. In this case, conflicting
security blocks never co-exist in the bundle at the same time and security blocks never coexist in the bundle at the same time and
the uniqueness requirement is not violated. the uniqueness requirement is not violated.
A cipher text integrity mechanism (such as associated * A ciphertext integrity-protection mechanism (such as associated
authenticated data) calculated by a cipher suite and transported authenticated data) calculated by a cipher suite and transported
in a BCB is considered part of the confidentiality service and, in a BCB is considered part of the confidentiality service;
therefore, unique from the plain text integrity service provided therefore, it is unique from the plaintext integrity service
by a BIB. provided by a BIB.
The security blocks defined in this specification (BIB and BCB) * The security blocks defined in this specification (BIB and BCB)
are designed with the intention that the BPA adding these blocks are designed with the intention that the BPA adding these blocks
is the authoritative source of the security service. If a BPA is the authoritative source of the security service. If a BPA
adds a BIB on a security target, then the BIB is expected to be adds a BIB on a security target, then the BIB is expected to be
the authoritative source of integrity for that security target. the authoritative source of integrity for that security target.
If a BPA adds a BCB to a security target, then the BCB is expected If a BPA adds a BCB to a security target, then the BCB is expected
to be the authoritative source of confidentiality for that to be the authoritative source of confidentiality for that
security target. More complex scenarios, such as having multiple security target. More complex scenarios, such as having multiple
nodes in a network sign the same security target, can be nodes in a network sign the same security target, can be
accommodated using the definition of custom security contexts accommodated using the definition of custom security contexts (see
(Section 9) and/or the definition of other security blocks Section 9) and/or the definition of OSBs (see Section 10).
(Section 10).
3.3. Target Multiplicity 3.3. Target Multiplicity
A single security block MAY represent multiple security operations as A single security block MAY represent multiple security operations as
a way of reducing the overall number of security blocks present in a a way of reducing the overall number of security blocks present in a
bundle. In these circumstances, reducing the number of security bundle. In these circumstances, reducing the number of security
blocks in the bundle reduces the amount of redundant information in blocks in the bundle reduces the amount of redundant information in
the bundle. the bundle.
A set of security operations can be represented by a single security A set of security operations can be represented by a single security
block when all of the following conditions are true. block when all of the following conditions are true.
o The security operations apply the same security service. For * The security operations apply the same security service. For
example, they are all integrity operations or all confidentiality example, they are all integrity operations or all confidentiality
operations. operations.
o The security context parameters for the security operations are * The security context parameters for the security operations are
identical. identical.
o The security source for the security operations is the same, * The security source for the security operations is the same,
meaning the set of operations are being added by the same node. meaning the set of operations are being added by the same node.
o No security operations have the same security target, as that * No security operations have the same security target, as that
would violate the need for security operations to be unique. would violate the need for security operations to be unique.
o None of the security operations conflict with security operations * None of the security operations conflict with security operations
already present in the bundle. already present in the bundle.
When representing multiple security operations in a single security When representing multiple security operations in a single security
block, the information that is common across all operations is block, the information that is common across all operations is
represented once in the security block, and the information which is represented once in the security block; the information that is
different (e.g., the security targets) are represented individually. different (e.g., the security targets) is represented individually.
It is RECOMMENDED that if a node processes any security operation in If a node processes any security operation in a security block, it is
a security block that it process all security operations in the RECOMMENDED that it process all security operations in the security
security block. This allows security sources to assert that the set block. This allows security sources to assert that the set of
of security operations in a security block are expected to be security operations in a security block are expected to be processed
processed by the same security acceptor. However, the determination by the same security acceptor. However, the determination of whether
of whether a node actually is a security acceptor or not is a matter a node actually is a security acceptor or not is a matter of the
of the policy of the node itself. In cases where a receiving node policy of the node itself. In cases where a receiving node
determines that it is the security acceptor of only a subset of the determines that it is the security acceptor of only a subset of the
security operations in a security block, the node may choose to only security operations in a security block, the node may choose to only
process that subset of security operations. process that subset of security operations.
3.4. Target Identification 3.4. Target Identification
A security target is a block in the bundle to which a security A security target is a block in the bundle to which a security
service applies. This target must be uniquely and unambiguously service applies. This target must be uniquely and unambiguously
identifiable when processing a security block. The definition of the identifiable when processing a security block. The definition of the
extension block header from [I-D.ietf-dtn-bpbis] provides a "Block extension block header from [RFC9171] provides a "block number" field
Number" field suitable for this purpose. Therefore, a security suitable for this purpose. Therefore, a security target in a
target in a security block MUST be represented as the Block Number of security block MUST be represented as the block number of the target
the target block. block.
3.5. Block Representation 3.5. Block Representation
Each security block uses the Canonical Bundle Block Format as defined Each security block uses the Canonical Bundle Block Format as defined
in [I-D.ietf-dtn-bpbis]. That is, each security block is comprised in [RFC9171]. That is, each security block is comprised of the
of the following elements: following elements:
o block type code
o block number
o block processing control flags
o CRC type
o block-type-specific-data
o CRC field (if present) * block type code
* block number
* block processing control flags
* cyclic redundancy check (CRC) type
* block-type-specific data
* CRC field (if present)
Security-specific information for a security block is captured in the Security-specific information for a security block is captured in the
block-type-specific-data field. block-type-specific data field.
3.6. Abstract Security Block 3.6. Abstract Security Block
The structure of the security-specific portions of a security block The structure of the security-specific portions of a security block
is identical for both the BIB and BCB Block Types. Therefore, this is identical for both the BIB and BCB block types. Therefore, this
section defines an Abstract Security Block (ASB) data structure and section defines an Abstract Security Block (ASB) data structure and
discusses the definition, processing, and other constraints for using discusses its definition, its processing, and other constraints for
this structure. An ASB is never directly instantiated within a using this structure. An ASB is never directly instantiated within a
bundle, it is only a mechanism for discussing the common aspects of bundle, it is only a mechanism for discussing the common aspects of
BIB and BCB security blocks. BIB and BCB security blocks.
The fields of the ASB SHALL be as follows, listed in the order in The fields of the ASB SHALL be as follows, listed in the order in
which they must appear. The encoding of these fields MUST be in which they must appear. The encoding of these fields MUST be in
accordance with the canonical forms provided in Section 4. accordance with the canonical forms provided in Section 4.
Security Targets: Security Targets:
This field identifies the block(s) targeted by the security This field identifies the block(s) targeted by the security
operation(s) represented by this security block. Each target operation(s) represented by this security block. Each target
block is represented by its unique Block Number. This field block is represented by its unique block number. This field
SHALL be represented by a CBOR array of data items. Each SHALL be represented by a Concise Binary Object Representation
target within this CBOR array SHALL be represented by a CBOR (CBOR) array of data items. Each target within this CBOR array
unsigned integer. This array MUST have at least 1 entry and SHALL be represented by a CBOR unsigned integer. This array
each entry MUST represent the Block Number of a block that MUST have at least one entry and each entry MUST represent the
exists in the bundle. There MUST NOT be duplicate entries in block number of a block that exists in the bundle. There MUST
this array. The order of elements in this list has no semantic NOT be duplicate entries in this array. The order of elements
meaning outside of the context of this block. Within the in this list has no semantic meaning outside of the context of
block, the ordering of targets must match the ordering of this block. Within the block, the ordering of targets must
results associated with these targets. match the ordering of results associated with these targets.
Security Context Id: Security Context Id:
This field identifies the security context used to implement This field identifies the security context used to implement
the security service represented by this block and applied to the security service represented by this block and applied to
each security target. This field SHALL be represented by a each security target. This field SHALL be represented by a
CBOR unsigned integer. The values for this Id should come from CBOR unsigned integer. The values for this Id should come from
the registry defined in Section 11.3 the registry defined in Section 11.3.
Security Context Flags: Security Context Flags:
This field identifies which optional fields are present in the This field identifies which optional fields are present in the
security block. This field SHALL be represented as a CBOR security block. This field SHALL be represented as a CBOR
unsigned integer whose contents shall be interpreted as a bit unsigned integer whose contents shall be interpreted as a bit
field. Each bit in this bit field indicates the presence (bit field. Each bit in this bit field indicates the presence (bit
set to 1) or absence (bit set to 0) of optional data in the set to 1) or absence (bit set to 0) of optional data in the
security block. The association of bits to security block data security block. The association of bits to security block data
is defined as follows. is defined as follows.
Bit 0 (the least-significant bit, 0x01): Security Context Bit 0 (the least-significant bit, 0x01): "Security context
Parameters Present Flag. parameters present" flag.
Bit >0 Reserved Bit >0 Reserved
Implementations MUST set reserved bits to 0 when writing this Implementations MUST set reserved bits to 0 when writing this
field and MUST ignore the values of reserved bits when reading field and MUST ignore the values of reserved bits when reading
this field. For unreserved bits, a value of 1 indicates that this field. For unreserved bits, a value of 1 indicates that
the associated security block field MUST be included in the the associated security block field MUST be included in the
security block. A value of 0 indicates that the associated security block. A value of 0 indicates that the associated
security block field MUST NOT be in the security block. security block field MUST NOT be in the security block.
Security Source: Security Source:
This field identifies the Endpoint that inserted the security This field identifies the BPA that inserted the security block
block in the bundle. This field SHALL be represented by a CBOR in the bundle. Also, any node ID of the node of which the BPA
array in accordance with [I-D.ietf-dtn-bpbis] rules for is a component. This field SHALL be represented by a CBOR
representing Endpoint Identifiers (EIDs). array in accordance with the rules in [RFC9171] for
representing endpoint IDs (EIDs).
Security Context Parameters (Optional): Security Context Parameters (Optional):
This field captures one or more security context parameters This field captures one or more security context parameters
that should be used when processing the security service that should be used when processing the security service
described by this security block. This field SHALL be described by this security block. This field SHALL be
represented by a CBOR array. Each entry in this array is a represented by a CBOR array. Each entry in this array is a
single security context parameter. A single parameter SHALL single security context parameter. A single parameter SHALL
also be represented as a CBOR array comprising a 2-tuple of the also be represented as a CBOR array comprising a 2-tuple of the
id and value of the parameter, as follows. Id and value of the parameter, as follows.
* Parameter Id. This field identifies which parameter is Parameter Id: This field identifies which parameter is being
being specified. This field SHALL be represented as a CBOR specified. This field SHALL be represented as a CBOR
unsigned integer. Parameter Ids are selected as described unsigned integer. Parameter Ids are selected as described
in Section 3.10. in Section 3.10.
* Parameter Value. This field captures the value associated Parameter Value: This field captures the value associated with
with this parameter. This field SHALL be represented by the this parameter. This field SHALL be represented by the
applicable CBOR representation of the parameter, in applicable CBOR representation of the parameter, in
accordance with Section 3.10. accordance with Section 3.10.
The logical layout of the parameters array is illustrated in The logical layout of the parameters array is illustrated in
Figure 1. Figure 1.
+----------------+----------------+ +----------------+ +----------------+----------------+ +----------------+
| Parameter 1 | Parameter 2 | ... | Parameter N | | Parameter 1 | Parameter 2 | ... | Parameter N |
+------+---------+------+---------+ +------+---------+ +------+---------+------+---------+ +------+---------+
| Id | Value | Id | Value | | Id | Value | | Id | Value | Id | Value | | Id | Value |
+------+---------+------+---------+ +------+---------+ +------+---------+------+---------+ +------+---------+
Figure 1: Security Context Parameters Figure 1: Security Context Parameters
Security Results: Security Results:
This field captures the results of applying a security service This field captures the results of applying a security service
to the security targets of the security block. This field to the security targets of the security block. This field
SHALL be represented as a CBOR array of target results. Each SHALL be represented as a CBOR array of target results. Each
entry in this array represents the set of security results for entry in this array represents the set of security results for
a specific security target. The target results MUST be ordered a specific security target. The target results MUST be ordered
identically to the Security Targets field of the security identically to the Security Targets field of the security
block. This means that the first set of target results in this block. This means that the first set of target results in this
array corresponds to the first entry in the Security Targets array corresponds to the first entry in the Security Targets
field of the security block, and so on. There MUST be one field of the security block, and so on. There MUST be one
entry in this array for each entry in the Security Targets entry in this array for each entry in the Security Targets
field of the security block. field of the security block.
The set of security results for a target is also represented as The set of security results for a target is also represented as
a CBOR array of individual results. An individual result is a CBOR array of individual results. An individual result is
represented as a 2-tuple of a result id and a result value, represented as a CBOR array comprising a 2-tuple of a result Id
defined as follows. and a result value, defined as follows.
* Result Id. This field identifies which security result is Result Id: This field identifies which security result is
being specified. Some security results capture the primary being specified. Some security results capture the primary
output of a cipher suite. Other security results contain output of a cipher suite. Other security results contain
additional annotative information from cipher suite additional annotative information from cipher suite
processing. This field SHALL be represented as a CBOR processing. This field SHALL be represented as a CBOR
unsigned integer. Security result Ids will be as specified unsigned integer. Security result Ids will be as specified
in Section 3.10. in Section 3.10.
* Result Value. This field captures the value associated with Result Value: This field captures the value associated with
the result. This field SHALL be represented by the the result. This field SHALL be represented by the
applicable CBOR representation of the result value, in applicable CBOR representation of the result value, in
accordance with Section 3.10. accordance with Section 3.10.
The logical layout of the security results array is illustrated The logical layout of the security results array is illustrated
in Figure 2. In this figure there are N security targets for in Figure 2. In this figure, there are N security targets for
this security block. The first security target contains M this security block. The first security target contains M
results and the Nth security target contains K results. results and the Nth security target contains K results.
+------------------------------+ +------------------------------+ +--------------------------+ +---------------------------+
| Target 1 | | Target N | | Target 1 | | Target N |
+------------+----+------------+ +------------------------------+ +----------+----+----------+ +---------------------------+
| Result 1 | | Result M | ... | Result 1 | | Result K | | Result 1 | | Result M | ... | Result 1 | | Result K |
+----+-------+ .. +----+-------+ +----+-------+ .. +----+-------+ +----+-----+ .. +----+-----+ +---+------+ .. +----+------+
| Id | Value | | Id | Value | | Id | Value | | Id | Value | | Id |Value| | Id |Value| | Id |Value| | Id | Value|
+----+-------+ +----+-------+ +----+-------+ +----+-------+ +----+-----+ +----+-----+ +----+-----+ +----+------+
Figure 2: Security Results Figure 2: Security Results
3.7. Block Integrity Block 3.7. Block Integrity Block
A BIB is a bundle extension block with the following characteristics. A BIB is a BP extension block with the following characteristics.
The Block Type Code value is as specified in Section 11.1. * The block type code value is as specified in Section 11.1.
The block-type-specific-data field follows the structure of the * The block-type-specific data field follows the structure of the
ASB. ASB.
A security target listed in the Security Targets field MUST NOT * A security target listed in the Security Targets field MUST NOT
reference a security block defined in this specification (e.g., a reference a security block defined in this specification (e.g., a
BIB or a BCB). BIB or a BCB).
The Security Context MUST utilize an authentication mechanism or * The security context MUST utilize an authentication mechanism or
an error detection mechanism. an error detection mechanism.
Notes: Notes:
o Designers SHOULD carefully consider the effect of setting flags * Designers SHOULD carefully consider the effect of setting flags
that either discard the block or delete the bundle in the event that either discard the block or delete the bundle in the event
that this block cannot be processed. that this block cannot be processed.
o Since OP(bib-integrity, target) is allowed only once in a bundle * Since OP(bib-integrity, target) is allowed only once in a bundle
per target, it is RECOMMENDED that users wishing to support per target, it is RECOMMENDED that users wishing to support
multiple integrity mechanisms for the same target define a multi- multiple integrity-protection mechanisms for the same target
result security context. Such a context could generate multiple define a multi-result security context. Such a context could
security results for the same security target using different generate multiple security results for the same security target
integrity-protection mechanisms or different configurations for using different integrity-protection mechanisms or different
the same integrity-protection mechanism. configurations for the same integrity-protection mechanism.
o A BIB is used to verify the plain text integrity of its security * A BIB is used to verify the plaintext integrity of its security
target. However, a single BIB MAY include security results for target. However, a single BIB MAY include security results for
blocks other than its security target when doing so establishes a blocks other than its security target when doing so establishes a
needed relationship between the BIB security target and other needed relationship between the BIB security target and other
blocks in the bundle (such as the primary block). blocks in the bundle (such as the primary block).
o Security information MAY be checked at any hop on the way to the * Security information MAY be checked at any hop on the way to the
bundle destination that has access to the required keying bundle destination that has access to the required keying
information, in accordance with Section 3.9. information, in accordance with Section 3.9.
3.8. Block Confidentiality Block 3.8. Block Confidentiality Block
A BCB is a bundle extension block with the following characteristics. A BCB is a BP extension block with the following characteristics.
The Block Type Code value is as specified in Section 11.1. * The block type code value is as specified in Section 11.1.
The Block Processing Control flags value can be set to whatever * The block processing control flags value can be set to whatever
values are required by local policy with the following exceptions. values are required by local policy with the following exceptions:
BCB blocks MUST have the "block must be replicated in every
fragment" flag set if one of the targets is the payload block.
Having that BCB in each fragment indicates to a receiving node
that the payload portion of each fragment represents cipher text.
BCB blocks MUST NOT have the "block must be removed from bundle if
it can't be processed" flag set. Removing a BCB from a bundle
without decrypting its security targets removes information from
the bundle necessary for their later decryption.
The block-type-specific-data fields follow the structure of the - BCBs MUST have the "Block must be replicated in every fragment"
flag set if one of the targets is the payload block. Having
that BCB in each fragment indicates to a receiving node that
the payload portion of each fragment represents ciphertext.
- BCBs MUST NOT have the "Block must be removed from bundle if it
can't be processed" flag set. Removing a BCB from a bundle
without decrypting its security targets removes information
from the bundle necessary for their later decryption.
* The block-type-specific data fields follow the structure of the
ASB. ASB.
A security target listed in the Security Targets field can * A security target listed in the Security Targets field can
reference the payload block, a non-security extension block, or a reference the payload block, a non-security extension block, or a
BIB. A BCB MUST NOT include another BCB as a security target. A BIB. A BCB MUST NOT include another BCB as a security target. A
BCB MUST NOT target the primary block. A BCB MUST NOT target a BCB MUST NOT target the primary block. A BCB MUST NOT target a
BIB block unless it shares a security target with that BIB block. BIB unless it shares a security target with that BIB.
Any Security Context used by a BCB MUST utilize a confidentiality * Any security context used by a BCB MUST utilize a confidentiality
cipher that provides authenticated encryption with associated data cipher that provides authenticated encryption with associated data
(AEAD). (AEAD).
Additional information created by a cipher suite (such as an * Additional information created by a cipher suite (such as an
authentication tag) can be placed either in a security result authentication tag) can be placed either in a security result
field or in the generated cipher text. The determination of where field or in the generated ciphertext. The determination of where
to place this information is a function of the cipher suite and to place this information is a function of the cipher suite and
security context used. security context used.
The BCB modifies the contents of its security target(s). When a BCB The BCB modifies the contents of its security target(s). When a BCB
is applied, the security target body data are encrypted "in-place". is applied, the security target body data are encrypted "in-place".
Following encryption, the security target block-type-specific-data Following encryption, the security target block-type-specific data
field contains cipher text, not plain text. field contains ciphertext, not plaintext.
Notes: Notes:
o It is RECOMMENDED that designers carefully consider the effect of * It is RECOMMENDED that designers carefully consider the effect of
setting flags that delete the bundle in the event that this block setting flags that delete the bundle in the event that this block
cannot be processed. cannot be processed.
o The BCB block processing control flags can be set independently * The BCB block processing control flags can be set independently
from the processing control flags of the security target(s). The from the processing control flags of the security target(s). The
setting of such flags should be an implementation/policy decision setting of such flags should be an implementation/policy decision
for the encrypting node. for the encrypting node.
3.9. Block Interactions 3.9. Block Interactions
The security block types defined in this specification are designed The security block types defined in this specification are designed
to be as independent as possible. However, there are some cases to be as independent as possible. However, there are some cases
where security blocks may share a security target creating processing where security blocks may share a security target; this sharing
dependencies. creates processing dependencies.
If a security target of a BCB is also a security target of a BIB, an If a BCB and a BIB share a security target, an undesirable condition
undesirable condition occurs where a waypoint would be unable to occurs: a waypoint would be unable to validate the BIB because the
validate the BIB because one of its security target's contents have shared security target has been encrypted by the BCB. To address
been encrypted by a BCB. To address this situation the following this situation, the following processing rules MUST be followed:
processing rules MUST be followed.
o When adding a BCB to a bundle, if some (or all) of the security * When adding a BCB to a bundle, if some (or all) of the security
targets of the BCB also match all of the security targets of an targets of the BCB match all of the security targets of an
existing BIB, then the existing BIB MUST also be encrypted. This existing BIB, then the existing BIB MUST also be encrypted. This
can be accomplished by either adding a new BCB that targets the can be accomplished either by adding a new BCB that targets the
existing BIB, or by adding the BIB to the list of security targets existing BIB or by adding the BIB to the list of security targets
for the BCB. Deciding which way to represent this situation is a for the BCB. Deciding which way to represent this situation is a
matter of security policy. matter of security policy.
o When adding a BCB to a bundle, if some (or all) of the security * When adding a BCB to a bundle, if some (or all) of the security
targets of the BCB match some (but not all) of the security targets of the BCB match some (but not all) of the security
targets of a BIB then that BIB MUST be altered in the following targets of a BIB, then that BIB MUST be altered in the following
way. Any security results in the BIB associated with the BCB way. Any security results in the BIB associated with the BCB
security targets MUST be removed from the BIB and placed in a new security targets MUST be removed from the BIB and placed in a new
BIB. This newly created BIB MUST then be encrypted. The BIB. This newly created BIB MUST then be encrypted. The
encryption of the new BIB can be accomplished by either adding a encryption of the new BIB can be accomplished either by adding a
new BCB that targets the new BIB, or by adding the new BIB to the new BCB that targets the new BIB or by adding the new BIB to the
list of security targets for the BCB. Deciding which way to list of security targets for the BCB. Deciding which way to
represent this situation is a matter of security policy. represent this situation is a matter of security policy.
o A BIB MUST NOT be added for a security target that is already the * A BIB MUST NOT be added for a security target that is already the
security target of a BCB as this would cause ambiguity in block security target of a BCB as this would cause ambiguity in block
processing order. processing order.
o A BIB integrity value MUST NOT be checked if the BIB is the * A BIB integrity value MUST NOT be checked if the BIB is the
security target of an existing BCB. In this case, the BIB data is security target of an existing BCB. In this case, the BIB data is
encrypted. encrypted.
o A BIB integrity value MUST NOT be checked if the security target * A BIB integrity value MUST NOT be checked if the security target
associated with that value is also the security target of a BCB. associated with that value is also the security target of a BCB.
In such a case, the security target data contains cipher text as In such a case, the security target data contains ciphertext as it
it has been encrypted. has been encrypted.
o As mentioned in Section 3.7, a BIB MUST NOT have a BCB as its * As mentioned in Section 3.7, a BIB MUST NOT have a BCB as its
security target. security target.
These restrictions on block interactions impose a necessary ordering These restrictions on block interactions impose a necessary ordering
when applying security operations within a bundle. Specifically, for when applying security operations within a bundle. Specifically, for
a given security target, BIBs MUST be added before BCBs. This a given security target, BIBs MUST be added before BCBs. This
ordering MUST be preserved in cases where the current BPA is adding ordering MUST be preserved in cases where the current BPA is adding
all of the security blocks for the bundle or whether the BPA is a all of the security blocks for the bundle or where the BPA is a
waypoint adding new security blocks to a bundle that already contains waypoint adding new security blocks to a bundle that already contains
security blocks. security blocks.
In cases where a security source wishes to calculate both a plain In cases where a security source wishes to calculate both a plaintext
text integrity mechanism and encrypt a security target, a BCB with a integrity-protection mechanism and encrypt a security target, a BCB
security context that generates an integrity-protection mechanism as with a security context that generates an integrity-protection
one or more additional security results MUST be used instead of mechanism as one or more additional security results MUST be used
adding both a BIB and then a BCB for the security target at the instead of adding both a BIB and then a BCB for the security target
security source. at the security source.
3.10. Parameter and Result Identification 3.10. Parameter and Result Identification
Each security context MUST define its own context parameters and Each security context MUST define its own context parameters and
results. Each defined parameter and result is represented as the results. Each defined parameter and result is represented as the
tuple of an identifier and a value. Identifiers are always tuple of an identifier and a value. Identifiers are always
represented as a CBOR unsigned integer. The CBOR encoding of values represented as a CBOR unsigned integer. The CBOR encoding of values
is as defined by the security context specification. is as defined by the security context specification.
Identifiers MUST be unique for a given security context but do not Identifiers MUST be unique for a given security context but do not
need to be unique amongst all security contexts. need to be unique amongst all security contexts.
An example of a security context can be found at An example of a security context can be found in [RFC9173].
[I-D.ietf-dtn-bpsec-default-sc].
3.11. BSP Block Examples 3.11. BPSec Block Examples
This section provides two examples of BPSec blocks applied to a This section provides two examples of BPSec blocks applied to
bundle. In the first example, a single node adds several security bundles. In the first example, a single node adds several security
operations to a bundle. In the second example, a waypoint node operations to a bundle. In the second example, a waypoint node
received the bundle created in the first example and adds additional received the bundle created in the first example and adds additional
security operations. In both examples, the first column represents security operations. In both examples, the first column represents
blocks within a bundle and the second column represents the Block blocks within a bundle and the second column represents the block
Number for the block, using the terminology B1...Bn for the purpose number for the block, using the terminology B1...Bn for the purpose
of illustration. of illustration.
3.11.1. Example 1: Constructing a Bundle with Security 3.11.1. Example 1: Constructing a Bundle with Security
In this example a bundle has four non-security-related blocks: the In this example, a bundle has four non-security-related blocks: the
primary block (B1), two extension blocks (B4,B5), and a payload block primary block (B1), two extension blocks (B4, B5), and a payload
(B6). The bundle source wishes to provide an integrity signature of block (B6). The bundle source wishes to provide an integrity
the plain text associated with the primary block, the second signature of the plaintext associated with the primary block, the
extension block, and the payload. The bundle source also wishes to second extension block, and the payload. The bundle source also
provide confidentiality for the first extension block. The resultant wishes to provide confidentiality for the first extension block. The
bundle is illustrated in Figure 3 and the security actions are resultant bundle is illustrated in Figure 3 and the security actions
described below. are described below.
Block in Bundle ID Block in Bundle ID
+==========================================+====+ +==========================================+====+
| Primary Block | B1 | | Primary Block | B1 |
+------------------------------------------+----+ +------------------------------------------+----+
| BIB | B2 | | BIB | B2 |
| OP(bib-integrity, targets=B1, B5, B6) | | | OP(bib-integrity, targets = B1, B5, B6)| |
+------------------------------------------+----+ +------------------------------------------+----+
| BCB | B3 | | BCB | B3 |
| OP(bcb-confidentiality, target=B4) | | | OP(bcb-confidentiality, target = B4) | |
+------------------------------------------+----+ +------------------------------------------+----+
| Extension Block (encrypted) | B4 | | Extension Block (encrypted) | B4 |
+------------------------------------------+----+ +------------------------------------------+----+
| Extension Block | B5 | | Extension Block | B5 |
+------------------------------------------+----+ +------------------------------------------+----+
| Payload Block | B6 | | Payload Block | B6 |
+------------------------------------------+----+ +------------------------------------------+----+
Figure 3: Security at Bundle Creation Figure 3: Security at Bundle Creation
The following security actions were applied to this bundle at its The following security actions were applied to this bundle at its
time of creation. time of creation.
o An integrity signature applied to the canonical form of the * An integrity signature applied to the canonical form of the
primary block (B1), the canonical form of the block-type-specific- primary block (B1), the canonical form of the block-type-specific
data field of the second extension block (B5) and the canonical data field of the second extension block (B5), and the canonical
form of the payload block (B6). This is accomplished by a single form of the payload block (B6). This is accomplished by a single
BIB (B2) with multiple targets. A single BIB is used in this case BIB (B2) with multiple targets. A single BIB is used in this case
because all three targets share a security source, security because all three targets share a security source, security
context, and security context parameters. Had this not been the context, and security context parameters. Had this not been the
case, multiple BIBs could have been added instead. case, multiple BIBs could have been added instead.
o Confidentiality for the first extension block (B4). This is * Confidentiality for the first extension block (B4). This is
accomplished by a BCB (B3). Once applied, the block-type- accomplished by a BCB (B3). Once applied, the block-type-specific
specific-data field of extension block B4 is encrypted. The BCB data field of extension block B4 is encrypted. The BCB MUST hold
MUST hold an authentication tag for the cipher text either in the an authentication tag for the ciphertext either in the ciphertext
cipher text that now populates the first extension block or as a that now populates the first extension block or as a security
security result in the BCB itself, depending on which security result in the BCB itself, depending on which security context is
context is used to form the BCB. A plain text integrity signature used to form the BCB. A plaintext integrity signature may also
may also exist as a security result in the BCB if one is provided exist as a security result in the BCB if one is provided by the
by the selected confidentiality security context. selected confidentiality security context.
3.11.2. Example 2: Adding More Security At A New Node 3.11.2. Example 2: Adding More Security at a New Node
Consider that the bundle as it is illustrated in Figure 3 is now Consider that the bundle as it is illustrated in Figure 3 is now
received by a waypoint node that wishes to encrypt the second received by a waypoint node that wishes to encrypt the second
extension block and the bundle payload. The waypoint security policy extension block and the bundle payload. The waypoint security policy
is to allow existing BIBs for these blocks to persist, as they may be is to allow existing BIBs for these blocks to persist, as they may be
required as part of the security policy at the bundle destination. required as part of the security policy at the bundle destination.
The resultant bundle is illustrated in Figure 4 and the security The resultant bundle is illustrated in Figure 4 and the security
actions are described below. Note that block IDs provided here are actions are described below. Note that block IDs provided here are
ordered solely for the purpose of this example and not meant to ordered solely for the purpose of this example and are not meant to
impose an ordering for block creation. The ordering of blocks added impose an ordering for block creation. The ordering of blocks added
to a bundle MUST always be in compliance with [I-D.ietf-dtn-bpbis]. to a bundle MUST always be in compliance with [RFC9171].
Block in Bundle ID Block in Bundle ID
+==========================================+====+ +==========================================+====+
| Primary Block | B1 | | Primary Block | B1 |
+------------------------------------------+----+ +------------------------------------------+----+
| BIB | B2 | | BIB | B2 |
| OP(bib-integrity, targets=B1) | | | OP(bib-integrity, target = B1) | |
+------------------------------------------+----+ +------------------------------------------+----+
| BIB (encrypted) | B7 | | BIB (encrypted) | B7 |
| OP(bib-integrity, targets=B5, B6) | | | OP(bib-integrity, targets = B5, B6) | |
+------------------------------------------+----+ +------------------------------------------+----+
| BCB | B8 | | BCB | B8 |
| OP(bcb-confidentiality,targets=B5,B6,B7) | | |OP(bcb-confidentiality,targets = B5,B6,B7)| |
+------------------------------------------+----+ +------------------------------------------+----+
| BCB | B3 | | BCB | B3 |
| OP(bcb-confidentiality, target=B4) | | | OP(bcb-confidentiality, target = B4) | |
+------------------------------------------+----+ +------------------------------------------+----+
| Extension Block (encrypted) | B4 | | Extension Block (encrypted) | B4 |
+------------------------------------------+----+ +------------------------------------------+----+
| Extension Block (encrypted) | B5 | | Extension Block (encrypted) | B5 |
+------------------------------------------+----+ +------------------------------------------+----+
| Payload Block (encrypted) | B6 | | Payload Block (encrypted) | B6 |
+------------------------------------------+----+ +------------------------------------------+----+
Figure 4: Security At Bundle Forwarding Figure 4: Security at Bundle Forwarding
The following security actions were applied to this bundle prior to The following security actions were applied to this bundle prior to
its forwarding from the waypoint node. its forwarding from the waypoint node.
o Since the waypoint node wishes to encrypt the block-type-specific- * Since the waypoint node wishes to encrypt the block-type-specific
data field of blocks B5 and B6, it MUST also encrypt the block- data field of blocks B5 and B6, it MUST also encrypt the block-
type-specific-data field of the BIBs providing plain text type-specific data field of the BIBs providing plaintext integrity
integrity over those blocks. However, BIB B2 could not be over those blocks. However, BIB B2 could not be encrypted in its
encrypted in its entirety because it also held a signature for the entirety because it also held a signature for the primary block
primary block (B1). Therefore, a new BIB (B7) is created and (B1). Therefore, a new BIB (B7) is created and security results
security results associated with B5 and B6 are moved out of BIB B2 associated with B5 and B6 are moved out of BIB B2 and into BIB B7.
and into BIB B7.
o Now that there is no longer confusion of which plain text * Now that there is no longer confusion about which plaintext
integrity signatures must be encrypted, a BCB is added to the integrity signatures must be encrypted, a BCB is added to the
bundle with the security targets being the second extension block bundle with the security targets being the second extension block
(B5) and the payload (B6) as well as the newly created BIB holding (B5) and the payload (B6) as well as the newly created BIB holding
their plain text integrity signatures (B7). A single new BCB is their plaintext integrity signatures (B7). A single new BCB is
used in this case because all three targets share a security used in this case because all three targets share a security
source, security context, and security context parameters. Had source, security context, and security context parameters. Had
this not been the case, multiple BCBs could have been added this not been the case, multiple BCBs could have been added
instead. instead.
4. Canonical Forms 4. Canonical Forms
Security services require consistency and determinism in how Security services require consistency and determinism in how
information is presented to cipher suites at security sources, information is presented to cipher suites at security sources,
verifiers, and acceptors. For example, integrity services require verifiers, and acceptors. For example, integrity services require
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algorithms transcode the contents of a security target into a algorithms transcode the contents of a security target into a
canonical form. canonical form.
Canonical forms are used to generate input to a security context for Canonical forms are used to generate input to a security context for
security processing at a BP node. If the values of a security target security processing at a BP node. If the values of a security target
are unchanged, then the canonical form of that target will be the are unchanged, then the canonical form of that target will be the
same even if the encoding of those values for wire transmission is same even if the encoding of those values for wire transmission is
different. different.
BPSec operates on data fields within bundle blocks (e.g., the block- BPSec operates on data fields within bundle blocks (e.g., the block-
type-specific-data field). In their canonical form, these fields type-specific data field). In their canonical form, these fields
MUST include their own CBOR encoding and MUST NOT include any other MUST include their own CBOR encoding and MUST NOT include any other
encapsulating CBOR encoding. For example, the canonical form of the encapsulating CBOR encoding. For example, the canonical form of the
block-type-specific-data field is a CBOR byte string existing within block-type-specific data field is a CBOR byte string existing within
the CBOR array containing the fields of the extension block. The the CBOR array containing the fields of the extension block. The
entire CBOR byte string is considered the canonical block-type- entire CBOR byte string is considered the canonical block-type-
specific-data field. The CBOR array framing is not considered part specific data field. The CBOR array framing is not considered part
of the field. of the field.
The canonical form of the primary block is as specified in The canonical form of the primary block is as specified in [RFC9171]
[I-D.ietf-dtn-bpbis] with the following constraint. with the following constraint.
o CBOR values from the primary block MUST be canonicalized using the * CBOR values from the primary block MUST be canonicalized using the
rules for Deterministically Encoded CBOR, as specified in rules for Deterministically Encoded CBOR, as specified in
[RFC8949]. [RFC8949].
All non-primary blocks share the same block structure and are All non-primary blocks share the same block structure and are
canonicalized as specified in [I-D.ietf-dtn-bpbis] with the following canonicalized as specified in [RFC9171] with the following
constraints. constraints.
o CBOR values from the non-primary block MUST be canonicalized using * CBOR values from the non-primary block MUST be canonicalized using
the rules for Deterministically Encoded CBOR, as specified in the rules for Deterministically Encoded CBOR, as specified in
[RFC8949]. [RFC8949].
o Only the block-type-specific-data field may be provided to a * Only the block-type-specific data field may be provided to a
cipher suite for encryption as part of a confidentiality security cipher suite for encryption as part of a confidentiality security
service. Other fields within a non-primary-block MUST NOT be service. Other fields within a non-primary block MUST NOT be
encrypted or decrypted and MUST NOT be included in the canonical encrypted or decrypted and MUST NOT be included in the canonical
form used by the cipher suite for encryption and decryption. form used by the cipher suite for encryption and decryption. An
These other fields MAY have an integrity protection mechanism integrity-protection mechanism MAY be applied to these other
applied to them by treating them as associated authenticated data. fields as supported by the security context. For example, these
fields might be treated as associated authenticated data.
o Reserved and unassigned flags in the block processing control * Reserved and unassigned flags in the block processing control
flags field MUST be set to 0 in a canonical form as it is not flags field MUST be set to 0 in a canonical form as it is not
known if those flags will change in transit. known if those flags will change in transit.
Security contexts MAY define their own canonicalization algorithms Security contexts MAY define their own canonicalization algorithms
and require the use of those algorithms over the ones provided in and require the use of those algorithms over the ones provided in
this specification. In the event of conflicting canonicalization this specification. In the event of conflicting canonicalization
algorithms, algorithms defined in a security context take precedence algorithms, algorithms defined in a security context take precedence
over this specification when constructing canonical forms for that over this specification when constructing canonical forms for that
security context. security context.
5. Security Processing 5. Security Processing
This section describes the security aspects of bundle processing. This section describes the security aspects of bundle processing.
5.1. Bundles Received from Other Nodes 5.1. Bundles Received from Other Nodes
Security blocks must be processed in a specific order when received Security blocks must be processed in a specific order when received
by a BP node. The processing order is as follows. by a BP node. The processing order is as follows.
o When BIBs and BCBs share a security target, BCBs MUST be evaluated * When BIBs and BCBs share a security target, BCBs MUST be evaluated
first and BIBs second. first and BIBs second.
5.1.1. Receiving BCBs 5.1.1. Receiving BCBs
If a received bundle contains a BCB, the receiving node MUST If a received bundle contains a BCB, the receiving node MUST
determine whether it is the security acceptor for any of the security determine whether it is the security acceptor for any of the security
operations in the BCB. If so, the node MUST process those operations operations in the BCB. If so, the node MUST process those operations
and remove any operation-specific information from the BCB prior to and remove any operation-specific information from the BCB prior to
delivering data to an application at the node or forwarding the delivering data to an application at the node or forwarding the
bundle. If processing a security operation fails, the target SHALL bundle. If processing a security operation fails, the target SHALL
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If the security policy of a node specifies that a node should have If the security policy of a node specifies that a node should have
applied confidentiality to a specific security target and no such BCB applied confidentiality to a specific security target and no such BCB
is present in the bundle, then the node MUST process this security is present in the bundle, then the node MUST process this security
target in accordance with the security policy. It is RECOMMENDED target in accordance with the security policy. It is RECOMMENDED
that the node remove the security target from the bundle because the that the node remove the security target from the bundle because the
confidentiality (and possibly the integrity) of the security target confidentiality (and possibly the integrity) of the security target
cannot be guaranteed. If the removed security target is the payload cannot be guaranteed. If the removed security target is the payload
block, the bundle MUST be discarded. block, the bundle MUST be discarded.
If an encrypted payload block cannot be decrypted (i.e., the cipher If an encrypted payload block cannot be decrypted (i.e., the
text cannot be authenticated), then the bundle MUST be discarded and ciphertext cannot be authenticated), then the bundle MUST be
processed no further. If an encrypted security target other than the discarded and processed no further. If an encrypted security target
payload block cannot be decrypted then the associated security target other than the payload block cannot be decrypted, then the associated
and all security blocks associated with that target MUST be discarded security target and all security blocks associated with that target
and processed no further. In both cases, requested status reports MUST be discarded and processed no further. In both cases, requested
(see [I-D.ietf-dtn-bpbis]) MAY be generated to reflect bundle or status reports (see [RFC9171]) MAY be generated to reflect bundle or
block deletion. block deletion.
When a BCB is decrypted, the recovered plain text for each security When a BCB is decrypted, the recovered plaintext for each security
target MUST replace the cipher text in each of the security targets' target MUST replace the ciphertext in each of the security targets'
block-type-specific-data fields. If the plain text is of different block-type-specific data fields. If the plaintext is of a different
size than the cipher text, the CBOR byte string framing of this field size than the ciphertext, the framing of the CBOR byte string of this
must be updated to ensure this field remains a valid CBOR byte field must be updated to ensure this field remains a valid CBOR byte
string. The length of the recovered plain text is known by the string. The length of the recovered plaintext is known by the
decrypting security context. decrypting security context.
If a BCB contains multiple security operations, each operation If a BCB contains multiple security operations, each operation
processed by the node MUST be treated as if the security operation processed by the node MUST be treated as if the security operation
has been represented by a single BCB with a single security operation has been represented by a single BCB with a single security operation
for the purposes of report generation and policy processing. for the purposes of report generation and policy processing.
5.1.2. Receiving BIBs 5.1.2. Receiving BIBs
If a received bundle contains a BIB, the receiving node MUST If a received bundle contains a BIB, the receiving node MUST
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bundle. If processing a security operation fails, the target SHALL bundle. If processing a security operation fails, the target SHALL
be processed according to the security policy. A bundle status be processed according to the security policy. A bundle status
report indicating the failure MAY be generated. When all security report indicating the failure MAY be generated. When all security
operations for a BIB have been removed from the BIB, the BIB MUST be operations for a BIB have been removed from the BIB, the BIB MUST be
removed from the bundle. removed from the bundle.
A BIB MUST NOT be processed if the security target of the BIB is also A BIB MUST NOT be processed if the security target of the BIB is also
the security target of a BCB in the bundle. Given the order of the security target of a BCB in the bundle. Given the order of
operations mandated by this specification, when both a BIB and a BCB operations mandated by this specification, when both a BIB and a BCB
share a security target, it means that the security target must have share a security target, it means that the security target must have
been encrypted after it was integrity signed and, therefore, the BIB been encrypted after it was integrity signed; therefore, the BIB
cannot be verified until the security target has been decrypted by cannot be verified until the security target has been decrypted by
processing the BCB. processing the BCB.
If the security policy of a node specifies that a node should have If the security policy of a node specifies that a node should have
applied integrity to a specific security target and no such BIB is applied integrity to a specific security target and no such BIB is
present in the bundle, then the node MUST process this security present in the bundle, then the node MUST process this security
target in accordance with the security policy. It is RECOMMENDED target in accordance with the security policy. It is RECOMMENDED
that the node remove the security target from the bundle if the that the node remove the security target from the bundle if the
security target is not the payload or primary block. If the security security target is not the payload or primary block. If the security
target is the payload or primary block, the bundle MAY be discarded. target is the payload or primary block, the bundle MAY be discarded.
This action can occur at any node that has the ability to verify an This action can occur at any node that has the ability to verify an
integrity signature, not just the bundle destination. integrity signature, not just the bundle destination.
If a receiving node is not the security acceptor of a security If a receiving node is not the security acceptor of a security
operation in a BIB it MAY attempt to verify the security operation operation in a BIB, it MAY attempt to verify the security operation
anyway to prevent forwarding corrupt data. If the verification anyway to prevent forwarding corrupt data. If the verification
fails, the node SHALL process the security target in accordance to fails, the node SHALL process the security target in accordance with
local security policy. It is RECOMMENDED that if a payload integrity local security policy. If a payload integrity check fails at a
check fails at a waypoint that it is processed in the same way as if waypoint, it is RECOMMENDED that it be processed in the same way as a
the check fails at the bundle destination. If the check passes, the failure of a payload integrity check at the bundle destination. If
node MUST NOT remove the security operation from the BIB prior to the check passes, the node MUST NOT remove the security operation
forwarding. from the BIB prior to forwarding.
If a BIB contains multiple security operations, each operation If a BIB contains multiple security operations, each operation
processed by the node MUST be treated as if the security operation processed by the node MUST be treated as if the security operation
has been represented by a single BIB with a single security operation has been represented by a single BIB with a single security operation
for the purposes of report generation and policy processing. for the purposes of report generation and policy processing.
5.2. Bundle Fragmentation and Reassembly 5.2. Bundle Fragmentation and Reassembly
If it is necessary for a node to fragment a bundle payload, and If it is necessary for a node to fragment a bundle payload, and
security services have been applied to that bundle, the fragmentation security services have been applied to that bundle, the fragmentation
rules described in [I-D.ietf-dtn-bpbis] MUST be followed. As defined rules described in [RFC9171] MUST be followed. As defined there and
there and summarized here for completeness, only the payload block summarized here for completeness, only the payload block can be
can be fragmented; security blocks, like all extension blocks, can fragmented; security blocks, like all extension blocks, can never be
never be fragmented. fragmented.
Due to the complexity of payload block fragmentation, including the Due to the complexity of payload-block fragmentation, including the
possibility of fragmenting payload block fragments, integrity and possibility of fragmenting payload-block fragments, integrity and
confidentiality operations are not to be applied to a bundle confidentiality operations are not to be applied to a bundle
representing a fragment. Specifically, a BCB or BIB MUST NOT be representing a fragment. Specifically, a BCB or BIB MUST NOT be
added to a bundle if the "Bundle is a Fragment" flag is set in the added to a bundle if the "Bundle is a fragment" flag is set in the
Bundle Processing Control Flags field. bundle processing control flags field.
Security processing in the presence of payload block fragmentation Security processing in the presence of payload-block fragmentation
may be handled by other mechanisms outside of the BPSec protocol or may be handled by other mechanisms outside of the BPSec protocol or
by applying BPSec blocks in coordination with an encapsulation by applying BPSec blocks in coordination with an encapsulation
mechanism. A node should apply any confidentiality protection prior mechanism. A node should apply any confidentiality protection prior
to performing any fragmentation. to performing any fragmentation.
6. Key Management 6. Key Management
There exist a myriad of ways to establish, communicate, and otherwise There exists a myriad of ways to establish, communicate, and
manage key information in a DTN. Certain DTN deployments might otherwise manage key information in DTN. Certain DTN deployments
follow established protocols for key management whereas other DTN might follow established protocols for key management, whereas other
deployments might require new and novel approaches. BPSec assumes DTN deployments might require new and novel approaches. BPSec
that key management is handled as a separate part of network assumes that key management is handled as a separate part of network
management and this specification neither defines nor requires a management; this specification neither defines nor requires a
specific key management strategy. specific strategy for key management.
7. Security Policy Considerations 7. Security Policy Considerations
When implementing BPSec, several policy decisions must be considered. When implementing BPSec, several policy decisions must be considered.
This section describes key policies that affect the generation, This section describes key policies that affect the generation,
forwarding, and receipt of bundles that are secured using this forwarding, and receipt of bundles that are secured using this
specification. No single set of policy decisions is envisioned to specification. No single set of policy decisions is envisioned to
work for all secure DTN deployments. work for all secure DTN deployments.
o If a bundle is received that contains combinations of security * If a bundle is received that contains combinations of security
operations that are disallowed by this specification the BPA must operations that are disallowed by this specification, the BPA must
determine how to handle the bundle. The bundle may be discarded, determine how to handle the bundle: the bundle may be discarded,
the block affected by the security operation may be discarded, or the block affected by the security operation may be discarded, or
one security operation may be favored over another. one security operation may be favored over another.
o BPAs in the network must understand what security operations they * BPAs in the network must understand what security operations they
should apply to bundles. This decision may be based on the source should apply to bundles. This decision may be based on the source
of the bundle, the destination of the bundle, or some other of the bundle, the destination of the bundle, or some other
information related to the bundle. information related to the bundle.
o If a waypoint has been configured to add a security operation to a * If a waypoint has been configured to add a security operation to a
bundle, and the received bundle already has the security operation bundle, and the received bundle already has the security operation
applied, then the receiver must understand what to do. The applied, then the receiver must understand what to do. The
receiver may discard the bundle, discard the security target and receiver may discard the bundle, discard the security target and
associated BPSec blocks, replace the security operation, or some associated BPSec blocks, replace the security operation, or take
other action. some other action.
o It is RECOMMENDED that security operations be applied to every * It is RECOMMENDED that security operations be applied to every
block in a bundle and that the default behavior of a bundle agent block in a bundle and that the default behavior of a BPA be to use
is to use the security services defined in this specification. the security services defined in this specification. Designers
Designers should only deviate from the use of security operations should only deviate from the use of security operations when the
when the deviation can be justified - such as when doing so causes deviation can be justified -- such as when doing so causes
downstream errors when processing blocks whose contents must be downstream errors when processing blocks whose contents must be
inspected or changed at one or more hops along the path. inspected or changed at one or more hops along the path.
o BCB security contexts can alter the size of extension blocks and * BCB security contexts can alter the size of extension blocks and
the payload block. Security policy SHOULD consider how changes to the payload block. Security policy SHOULD consider how changes to
the size of a block could negatively effect bundle processing the size of a block could negatively effect bundle processing
(e.g., calculating storage needs and scheduling transmission (e.g., calculating storage needs and scheduling transmission
times). times).
o Adding a BIB to a security target that has already been encrypted * Adding a BIB to a security target that has already been encrypted
by a BCB is not allowed. If this condition is likely to be by a BCB is not allowed. If this condition is likely to be
encountered, there are (at least) three possible policies that encountered, there are (at least) three possible policies that
could handle this situation. could handle this situation.
1. At the time of encryption, a security context can be selected 1. At the time of encryption, a security context can be selected
which computes a plain text integrity-protection mechanism that computes a plaintext integrity-protection mechanism that
that is included as a security context result field. is included as a security context result field.
2. The encrypted block may be replicated as a new block with a 2. The encrypted block may be replicated as a new block with a
new block number and given integrity protection. new block number and may be given integrity protection.
3. An encapsulation scheme may be applied to encapsulate the 3. An encapsulation scheme may be applied to encapsulate the
security target (or the entire bundle) such that the security target (or the entire bundle) such that the
encapsulating structure is, itself, no longer the security encapsulating structure is, itself, no longer the security
target of a BCB and may therefore be the security target of a target of a BCB and may therefore be the security target of a
BIB. BIB.
o Security policy SHOULD address whether cipher suites whose cipher * Security policy SHOULD address whether cipher suites whose
text is larger than the initial plain text are permitted and, if ciphertext is larger than the initial plaintext are permitted and,
so, for what types of blocks. Changing the size of a block may if so, for what types of blocks. Changing the size of a block may
cause processing difficulties for networks that calculate block cause processing difficulties for networks that calculate block
offsets into bundles or predict transmission times or storage offsets into bundles or predict transmission times or storage
availability as a function of bundle size. In other cases, availability as a function of bundle size. In other cases,
changing the size of a payload as part of encryption has no changing the size of a payload as part of encryption has no
significant impact. significant impact.
7.1. Security Reason Codes 7.1. Security Reason Codes
Bundle protocol agents (BPAs) must process blocks and bundles in BPAs must process blocks and bundles in accordance with both BP
accordance with both BP policy and BPSec policy. The decision to policy and BPSec policy. The decision to receive, forward, deliver,
receive, forward, deliver, or delete a bundle may be communicated to or delete a bundle may be communicated to the report-to address of
the report-to address of the bundle, in the form of a status report, the bundle in the form of a status report, as a method of tracking
as a method of tracking the progress of the bundle through the the progress of the bundle through the network. The status report
network. The status report for a bundle may be augmented with a for a bundle may be augmented with a "reason code" explaining why the
"reason code" explaining why the particular action was taken on the particular action was taken on the bundle.
bundle.
This section describes a set of reason codes associated with the This section describes a set of reason codes associated with the
security processing of a bundle. The communication of security- security processing of a bundle. The communication of security-
related status reports might reduce the security of a network if related status reports might reduce the security of a network if
these reports are intercepted by unintended recipients. BPSec policy these reports are intercepted by unintended recipients. BPSec policy
SHOULD specify the conditions in which sending security reason codes SHOULD specify the conditions in which sending security reason codes
are appropriate. Examples of appropriate conditions for the use of are appropriate. Examples of appropriate conditions for the use of
security reason codes could include the following. security reason codes could include the following.
o When the report-to address is verified as unchanged from the * When the report-to address is verified as unchanged from the
bundle source. This can occur by placing an appropriate BIB on bundle source. This can occur by placing an appropriate BIB on
the bundle primary block. the bundle primary block.
o When the block containing a status report with a security reason * When the block containing a status report with a security reason
code is encrypted by a BCB. code is encrypted by a BCB.
o When a status report containing a security reason code is only * When a status report containing a security reason code is only
sent for security issues relating to bundles and/or blocks sent for security issues relating to bundles and/or blocks
associated with non-operational user data or otherwise with test associated with non-operational user data or test data.
data.
o When a status report containing a security reason code is only * When a status report containing a security reason code is only
sent for security issues associated with non-operational security sent for security issues associated with non-operational security
contexts, or security contexts using non-operational contexts, or security contexts using non-operational
configurations, such as test keys. configurations, such as test keys.
Security reason codes are assigned in accordance with Section 11.2 Security reason codes are assigned in accordance with Section 11.2
and are as described below. and are as described below.
Missing Security Operation: Missing security operation:
This reason code indicates that a bundle was missing one or This reason code indicates that a bundle was missing one or
more required security operations. This reason code is more required security operations. This reason code is
typically used by a security verifier or security acceptor. typically used by a security verifier or security acceptor.
Unknown Security Operation: Unknown security operation:
This reason code indicates that one or more security operations This reason code indicates that one or more security operations
present in a bundle cannot be understood by the security present in a bundle cannot be understood by the security
verifier or security acceptor for the operation. For example, verifier or security acceptor for the operation. For example,
this reason code may be used if a security block references an this reason code may be used if a security block references an
unknown security context identifier or security context unknown security context identifier or security context
parameter. This reason code should not be used for security parameter. This reason code should not be used for security
operations for which the node is not a security verifier or operations for which the node is not a security verifier or
security acceptor; there is no requirement that all nodes in a security acceptor; there is no requirement that all nodes in a
network understand all security contexts, security context network understand all security contexts, security context
parameters, and security services for every bundle in a parameters, and security services for every bundle in a
network. network.
Unexpected Security Operation: Unexpected security operation:
This reason code indicates that a receiving node is neither a This reason code indicates that a receiving node is neither a
security verifier nor a security acceptor for at least one security verifier nor a security acceptor for at least one
security operation in a bundle. This reason code should not be security operation in a bundle. This reason code should not be
seen as an error condition; not every node is a security seen as an error condition: not every node is a security
verifier or security acceptor for every security operation in verifier or security acceptor for every security operation in
every bundle. In certain networks, this reason code may be every bundle. In certain networks, this reason code may be
useful in identifying misconfigurations of security policy. useful in identifying misconfigurations of security policy.
Failed Security Operation: Failed security operation:
This reason code indicates that one or more security operations This reason code indicates that one or more security operations
in a bundle failed to process as expected for reasons other in a bundle failed to process as expected for reasons other
than misconfiguration. This may occur when a security-source than misconfiguration. This may occur when a security-source
is unable to add a security block to a bundle. This may occur is unable to add a security block to a bundle. This may occur
if the target of a security operation fails to verify using the if the target of a security operation fails to verify using the
defined security context at a security verifier. This may also defined security context at a security verifier. This may also
occur if a security operation fails to be processed without occur if a security operation fails to be processed without
error at a security acceptor. error at a security acceptor.
Conflicting Security Operations: Conflicting security operation:
This reason code indicates that two or more security operations This reason code indicates that two or more security operations
in a bundle are not conformant with the BPSec specification and in a bundle are not conformant with the BPSec specification and
that security processing was unable to proceed because of a that security processing was unable to proceed because of a
BPSec protocol violation. BPSec protocol violation.
8. Security Considerations 8. Security Considerations
Given the nature of DTN applications, it is expected that bundles may Given the nature of DTN applications, it is expected that bundles may
traverse a variety of environments and devices which each pose unique traverse a variety of environments and devices that each pose unique
security risks and requirements on the implementation of security security risks and requirements on the implementation of security
within BPSec. For these reasons, it is important to introduce key within BPSec. For this reason, it is important to introduce key
threat models and describe the roles and responsibilities of the threat models and describe the roles and responsibilities of the
BPSec protocol in protecting the confidentiality and integrity of the BPSec protocol in protecting the confidentiality and integrity of the
data against those threats. This section provides additional data against those threats. This section provides additional
discussion on security threats that BPSec will face and describes how discussion on security threats that BPSec will face and describes how
BPSec security mechanisms operate to mitigate these threats. BPSec security mechanisms operate to mitigate these threats.
The threat model described here is assumed to have a set of The threat model described here is assumed to have a set of
capabilities identical to those described by the Internet Threat capabilities identical to those described by the Internet Threat
Model in [RFC3552], but the BPSec threat model is scoped to Model in [RFC3552], but the BPSec threat model is scoped to
illustrate threats specific to BPSec operating within DTN illustrate threats specific to BPSec operating within DTN
environments and therefore focuses on on-path-attackers (OPAs). In environments; therefore, it focuses on on-path attackers (OPAs). In
doing so, it is assumed that the DTN (or significant portions of the doing so, it is assumed that the delay-tolerant network (or
DTN) are completely under the control of an attacker. significant portions of the delay-tolerant network) are completely
under the control of an attacker.
8.1. Attacker Capabilities and Objectives 8.1. Attacker Capabilities and Objectives
BPSec was designed to protect against OPA threats which may have BPSec was designed to protect against OPA threats that may have
access to a bundle during transit from its source, Alice, to its access to a bundle during transit from its source, Alice, to its
destination, Bob. An OPA node, Olive, is a non-cooperative node destination, Bob. An OPA node, Olive, is a noncooperative node
operating on the DTN between Alice and Bob that has the ability to operating on the delay-tolerant network between Alice and Bob that
receive bundles, examine bundles, modify bundles, forward bundles, has the ability to receive bundles, examine bundles, modify bundles,
and generate bundles at will in order to compromise the forward bundles, and generate bundles at will in order to compromise
confidentiality or integrity of data within the DTN. There are three the confidentiality or integrity of data within the delay-tolerant
classes of OPA nodes which are differentiated based on their access network. There are three classes of OPA nodes that are
to cryptographic material: differentiated based on their access to cryptographic material:
o Unprivileged Node: Olive has not been provisioned within the Unprivileged Node: Olive has not been provisioned within the secure
secure environment and only has access to cryptographic material environment and only has access to cryptographic material that has
which has been publicly-shared. been publicly shared.
o Legitimate Node: Olive is within the secure environment and Legitimate Node: Olive is within the secure environment; therefore,
therefore has access to cryptographic material which has been Olive has access to cryptographic material that has been
provisioned to Olive (i.e., K_M) as well as material which has provisioned to Olive (i.e., K_M) as well as material that has been
been publicly-shared. publicly shared.
o Privileged Node: Olive is a privileged node within the secure Privileged Node: Olive is a privileged node within the secure
environment and therefore has access to cryptographic material environment; therefore, Olive has access to cryptographic material
which has been provisioned to Olive, Alice and/or Bob (i.e. K_M, that has been provisioned to Olive, Alice, and/or Bob (i.e., K_M,
K_A, and/or K_B) as well as material which has been publicly- K_A, and/or K_B) as well as material that has been publicly
shared. shared.
If Olive is operating as a privileged node, this is tantamount to If Olive is operating as a privileged node, this is tantamount to
compromise; BPSec does not provide mechanisms to detect or remove compromise; BPSec does not provide mechanisms to detect or remove
Olive from the DTN or BPSec secure environment. It is up to the Olive from the delay-tolerant network or BPSec secure environment.
BPSec implementer or the underlying cryptographic mechanisms to It is up to the BPSec implementer or the underlying cryptographic
provide appropriate capabilities if they are needed. It should also mechanisms to provide appropriate capabilities if they are needed.
be noted that if the implementation of BPSec uses a single set of It should also be noted that if the implementation of BPSec uses a
shared cryptographic material for all nodes, a legitimate node is single set of shared cryptographic material for all nodes, a
equivalent to a privileged node because K_M == K_A == K_B. For this legitimate node is equivalent to a privileged node because K_M == K_A
reason, sharing cryptographic material in this way is not == K_B. For this reason, sharing cryptographic material in this way
recommended. is not recommended.
A special case of the legitimate node is when Olive is either Alice A special case of the legitimate node is when Olive is either Alice
or Bob (i.e., K_M == K_A or K_M == K_B). In this case, Olive is able or Bob (i.e., K_M == K_A or K_M == K_B). In this case, Olive is able
to impersonate traffic as either Alice or Bob, respectively, which to impersonate traffic as either Alice or Bob, respectively, which
means that traffic to and from that node can be decrypted and means that traffic to and from that node can be decrypted and
encrypted, respectively. Additionally, messages may be signed as encrypted, respectively. Additionally, messages may be signed as
originating from one of the endpoints. originating from one of the endpoints.
8.2. Attacker Behaviors and BPSec Mitigations 8.2. Attacker Behaviors and BPSec Mitigations
skipping to change at page 32, line 8 skipping to change at line 1463
of that bundle and attempt to recover any protected data or of that bundle and attempt to recover any protected data or
cryptographic keying material from the blocks contained within. The cryptographic keying material from the blocks contained within. The
protection mechanism that BPSec provides against this action is the protection mechanism that BPSec provides against this action is the
BCB, which encrypts the contents of its security target, providing BCB, which encrypts the contents of its security target, providing
confidentiality of the data. Of course, it should be assumed that confidentiality of the data. Of course, it should be assumed that
Olive is able to attempt offline recovery of encrypted data, so the Olive is able to attempt offline recovery of encrypted data, so the
cryptographic mechanisms selected to protect the data should provide cryptographic mechanisms selected to protect the data should provide
a suitable level of protection. a suitable level of protection.
When evaluating the risk of eavesdropping attacks, it is important to When evaluating the risk of eavesdropping attacks, it is important to
consider the lifetime of bundles on a DTN. Depending on the network, consider the lifetime of bundles on DTN. Depending on the network,
bundles may persist for days or even years. Long-lived bundles imply bundles may persist for days or even years. Long-lived bundles imply
that the data exists in the network for a longer period of time and, that the data exists in the network for a longer period of time and,
thus, there may be more opportunities to capture those bundles. thus, there may be more opportunities to capture those bundles.
Additionally, bundles that are long-lived imply that the information Additionally, the implication is that long-lived bundles store
stored within them may remain relevant and sensitive for long enough information within that remains relevant and sensitive for long
that, once captured, there is sufficient time to crack encryption enough that, once captured, there is sufficient time to crack
associated with the bundle. If a bundle does persist on the network encryption associated with the bundle. If a bundle does persist on
for years and the cipher suite used for a BCB provides inadequate the network for years and the cipher suite used for a BCB provides
protection, Olive may be able to recover the protected data either inadequate protection, Olive may be able to recover the protected
before that bundle reaches its intended destination or before the data either before that bundle reaches its intended destination or
information in the bundle is no longer considered sensitive. before the information in the bundle is no longer considered
sensitive.
NOTE: Olive is not limited by the bundle lifetime and may retain a NOTE: Olive is not limited by the bundle lifetime and may retain a
given bundle indefinitely. given bundle indefinitely.
NOTE: Irrespective of whether BPSec is used, traffic analysis will be NOTE: Irrespective of whether BPSec is used, traffic analysis will be
possible. possible.
8.2.2. Modification Attacks 8.2.2. Modification Attacks
As a node participating in the DTN between Alice and Bob, Olive will As a node participating in the delay-tolerant network between Alice
also be able to modify the received bundle, including non-BPSec data and Bob, Olive will also be able to modify the received bundle,
such as the primary block, payload blocks, or block processing including non-BPSec data such as the primary block, payload blocks,
control flags as defined in [I-D.ietf-dtn-bpbis]. Olive will be able or block processing control flags as defined in [RFC9171]. Olive
to undertake activities which include modification of data within the will be able to undertake activities including modification of data
blocks, replacement of blocks, addition of blocks, or removal of within the blocks, replacement of blocks, addition of blocks, or
blocks. Within BPSec, both the BIB and BCB provide integrity removal of blocks. Within BPSec, both the BIB and BCB provide
protection mechanisms to detect or prevent data manipulation attempts integrity-protection mechanisms to detect or prevent data
by Olive. manipulation attempts by Olive.
The BIB provides that protection to another block which is its The BIB provides that protection to another block that is its
security target. The cryptographic mechanisms used to generate the security target. The cryptographic mechanisms used to generate the
BIB should be strong against collision attacks and Olive should not BIB should be strong against collision attacks, and Olive should not
have access to the cryptographic material used by the originating have access to the cryptographic material used by the originating
node to generate the BIB (e.g., K_A). If both of these conditions node to generate the BIB (e.g., K_A). If both of these conditions
are true, Olive will be unable to modify the security target or the are true, Olive will be unable to modify the security target or the
BIB and lead Bob to validate the security target as originating from BIB, and thus she cannot lead Bob to validate the security target as
Alice. originating from Alice.
Since BPSec security operations are implemented by placing blocks in Since BPSec security operations are implemented by placing blocks in
a bundle, there is no in-band mechanism for detecting or correcting a bundle, there is no in-band mechanism for detecting or correcting
certain cases where Olive removes blocks from a bundle. If Olive certain cases where Olive removes blocks from a bundle. If Olive
removes a BCB, but keeps the security target, the security target removes a BCB, but keeps the security target, the security target
remains encrypted and there is a possibility that there may no longer remains encrypted and there is a possibility that there may no longer
be sufficient information to decrypt the block at its destination. be sufficient information to decrypt the block at its destination.
If Olive removes both a BCB (or BIB) and its security target there is If Olive removes both a BCB (or BIB) and its security target, there
no evidence left in the bundle of the security operation. Similarly, is no evidence left in the bundle of the security operation.
if Olive removes the BIB but not the security target there is no Similarly, if Olive removes the BIB, but not the security target,
evidence left in the bundle of the security operation. In each of there is no evidence left in the bundle of the security operation.
these cases, the implementation of BPSec must be combined with policy In each of these cases, the implementation of BPSec must be combined
configuration at endpoints in the network which describe the expected with policy configuration at endpoints in the network that describe
and required security operations that must be applied on transmission the expected and required security operations that must be applied on
and are expected to be present on receipt. This or other similar transmission and that are expected to be present on receipt. This or
out-of-band information is required to correct for removal of other similar out-of-band information is required to correct for
security information in the bundle. removal of security information in the bundle.
A limitation of the BIB may exist within the implementation of BIB A limitation of the BIB may exist within the implementation of BIB
validation at the destination node. If Olive is a legitimate node validation at the destination node. If Olive is a legitimate node
within the DTN, the BIB generated by Alice with K_A can be replaced within the delay-tolerant network, the BIB generated by Alice with
with a new BIB generated with K_M and forwarded to Bob. If Bob is K_A can be replaced with a new BIB generated with K_M and forwarded
only validating that the BIB was generated by a legitimate user, Bob to Bob. If Bob is only validating that the BIB was generated by a
will acknowledge the message as originating from Olive instead of legitimate user, Bob will acknowledge the message as originating from
Alice. Validating a BIB indicates only that the BIB was generated by Olive instead of Alice. Validating a BIB indicates only that the BIB
a holder of the relevant key; it does not provide any guarantee that was generated by a holder of the relevant key; it does not provide
the bundle or block was created by the same entity. In order to any guarantee that the bundle or block was created by the same
provide verifiable integrity checks BCB should require an encryption entity. In order to provide verifiable integrity checks, the BCB
scheme that is Indistinguishable under adaptive Chosen Ciphertext should require an encryption scheme that is Indistinguishable under
Attack (IND-CCA2) secure. Such an encryption scheme will guard adaptive Chosen Ciphertext Attack (IND-CCA2) secure. Such an
against signature substitution attempts by Olive. In this case, encryption scheme will guard against signature substitution attempts
Alice creates a BIB with the protected data block as the security by Olive. In this case, Alice creates a BIB with the protected data
target and then creates a BCB with both the BIB and protected data block as the security target and then creates a BCB with both the BIB
block as its security targets. and protected data block as its security targets.
8.2.3. Topology Attacks 8.2.3. Topology Attacks
If Olive is in a OPA position within the DTN, she is able to If Olive is in an OPA position within the delay-tolerant network, she
influence how any bundles that come to her may pass through the is able to influence how any bundles that come to her may pass
network. Upon receiving and processing a bundle that must be routed through the network. Upon receiving and processing a bundle that
elsewhere in the network, Olive has three options as to how to must be routed elsewhere in the network, Olive has three options as
proceed: not forward the bundle, forward the bundle as intended, or to how to proceed: not forward the bundle, forward the bundle as
forward the bundle to one or more specific nodes within the network. intended, or forward the bundle to one or more specific nodes within
the network.
Attacks that involve re-routing the packets throughout the network Attacks that involve rerouting the bundles throughout the network are
are essentially a special case of the modification attacks described essentially a special case of the modification attacks described in
in this section where the attacker is modifying fields within the this section, one where the attacker is modifying fields within the
primary block of the bundle. Given that BPSec cannot encrypt the primary block of the bundle. Given that BPSec cannot encrypt the
contents of the primary block, alternate methods must be used to contents of the primary block, alternate methods must be used to
prevent this situation. These methods may include requiring BIBs for prevent this situation. These methods may include requiring BIBs for
primary blocks, using encapsulation, or otherwise strategically primary blocks, using encapsulation, or otherwise strategically
manipulating primary block data. The specifics of any such manipulating primary block data. The details of any such mitigation
mitigation technique are specific to the implementation of the technique are specific to the implementation of the deploying network
deploying network and outside of the scope of this document. and are outside of the scope of this document.
Furthermore, routing rules and policies may be useful in enforcing Furthermore, routing rules and policies may be useful in enforcing
particular traffic flows to prevent topology attacks. While these particular traffic flows to prevent topology attacks. While these
rules and policies may utilize some features provided by BPSec, their rules and policies may utilize some features provided by BPSec, their
definition is beyond the scope of this specification. definition is beyond the scope of this specification.
8.2.4. Message Injection 8.2.4. Message Injection
Olive is also able to generate new bundles and transmit them into the Olive is also able to generate new bundles and transmit them into the
DTN at will. These bundles may either be copies or slight delay-tolerant network at will. These bundles may be either 1)
modifications of previously-observed bundles (i.e., a replay attack) copies or slight modifications of previously observed bundles (i.e.,
or entirely new bundles generated based on the Bundle Protocol, a replay attack) or 2) entirely new bundles generated based on the
BPSec, or other bundle-related protocols. With these attacks Olive's Bundle Protocol, BPSec, or other bundle-related protocols. With
objectives may vary, but may be targeting either the bundle protocol these attacks, Olive's objectives may vary, but may be targeting
or application-layer protocols conveyed by the bundle protocol. The either the Bundle Protocol or application-layer protocols conveyed by
target could also be the storage and compute of the nodes running the the Bundle Protocol. The target could also be the storage and
bundle or application layer protocols (e.g., a denial of service to computing capabilities of the nodes running the bundle or
flood on the storage of the store-and-forward mechanism; or compute application-layer protocols (e.g., a denial of service to flood on
which would process the packets and perhaps prevent other the storage of the store-and-forward mechanism or a computation that
activities). would process the bundles and perhaps prevent other activities).
BPSec relies on cipher suite capabilities to prevent replay or forged BPSec relies on cipher suite capabilities to prevent replay or forged
message attacks. A BCB used with appropriate cryptographic message attacks. A BCB used with appropriate cryptographic
mechanisms may provide replay protection under certain circumstances. mechanisms may provide replay protection under certain circumstances.
Alternatively, application data itself may be augmented to include Alternatively, application data itself may be augmented to include
mechanisms to assert data uniqueness and then protected with a BIB, a mechanisms to assert data uniqueness and then be protected with a
BCB, or both along with other block data. In such a case, the BIB, a BCB, or both along with other block data. In such a case, the
receiving node would be able to validate the uniqueness of the data. receiving node would be able to validate the uniqueness of the data.
For example, a BIB may be used to validate the integrity of a For example, a BIB may be used to validate the integrity of a
bundle's primary block, which includes a timestamp and lifetime for bundle's primary block, which includes a timestamp and lifetime for
the bundle. If a bundle is replayed outside of its lifetime, then the bundle. If a bundle is replayed outside of its lifetime, then
the replay attack will fail as the bundle will be discarded. the replay attack will fail as the bundle will be discarded.
Similarly, additional blocks such as the Bundle Age may be signed and Similarly, additional blocks, such as the Bundle Age, may be signed
validated to identify replay attacks. Finally, security context and validated to identify replay attacks. Finally, security context
parameters within BIB and BCB blocks may include anti-replay parameters within BIBs and BCBs may include anti-replay mechanisms
mechanisms such as session identifiers, nonces, and dynamic passwords such as session identifiers, nonces, and dynamic passwords as
as supported by network characteristics. supported by network characteristics.
9. Security Context Considerations 9. Security Context Considerations
9.1. Mandating Security Contexts 9.1. Mandating Security Contexts
Because of the diversity of networking scenarios and node Because of the diversity of networking scenarios and node
capabilities that may utilize BPSec there is a risk that a single capabilities that may utilize BPSec, there is a risk that a single
security context mandated for every possible BPSec implementation is security context mandated for every possible BPSec implementation is
not feasible. For example, a security context appropriate for a not feasible. For example, a security context appropriate for a
resource-constrained node with limited connectivity may be resource-constrained node with limited connectivity may be
inappropriate for use in a well-resourced, well connected node. inappropriate for use in a well-resourced, well-connected node.
This does not mean that the use of BPSec in a particular network is This does not mean that the use of BPSec in a particular network is
meant to be used without security contexts for interoperability and meant to happen without security contexts for interoperability and
default behavior. Network designers must identify the minimal set of default behavior. Network designers must identify the minimal set of
security contexts necessary for functions in their network. For security contexts necessary for functions in their network. For
example, a default set of security contexts could be created for use example, a default set of security contexts could be created for use
over the terrestrial Internet and required by any BPSec over the terrestrial Internet, and they could be required by any
implementation communicating over the terrestrial Internet. BPSec implementation communicating over the terrestrial Internet.
To ensure interoperability among various implementations, all BPSec To ensure interoperability among various implementations, all BPSec
implementations MUST support at least the current IETF standards- implementations MUST support at least the current, mandatory security
track mandatory security context(s). As of this writing, that BCP context(s) defined in IETF Standards Track RFCs. As of this writing,
mandatory security context is specified in that BP mandatory security context is specified in [RFC9173], but the
[I-D.ietf-dtn-bpsec-default-sc], but the mandatory security mandatory security context(s) might change over time in accordance
context(s) might change over time in accordance with usual IETF with usual IETF processes. Such changes are likely to occur in the
processes. Such changes are likely to occur in the future if/when future if/when flaws are discovered in the applicable cryptographic
flaws are discovered in the applicable cryptographic algorithms, for algorithms, for example.
example.
Additionally, BPsec implementations need to support the security Additionally, BPSec implementations need to support the security
contexts which are specified and/or used by the BP networks in which contexts that are required by the BP networks in which they are
they are deployed. deployed.
If a node serves as a gateway amongst two or more networks, the BPSec If a node serves as a gateway between two or more networks, the BPSec
implementation at that node needs to support the union of security implementation at that node needs to support the union of security
contexts mandated in those networks. contexts mandated in those networks.
BPSec has been designed to allow for a diversity of security contexts BPSec has been designed to allow for a diversity of security contexts
and for new contexts to be defined over time. The use of different and for new contexts to be defined over time. The use of different
security contexts does not change the BPSec protocol itself and the security contexts does not change the BPSec protocol itself, and the
definition of new security contexts MUST adhere to the requirements definition of new security contexts MUST adhere to the requirements
of such contexts as presented in this section and generally in this of such contexts as presented in this section and generally in this
specification. specification.
Implementors should monitor the state of security context Implementers should monitor the state of security context
specifications to check for future updates and replacement. specifications to check for future updates and replacement.
9.2. Identification and Configuration 9.2. Identification and Configuration
Security blocks uniquely identify the security context to be used in Security blocks uniquely identify the security context to be used in
the processing of their security services. The security context for the processing of their security services. The security context for
a security block MUST be uniquely identifiable and MAY use parameters a security block MUST be uniquely identifiable and MAY use parameters
for customization. for customization.
To reduce the number of security contexts used in a network, security To reduce the number of security contexts used in a network, security
skipping to change at page 36, line 31 skipping to change at line 1676
produced for each security service. produced for each security service.
Network operators must determine the number, type, and configuration Network operators must determine the number, type, and configuration
of security contexts in a system. Networks with rapidly changing of security contexts in a system. Networks with rapidly changing
configurations may define relatively few security contexts with each configurations may define relatively few security contexts with each
context customized with multiple parameters. For networks with more context customized with multiple parameters. For networks with more
stability, or an increased need for confidentiality, a larger number stability, or an increased need for confidentiality, a larger number
of contexts can be defined with each context supporting few, if any, of contexts can be defined with each context supporting few, if any,
parameters. parameters.
Security Context Examples +=============+============+=======================================+
| Context | Parameters | Definition |
+------------+------------+-----------------------------------------+ | Type | | |
| Context | Parameters | Definition | +=============+============+=======================================+
| Type | | | | Key | Encrypted | AES-GCM-256 cipher suite with |
+------------+------------+-----------------------------------------+ | Exchange | Key, IV | provided ephemeral key encrypted with |
| Key | Encrypted | AES-GCM-256 cipher suite with provided | | AES | | a predetermined key encryption key |
| Exchange | Key, IV | ephemeral key encrypted with a | | | | and cleartext initialization vector. |
| AES | | predetermined key encryption key and | +-------------+------------+---------------------------------------+
| | | clear text initialization vector. | | Pre-Shared | IV | AES-GCM-256 cipher suite with |
| Pre-shared | IV | AES-GCM-256 cipher suite with | | Key AES | | predetermined key and predetermined |
| Key AES | | predetermined key and predetermined | | | | key-rotation policy. |
| | | key rotation policy. | +-------------+------------+---------------------------------------+
| Out of | None | AES-GCM-256 cipher suite with all info | | Out-of-Band | None | AES-GCM-256 cipher suite with all |
| Band AES | | predetermined. | | AES | | info predetermined. |
+------------+------------+-----------------------------------------+ +-------------+------------+---------------------------------------+
Table 1 Table 1: Security Context Examples
9.3. Authorship 9.3. Authorship
Developers or implementers should consider the diverse performance Developers or implementers should consider the diverse performance
and conditions of networks on which the Bundle Protocol (and and conditions of networks on which the Bundle Protocol (and,
therefore BPSec) will operate. Specifically, the delay and capacity therefore, BPSec) will operate. Specifically, the delay and capacity
of delay-tolerant networks can vary substantially. Developers should of DTNs can vary substantially. Developers should consider these
consider these conditions to better describe the conditions when conditions to better describe the conditions in which those contexts
those contexts will operate or exhibit vulnerability, and selection will operate or exhibit vulnerability, and selection of these
of these contexts for implementation should be made with contexts for implementation should be made with consideration for
consideration for this reality. There are key differences that may this reality. There are key differences that may limit the
limit the opportunity for a security context to leverage existing opportunity for a security context to leverage existing cipher suites
cipher suites and technologies that have been developed for use in and technologies that have been developed for use in more reliable
traditional, more reliable networks: networks:
o Data Lifetime: Depending on the application environment, bundles Data Lifetime: Depending on the application environment, bundles may
may persist on the network for extended periods of time, perhaps persist on the network for extended periods of time, perhaps even
even years. Cryptographic algorithms should be selected to ensure years. Cryptographic algorithms should be selected to ensure
protection of data against attacks for a length of time reasonable protection of data against attacks for a length of time reasonable
for the application. for the application.
o One-Way Traffic: Depending on the application environment, it is One-Way Traffic: Depending on the application environment, it is
possible that only a one-way connection may exist between two possible that only a one-way connection may exist between two
endpoints, or if a two-way connection does exist, the round- trip endpoints, or if a two-way connection does exist, the round-trip
time may be extremely large. This may limit the utility of time may be extremely large. This may limit the utility of
session key generation mechanisms, such as Diffie-Hellman, as a session key generation mechanisms, such as Diffie-Hellman, as a
two-way handshake may not be feasible or reliable. two-way handshake may not be feasible or reliable.
o Opportunistic Access: Depending on the application environment, a Opportunistic Access: Depending on the application environment, a
given endpoint may not be guaranteed to be accessible within a given endpoint may not be guaranteed to be accessible within a
certain amount of time. This may make asymmetric cryptographic certain amount of time. This may make asymmetric cryptographic
architectures which rely on a key distribution center or other architectures that rely on a key distribution center or other
trust center impractical under certain conditions. trust center impractical under certain conditions.
When developing security contexts for use with BPSec, the following When developing security contexts for use with BPSec, the following
information SHOULD be considered for inclusion in these information SHOULD be considered for inclusion in these
specifications. specifications.
o Security Context Parameters. Security contexts MUST define their Security Context Parameters: Security contexts MUST define their
parameter Ids, the data types of those parameters, and their CBOR parameter Ids, the data types of those parameters, and their CBOR
encoding. encoding.
o Security Results. Security contexts MUST define their security Security Results: Security contexts MUST define their security
result Ids, the data types of those results, and their CBOR result Ids, the data types of those results, and their CBOR
encoding. encoding.
o New Canonicalizations. Security contexts may define new New Canonicalizations: Security contexts may define new
canonicalization algorithms as necessary. canonicalization algorithms as necessary.
o Cipher-Text Size. Security contexts MUST state whether their Ciphertext Size: Security contexts MUST state whether their
associated cipher suites generate cipher text (to include any associated cipher suites generate ciphertext (to include any
authentication information) that is of a different size than the authentication information) that is of a different size than the
input plain text. input plaintext.
If a security context does not wish to alter the size of the plain If a security context does not wish to alter the size of the
text it should place overflow bytes and authentication tags in plaintext, it should place overflow bytes and authentication tags
security result fields. in security result fields.
o Block Header Information. Security contexts SHOULD include block Block Header Information: Security contexts SHOULD include block
header information that is considered to be immutable for the header information that is considered to be immutable for the
block. This information MAY include the block type code, block block. This information MAY include the block type code, block
number, CRC Type and CRC field (if present or if missing and number, CRC type, and CRC field (if present or if missing and
unlikely to be added later), and possibly certain block processing unlikely to be added later), and possibly certain block processing
control flags. Designers should input these fields as additional control flags. Designers should input these fields as additional
data for integrity protection when these fields are expected to data for integrity protection when these fields are expected to
remain unchanged over the path the block will take from the remain unchanged over the path the block will take from the
security source to the security acceptor. Security contexts security source to the security acceptor. Security contexts
considering block header information MUST describe expected considering block header information MUST describe expected
behavior when these fields fail their integrity verification. behavior when these fields fail their integrity verification.
o Handling CRC Fields. Security contexts may include algorithms Handling CRC Fields: Security contexts may include algorithms that
that alter the contexts of their security target block, such as alter the contexts of their security target block, such as the
the case when encrypting the block-type-specific data of a target case when encrypting the block-type-specific data of a target
block as part oF a BCB confidentiality service. Security context block as part of a BCB confidentiality service. Security context
specifications SHOULD address how preexisting CRC-Type and CRC- specifications SHOULD address how preexisting CRC type and CRC
Value fields be handled. For example, a BCB security context value fields be handled. For example, a BCB security context
could remove the plain-text CRC value from its target upon could remove the plaintext CRC value from its target upon
encryption and replace or recalculate the value upon decryption. encryption and replace or recalculate the value upon decryption.
10. Defining Other Security Blocks 10. Defining Other Security Blocks
Other security blocks (OSBs) may be defined and used in addition to Other Security Blocks (OSBs) may be defined and used in addition to
the security blocks identified in this specification. Both the usage the security blocks identified in this specification. BIB, BCB, and
of BIB, BCB, and any future OSBs can co-exist within a bundle and can any future OSBs can coexist within a bundle and can be considered in
be considered in conformance with BPSec if each of the following conformance with BPSec if all of the following requirements are met
requirements are met by any future identified security blocks. by any future identified security blocks.
o Other security blocks (OSBs) MUST NOT reuse any enumerations * OSBs MUST NOT reuse any enumerations identified in this
identified in this specification, to include the block type codes specification, to include the block type codes for BIB and BCB.
for BIB and BCB.
o An OSB definition MUST state whether it can be the target of a BIB * An OSB definition MUST state whether it can be the target of a BIB
or a BCB. The definition MUST also state whether the OSB can or a BCB. The definition MUST also state whether the OSB can
target a BIB or a BCB. target a BIB or a BCB.
o An OSB definition MUST provide a deterministic processing order in * An OSB definition MUST provide a deterministic processing order in
the event that a bundle is received containing BIBs, BCBs, and the event that a bundle is received containing BIBs, BCBs, and
OSBs. This processing order MUST NOT alter the BIB and BCB OSBs. This processing order MUST NOT alter the BIB and BCB
processing orders identified in this specification. processing orders identified in this specification.
o An OSB definition MUST provide a canonicalization algorithm if the * An OSB definition MUST provide a canonicalization algorithm if the
default non-primary-block canonicalization algorithm cannot be default algorithm for non-primary-block canonicalization cannot be
used to generate a deterministic input for a cipher suite. This used to generate a deterministic input for a cipher suite. This
requirement can be waived if the OSB is defined so as to never be requirement can be waived if the OSB is defined so as to never be
the security target of a BIB or a BCB. the security target of a BIB or a BCB.
o An OSB definition MUST NOT require any behavior of a BPSEC-BPA * An OSB definition MUST NOT require any behavior of a BPSec BPA
that is in conflict with the behavior identified in this that is in conflict with the behavior identified in this
specification. In particular, the security processing specification. In particular, the security processing
requirements imposed by this specification must be consistent requirements imposed by this specification must be consistent
across all BPSEC-BPAs in a network. across all BPSec BPAs in a network.
o The behavior of an OSB when dealing with fragmentation must be * The behavior of an OSB when dealing with fragmentation must be
specified and MUST NOT lead to ambiguous processing states. In specified and MUST NOT lead to ambiguous processing states. In
particular, an OSB definition should address how to receive and particular, an OSB definition should address how to receive and
process an OSB in a bundle fragment that may or may not also process an OSB in a bundle fragment that may or may not also
contain its security target. An OSB definition should also contain its security target. An OSB definition should also
address whether an OSB may be added to a bundle marked as a address whether an OSB may be added to a bundle marked as a
fragment. fragment.
Additionally, policy considerations for the management, monitoring, Additionally, policy considerations for the management, monitoring,
and configuration associated with blocks SHOULD be included in any and configuration associated with blocks SHOULD be included in any
OSB definition. OSB definition.
NOTE: The burden of showing compliance with processing rules is NOTE: The burden of showing compliance with processing rules is
placed upon the specifications defining new security blocks and the placed upon the specifications defining new security blocks, and the
identification of such blocks shall not, alone, require maintenance identification of such blocks shall not, alone, require maintenance
of this specification. of this specification.
11. IANA Considerations 11. IANA Considerations
This specification includes fields requiring registries managed by This specification includes fields that require registries managed by
IANA. IANA.
11.1. Bundle Block Types 11.1. Bundle Block Types
This specification allocates two block types from the existing This specification allocates two block types from the existing
"Bundle Block Types" registry defined in [RFC6255]. "Bundle Block Types" registry defined in [RFC6255].
Additional Entries for the Bundle Block-Type Codes Registry: +=======+=======================+===============+
| Value | Description | Reference |
+-------+-----------------------------+---------------+ +=======+=======================+===============+
| Value | Description | Reference | | 11 | Block Integrity | This document |
+-------+-----------------------------+---------------+ +-------+-----------------------+---------------+
| TBA | Block Integrity Block | This document | | 12 | Block Confidentiality | This document |
| TBA | Block Confidentiality Block | This document | +-------+-----------------------+---------------+
+-------+-----------------------------+---------------+
Table 2 Table 2: Additional Entries for the "Bundle
Block Types" Registry
The Bundle Block Types namespace notes whether a block type is meant The "Bundle Block Types" registry notes whether a block type is meant
for use in BP version 6, BP version 7, or both. The two block types for use in BP version 6, BP version 7 (BPv7), or both. The two block
defined in this specification are meant for use with BP version 7. types defined in this specification are meant for use with BPv7.
11.2. Bundle Status Report Reason Codes 11.2. Bundle Status Report Reason Codes
This specification allocates five reason codes from the existing This specification allocates five reason codes from the existing
"Bundle Status Report Reason Codes" registry defined in [RFC6255]. "Bundle Status Report Reason Codes" registry defined in [RFC6255].
Additional Entries for the Bundle Status Report Reason Codes +============+=======+============================+================+
Registry: | BP Version | Value | Description | Reference |
+============+=======+============================+================+
| 7 | 12 | Missing security operation | This document, |
| | | | Section 7.1 |
+------------+-------+----------------------------+----------------+
| 7 | 13 | Unknown security operation | This document, |
| | | | Section 7.1 |
+------------+-------+----------------------------+----------------+
| 7 | 14 | Unexpected security | This document, |
| | | operation | Section 7.1 |
+------------+-------+----------------------------+----------------+
| 7 | 15 | Failed security operation | This document, |
| | | | Section 7.1 |
+------------+-------+----------------------------+----------------+
| 7 | 16 | Conflicting security | This document, |
| | | operation | Section 7.1 |
+------------+-------+----------------------------+----------------+
+---------+-------+-----------------------+-------------------------+ Table 3: Additional Entries for the "Bundle Status Report Reason
| BP | Value | Description | Reference | Codes" Registry
| Version | | | |
+---------+-------+-----------------------+-------------------------+
| 7 | TBD | Missing Security | This document, Section |
| | | Operation | Section 7.1 |
| 7 | TBD | Unknown Security | This document, Section |
| | | Operation | Section 7.1 |
| 7 | TBD | Unexpected Security | This document, Section |
| | | Operation | Section 7.1 |
| 7 | TBD | Failed Security | This document, Section |
| | | Operation | Section 7.1 |
| 7 | TBD | Conflicting Security | This document, Section |
| | | Operation | Section 7.1 |
+---------+-------+-----------------------+-------------------------+
11.3. Security Context Identifiers 11.3. Security Context Identifiers
BPSec has a Security Context Identifier field for which IANA is BPSec has a Security Context Identifier field for which IANA has
requested to create and maintain a new registry named "BPSec Security created a new registry named "BPSec Security Context Identifiers".
Context Identifiers". Initial values for this registry are given Initial values for this registry are given below.
below.
The registration policy for this registry is: Specification Required.
The value range is: signed 16-bit integer. The registration policy for this registry is Specification Required
(see [RFC8126]).
BPSec Security Context Identifier Registry The value range: signed 16-bit integer.
+-------+-------------+---------------+ +=======+=============+===============+
| Value | Description | Reference | | Value | Description | Reference |
+-------+-------------+---------------+ +=======+=============+===============+
| < 0 | Reserved | This document | | < 0 | Reserved | This document |
+-------+-------------+---------------+
| 0 | Reserved | This document | | 0 | Reserved | This document |
+-------+-------------+---------------+ +-------+-------------+---------------+
Table 3 Table 4: "BPSec Security Context
Identifier" Registry
Negative security context identifiers are reserved for local/site- Negative security context identifiers are reserved for local/site-
specific uses. The use of 0 as a security context identifier is for specific uses. The use of 0 as a security context identifier is for
non-operational testing purposes only. nonoperational testing purposes only.
12. References 12. References
12.1. Normative References 12.1. Normative References
[I-D.ietf-dtn-bpbis]
Burleigh, S., Fall, K., and E. Birrane, "Bundle Protocol
Version 7", draft-ietf-dtn-bpbis-31 (work in progress),
January 2021.
[I-D.ietf-dtn-bpsec-default-sc]
Birrane, E., "BPSec Default Security Contexts", draft-
ietf-dtn-bpsec-default-sc-01 (work in progress), February
2021.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC [RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552, Text on Security Considerations", BCP 72, RFC 3552,
DOI 10.17487/RFC3552, July 2003, DOI 10.17487/RFC3552, July 2003,
<https://www.rfc-editor.org/info/rfc3552>. <https://www.rfc-editor.org/info/rfc3552>.
skipping to change at page 42, line 10 skipping to change at line 1927
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object [RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", STD 94, RFC 8949, Representation (CBOR)", STD 94, RFC 8949,
DOI 10.17487/RFC8949, December 2020, DOI 10.17487/RFC8949, December 2020,
<https://www.rfc-editor.org/info/rfc8949>. <https://www.rfc-editor.org/info/rfc8949>.
12.2. Informative References [RFC9171] Burleigh, S., Fall, K., and E. Birrane, III, "Bundle
Protocol Version 7", RFC 9171, DOI 10.17487/RFC9171,
January 2022, <https://www.rfc-editor.org/info/rfc9171>.
[I-D.birrane-dtn-sbsp] [RFC9173] Birrane, III, E., White, A., and S. Heiner, "Default
Birrane, E., Pierce-Mayer, J., and D. Iannicca, Security Contexts for Bundle Protocol Security (BPSec)",
"Streamlined Bundle Security Protocol Specification", RFC 9173, DOI 10.17487/RFC9173, January 2022,
draft-birrane-dtn-sbsp-01 (work in progress), October <https://www.rfc-editor.org/info/rfc9173>.
2015.
12.2. Informative References
[RFC4838] Cerf, V., Burleigh, S., Hooke, A., Torgerson, L., Durst, [RFC4838] Cerf, V., Burleigh, S., Hooke, A., Torgerson, L., Durst,
R., Scott, K., Fall, K., and H. Weiss, "Delay-Tolerant R., Scott, K., Fall, K., and H. Weiss, "Delay-Tolerant
Networking Architecture", RFC 4838, DOI 10.17487/RFC4838, Networking Architecture", RFC 4838, DOI 10.17487/RFC4838,
April 2007, <https://www.rfc-editor.org/info/rfc4838>. April 2007, <https://www.rfc-editor.org/info/rfc4838>.
[RFC6257] Symington, S., Farrell, S., Weiss, H., and P. Lovell, [RFC6257] Symington, S., Farrell, S., Weiss, H., and P. Lovell,
"Bundle Security Protocol Specification", RFC 6257, "Bundle Security Protocol Specification", RFC 6257,
DOI 10.17487/RFC6257, May 2011, DOI 10.17487/RFC6257, May 2011,
<https://www.rfc-editor.org/info/rfc6257>. <https://www.rfc-editor.org/info/rfc6257>.
Appendix A. Acknowledgements [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
Acknowledgments
The following participants contributed technical material, use cases, The following participants contributed technical material, use cases,
and useful thoughts on the overall approach to this security and useful thoughts on the overall approach to this security
specification: Scott Burleigh of the Jet Propulsion Laboratory, specification: Scott Burleigh of the IPNGROUP, Angela Hennessy of the
Angela Hennessy of the Laboratory for Telecommunications Sciences, Laboratory for Telecommunications Sciences, Amy Alford and Cherita
and Amy Alford, Angela Dalton, and Cherita Corbett of the Johns Corbett of the Johns Hopkins University Applied Physics Laboratory
Hopkins University Applied Physics Laboratory. (JHU/APL), and Angela Dalton of AMD Research.
Additionally, Benjamin Kaduk of Akamai Technologies provided a
detailed technical review that resulted in a stronger and more
precise specification.
Authors' Addresses Authors' Addresses
Edward J. Birrane, III Edward J. Birrane, III
The Johns Hopkins University Applied The Johns Hopkins University Applied Physics Laboratory
Physics Laboratory
11100 Johns Hopkins Rd. 11100 Johns Hopkins Rd.
Laurel, MD 20723 Laurel, MD 20723
US United States of America
Phone: +1 443 778 7423 Phone: +1 443 778 7423
Email: Edward.Birrane@jhuapl.edu Email: Edward.Birrane@jhuapl.edu
Kenneth McKeever Kenneth McKeever
The Johns Hopkins University Applied The Johns Hopkins University Applied Physics Laboratory
Physics Laboratory
11100 Johns Hopkins Rd. 11100 Johns Hopkins Rd.
Laurel, MD 20723 Laurel, MD 20723
US United States of America
Phone: +1 443 778 2237 Phone: +1 443 778 2237
Email: Ken.McKeever@jhuapl.edu Email: Ken.McKeever@jhuapl.edu
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