Network Working Group M. Miller Internet-Draft P. Saint-Andre Intended status: Standards Track Cisco Systems, Inc. Expires: March 10, 2014 September 06, 2013 PKIX over Secure HTTP (POSH) draft-miller-posh-01 Abstract Experience has shown that it is extremely difficult to deploy proper PKIX certificates for TLS in multi-tenanted environments, since certification authorities will not issue certificates for hosted domains to hosting services, hosted domains do not want hosting services to hold their private keys, and hosting services wish to avoid liability for holding those keys. As a result, domains hosted in multi-tenanted environments often deploy non-HTTP applications such as email and instant messaging using certificates that identify the hosting service, not the hosted domain. Such deployments force end users and peer services to accept a certificate with an improper identifier, resulting in obvious security implications. This document defines two methods that make it easier to deploy certificates for proper server identity checking in non-HTTP application protocols. The first method enables the TLS client associated with a user agent or peer application server to obtain the end-entity certificate of a hosted domain over secure HTTP as an alternative to standard PKIX techniques. The second method enables a hosted domain to securely delegate a non-HTTP application to a hosting service using redirects provided by HTTPS itself or by a pointer in a file served over HTTPS at the hosted domain. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on March 10, 2014. Miller & Saint-Andre Expires March 10, 2014 [Page 1] Internet-Draft POSH September 2013 Copyright Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Discussion Venue . . . . . . . . . . . . . . . . . . . . . . 4 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Obtaining Verification Materials . . . . . . . . . . . . . . 4 4.1. Source Domain Possesses PKIX Certificate . . . . . . . . 5 4.2. Source Domain References PKIX Certificate . . . . . . . . 7 4.3. Performing Verification . . . . . . . . . . . . . . . . . 8 5. Secure Delegation . . . . . . . . . . . . . . . . . . . . . . 9 6. Order of Operations . . . . . . . . . . . . . . . . . . . . . 9 7. Caching Results . . . . . . . . . . . . . . . . . . . . . . . 9 8. Alternates and Roll-over . . . . . . . . . . . . . . . . . . 9 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 10. Security Considerations . . . . . . . . . . . . . . . . . . . 13 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 11.1. Normative References . . . . . . . . . . . . . . . . . . 13 11.2. Informative References . . . . . . . . . . . . . . . . . 14 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 1. Introduction We start with a thought experiment. Imagine that you work on the operations team of a hosting company that provides the "foo" service (or email or instant messaging or social networking service) for ten thousand different customer organizations. Each customer wants their service to be identified by the customer's domain name (e.g., foo.example.com), not the hosting company's domain name (e.g., hosting.example.net). Miller & Saint-Andre Expires March 10, 2014 [Page 2] Internet-Draft POSH September 2013 In order to properly secure each customer's "foo" service via Transport Layer Security (TLS) [RFC5246], you need to obtain PKIX certificates [RFC5280] containing identifiers such as foo.example.com, as explained in the "CertID" specification [RFC6125]. Unfortunately, you can't obtain such certificates because: o Certification authorities won't issue such certificates to you because you work for the hosting company, not the customer organization. o Customers won't obtain such certificates and then give them (plus the associated private keys) to you because their legal department is worried about liability. o You don't want to install such certificates (plus the associated private keys) on your servers anyway because your legal department is worried about liability, too. Given your inability to deploy public keys / certificates containing the right identifiers, your back-up approach was always to use a certificate containing hosting.example.net as the identifier. However, more and more customers and end users are complaining about warning messages in user agents and the inherent security issues involved with taking a "leap of faith" to accept the identity mismatch between the source domain (foo.example.com) and the delegated domain (hosting.example.net). This situation is both insecure and unsustainable. You have investigated the possibility of using DNS Security [RFC4033] and DNS- Based Authentication of Named Entities (DANE) [RFC6698] to solve the problem. However, your customers and your operations team have told you that they will not be able to deploy DNSSEC and DANE for several years at least. The product managers in your company are pushing you to find a method that can be deployed more quickly to overcome the lack of proper server identity checking for your hosted customers. One possible approach is to ask each customer to provide the public key / certificate for the "foo" service at a special HTTPS URI on their website ("https://foo.example.com/.well-known/posh.foo.json" is one possibility). This could be a public key that you generate for the customer, but because the customer hosts it via HTTPS, any user agent can find that public key and check it against the public key you provide during TLS negotiation for the "foo" service (as one added benefit, the customer never needs to hand you a private key). Alternatively, the customer can redirect requests for that special Miller & Saint-Andre Expires March 10, 2014 [Page 3] Internet-Draft POSH September 2013 HTTPS URI to an HTTPS URI at your own website, thus making it explicit that they have delegated the "foo" service to you. The approach sketched out above, called POSH ("PKIX Over Secure HTTP"), is explained in the remainder of this document. 2. Discussion Venue The discussion venue for this document is the posh@ietf.org mailing list; visit https://www.ietf.org/mailman/listinfo/posh for subscription information and discussion archives. 3. Terminology This document inherits security terminology from [RFC5280]. The terms "source domain", "derived domain", "reference identifier", and "presented identifier" are used as defined in the "CertID" specification [RFC6125]. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 4. Obtaining Verification Materials Server identity checking (see [RFC6125]) involves three different aspects: 1. A proof of the TLS server's identity (in PKIX, this takes the form of a PKIX certificate [RFC5280]). 2. Rules for checking the certificate (which vary by application protocol, although [RFC6125] attempts to harmonize those rules). 3. The materials that a TLS client uses to verify the TLS server's identity or check the TLS server's proof (in PKIX, this takes the form of chaining the end-entity certificate back to a trusted root and performing all validity checks as described in [RFC5280], [RFC6125], and the relevant application protocol specification). When POSH is used, the first two aspects remain the same: the TLS server proves it identity by presenting a PKIX certificate [RFC5280] and the certificate is checked according to the rules defined in the appropriate application protocol specification (such as [RFC6120] for Miller & Saint-Andre Expires March 10, 2014 [Page 4] Internet-Draft POSH September 2013 XMPP). However, the TLS client obtains the materials it will use to verify the server's proof by retrieving a JSON Web Key (JWK) set [JOSE-JWK] over HTTPS ([RFC2616] and [RFC2818]) from a well-known URI [RFC5785]. The process for retrieving a PKIX certificate over secure HTTP is as follows. 1. The TLS client performs an HTTPS GET at the source domain to the path "/.well-known/posh.{servicedesc}.json". The value of "{servicedesc}" is application-specific; see Section 9 of this document for more details. For example, if the application protocol is some hypothetical "Foo" service, then "{servicedesc}" could be "foo"; thus if a Foo client were to use POSH to verify a Foo server for the domain "foo.example.com", the HTTPS GET request would be as follows: GET /.well-known/posh.foo.json HTTP/1.1 Host: foo.example.com 2. The source domain HTTPS server responds in one of three ways: * If it possesses a PKIX certificate for the requested path, it responds as detailed in Section 4.1. * If it has a reference to where the PKIX certificate can be obtained, it responds as detailed in Section 4.2. * If it does not have any PKIX certificate for the requested path, it responds with a client error status code (e.g., 404). 4.1. Source Domain Possesses PKIX Certificate If the source domain HTTPS server possesses the certificate information, it responds to the HTTPS GET with a success status code and the message body set to a JSON Web Key (JWK) set [JOSE-JWK]. The JWK set MUST contain at least one JWK object. Each included JWK object MUST possess the following information: Miller & Saint-Andre Expires March 10, 2014 [Page 5] Internet-Draft POSH September 2013 o The "kty" field set to the appropriate key type used for TLS connections (e.g., "RSA" for a certificate using an RSA key). o The required parameters for the key type (e.g., "n" and "e" for a certificate using an RSA key). Additionally, each JWK object MUST possess at least one of the following: o The "x5t" field set to the certificate thumbprint, as per section 3.6 of [JOSE-JWK]. o The "x5c" field set to the certificate chain, as per section 3.7 of [JOSE-JWK]. The following example illustrates the usage described above. Example Content Response HTTP/1.1 200 OK Content-Type: application/jwk-set+json Content-Length: 2785 { "keys": [ { "kty": "RSA", "kid": "c8fb8b80-1193-11e3-b2b1-835742119fe8", "n": "ANxwssdcU3LbODErec3owrwUhlzjtuskAn8rAcBMRPImn5xA JRX-1T5g2D7MTozWWFk4TlpgzAR5slvM0tc35qAI9I0Cqk4Z LChQrYsWuY7alTrnNXdusHUYc6Eq89DZaH2knTcp57wAXzJP IG_tpBi5F7ck9LVRvRjybix0HJ7i4YrL-GeLuSgrjO4-GDcX Ip8oV0FMKZH-NoMfUITlWYl_JcX1D0WUAiuAnvWtD4Kh_qMJ U6FZuupZGHqPdc3vrXtp27LWgxzxjFa9qnOU6y53vCCJXLLI 5sy2fCwEDzLJqh2T6UItIzjrSUZMIsK8r2pXkroI0uYuNn3W y-jAzK8", "e": "AQAB", "x5t": "UpjRI_A3afKE8_AIeTZ5o1dECTY", "x5c": [ "MIIDgzCCAmugAwIBAgIBBjANBgkqhkiG9w0BAQUFADBGMQswCQYDV QQGEwJVUzERMA8GA1UECBMIQ29sb3JhZG8xDzANBgNVBAcTBkRlbn ZlcjETMBEGA1UEAxMKRXhhbXBsZSBDQTAeFw0xMTA3MDQwMDAwMDB aFw0xMzA3MDIyMzU5NTlaMEoxCzAJBgNVBAYTAlVTMREwDwYDVQQI EwhDb2xvcmFkbzEPMA0GA1UEBxMGRGVudmVyMRcwFQYDVQQDEw5pb S5leGFtcGxlLmNvbTCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQ oCggEBANxwssdcU3LbODErec3owrwUhlzjtuskAn8rAcBMRPImn5x Miller & Saint-Andre Expires March 10, 2014 [Page 6] Internet-Draft POSH September 2013 AJRX+1T5g2D7MTozWWFk4TlpgzAR5slvM0tc35qAI9I0Cqk4ZLChQ rYsWuY7alTrnNXdusHUYc6Eq89DZaH2knTcp57wAXzJPIG/tpBi5F 7ck9LVRvRjybix0HJ7i4YrL+GeLuSgrjO4+GDcXIp8oV0FMKZH+No MfUITlWYl/JcX1D0WUAiuAnvWtD4Kh/qMJU6FZuupZGHqPdc3vrXt p27LWgxzxjFa9qnOU6y53vCCJXLLI5sy2fCwEDzLJqh2T6UItIzjr SUZMIsK8r2pXkroI0uYuNn3Wy+jAzK8CAwEAAaN4MHYwDAYDVR0TA QH/BAIwADAdBgNVHQ4EFgQUTmRcur7xqaIUoU6wjVFPFxpf3UYwCw YDVR0PBAQDAgXgMCcGA1UdEQQgMB6gHAYIKwYBBQUHCAWgEAwOaW0 uZXhhbXBsZS5jb20wEQYJYIZIAYb4QgEBBAQDAgZAMA0GCSqGSIb3 DQEBBQUAA4IBAQBrtpz4USAT+gNWI8ccU9rFiP0Jr+76VCf8Leims qjINfKuUFxVUK5TBcCU8pyRUdXBk5THt+LUW+bPqE4SAuKjTJ1wwm e8kOqtsvrr6XDfPHyX6H7nQAaKD0VbvbHfTBKh6jNVVi+4gJACeSE JdiskoNYuJAxNDI8DmN9qAxu/8dlQHlIT3NkTxMWFUdmW8rj2xdia nfZEwuPXoI93jdpgvGhcSM92ahumFyEZ5ysK6KFsXyUmVuOQFaVsH tSAwrSGr70ASLzsCAi7JsvzO53QFW/KddkFLvEwCh/tgKK876poBo x1NI6YYuWqhcKWADOOJdSfiXeu23E25tlbDRo8", "MIIDWTCCAkGgAwIBAgIBATANBgkqhkiG9w0BAQUFADBGMQswCQYDV QQGEwJVUzERMA8GA1UECBMIQ29sb3JhZG8xDzANBgNVBAcTBkRlbn ZlcjETMBEGA1UEAxMKRXhhbXBsZSBDQTAeFw0xMTA1MDIwMDAwMDB aFw0yMzA1MTYyMzU5NTlaMEYxCzAJBgNVBAYTAlVTMREwDwYDVQQI EwhDb2xvcmFkbzEPMA0GA1UEBxMGRGVudmVyMRMwEQYDVQQDEwpFe GFtcGxlIENBMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQ EAzNQ30X7uXTg+4jKadtRO5uQEMRMnkZvDnptbWAtx0d1PsufQ2kf vog0gDhigjPEZDV9S+zm63Ia+eqJ3ROT9jDXjtF6s/IawITf5cPSN xn8qP8w+vbiy0rB4W4Nk1Dwji7KJ/wKNo0mwOx/qWNjSk3yoaU4sU EuIypizgLxKAr25vVvAJAxF6HAfdQoVAIdCZ/7qbBPI7aurdU/Ndm bbKBK0lp8aV1MYLzz8DI0hWcBQa2+gOSUcd/yT1az7UpMjGllbnVl UDxyJeCzbBaHny5NlWWHsGnsbucbM+9yeAMbRes/z0KeHxcRtomd8 bh7As12RIXKrk5GRoNVKAoiwLQIDAQABo1IwUDAPBgNVHRMBAf8EB TADAQH/MB0GA1UdDgQWBBSyiet77RfWpH3X8NMwGFVu2ldJPTALBg NVHQ8EBAMCAQYwEQYJYIZIAYb4QgEBBAQDAgAHMA0GCSqGSIb3DQE BBQUAA4IBAQBd1mMx4Wx9xFLqecbjWyy7tOE2+mrWhWxg82q7z3bB rHWjUGzolHe97Ch+6QI3+MPk9JQWYaMgYe11tyf0mgZ18NFQall4M ho2yT+E8ju11PW+RNqUdRG6rZfdeN5Geb1o1L2g5WNTdtPXoFYgHY VPQ1HmjloEic2eGnlBvOi49wAdwnASv53fgzkSJB2/GdBJ3wPIWp0 49/1vS5rsF5SJg+3mj3ZAuPYt80TRKbA/cjxEny5RfK+VJs3f7RQ/ Y3CTPxoJqskWs06/eUpjXKyzZ+MmkCs5cm1yers8goWhaI8JmLlBW LQE6v8MHdbUfb4M8la5cUd2BGtTlILOVnMv" ] } ] } 4.2. Source Domain References PKIX Certificate Miller & Saint-Andre Expires March 10, 2014 [Page 7] Internet-Draft POSH September 2013 If the source domain HTTPS server has a reference to the certificate information, it responds to the HTTPS GET with a JSON document. The document contains a "url" field whose value is the HTTPS URL where TLS clients can obtain the actual JWK set. Example Reference Response HTTP/1.1 200 Ok Content-Type: application/json Content-Length: 78 { "url":"https://hosting.example.com/.well-known/ posh.foo.json" } The client performs an HTTPS GET for the URL specified in the "url" field value. The HTTPS server for the URI at which the client has been redirected responds to the request with a JWK set. The content retrieved from the "url" location MUST NOT itself be a reference (e.g., containing only the "url" field and no "keys" field), in order to prevent circular references. Note: The JSON document returned by the source domain HTTPS server MUST contain either a reference or a JSON Web Key set, but MUST NOT contain both. 4.3. Performing Verification The TLS client compares the PKIX information obtained from the TLS server against each JWK object in the POSH results, until a match is found or the collection of POSH verification materials is exhausted. If none of the JWK objects match the TLS server PKIX information, the TLS client SHOULD reject the connection. The TLS client SHOULD compare the fingerprint of the PKIX certificate from the TLS server against the "x5t" field of the JWK object (note the "x5t" field is the base64url encoding of the fingerprint). If the "x5c" field is present instead of the "x5t" field, the TLS client generates a fingerprint of the first array element, by performing a SHA-1 hash over the PKIX certificate's DER encoding. The TLS client MAY verify the certificate chain provided in the "x5c" field of the JWK object, but it MUST NOT implicitly consider the final certificate in the "x5c" field to be a trust anchor itself; the TLS client only uses the end entity certificate information for verification. Miller & Saint-Andre Expires March 10, 2014 [Page 8] Internet-Draft POSH September 2013 5. Secure Delegation The delegation from the source domain to the delegated domain can be considered secure if the certificate offered by the TLS server matches the POSH certificate, regardless of how the POSH certificates are obtained. 6. Order of Operations In order for the TLS client to perform verification of reference identifiers without potentially compromising data, POSH processes MUST be complete before any application-level data is exchanged for the source domain. The TLS client SHOULD perform all POSH retrievals before opening any socket connections to the application protocol server. For application protocols that use DNS SRV, the POSH processes ideally ought to be done in parallel with resolving the SRV records and the addresses of any targets, similar to the "happy eyeballs" approach for IPv4 and IPv6 [RFC6555]. 7. Caching Results Ideally, the TLS client relies on the expiration time of the certificate obtained via POSH, and not on HTTP caching mechanisms. To that end, the HTTPS servers for source and derived domains SHOULD specify a 'Cache-Control' header indicating a short duration (e.g., max-age=60) or "no-cache" to indicate that the response (redirect or content) is not appropriate to cache at the HTTP level. 8. Alternates and Roll-over To indicate alternate PKIX certificates (such as when an existing certificate will soon expire), the returned JWK set MAY contain multiple JWK objects. The JWK set SHOULD be ordered with the most relevant certificate first as determined by the application service operator (e.g., the renewed certificate), followed by the next most relevant certificate (e.g., the certificate soonest to expire). Here is an example: { "keys":[ { "kty": "RSA", "kid": "cfc0ca70-1193-11e3-b2b1-835742119fe8", "n": "AM-ktWkQ8btj_HEdAA6kOpzJGgoHNZsJmxjh_PifpgAUfQeq MO_YBR100IdJZRzJfULyhRwn9bikCq87WToxgPWOnd3sH3qT YiAcIR5S6tBbsyp6WYmwM1yuC0vLCo6SoDzdK1SvkQKM3QWk 0GFNU4l4qXYAMxaSw83i6yv5DBVbST7E92vS6Gq_4pgI26l1 0JhybZuTEVPRUCG6pTKAXQpLxmjJ5oG9M91RP17nsuQeE7Ng Miller & Saint-Andre Expires March 10, 2014 [Page 9] Internet-Draft POSH September 2013 0Ap4BBn5hocojkfthwgbX4lqBMecpBAnky5jn6slmzS_rL-L w-_8hUldaTPD9MHlHPrvcsRV5uw8wK5MB6QyfS6wF4b0Kj2T vYceNlE", "e": "AQAB", "x5t": "Ae0sLVtm78VT-mQXJQop-ENOM6o", "x5c": [ "MIIDXzCCAkegAwIBAgIBAzANBgkqhkiG9w0BAQUFADBGMQswCQYDV QQGEwJVUzERMA8GA1UECBMIQ29sb3JhZG8xDzANBgNVBAcTBkRlbn ZlcjETMBEGA1UEAxMKRXhhbXBsZSBDQTAeFw0xMTA3MDQxOTUyMDB aFw0xMzA3MDMxOTUyMDBaME8xCzAJBgNVBAYTAlVTMREwDwYDVQQI EwhDb2xvcmFkbzEPMA0GA1UEBxMGRGVudmVyMRwwGgYDVQQDExNob 3N0aW5nLmV4YW1wbGUubmV0MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ 8AMIIBCgKCAQEAz6S1aRDxu2P8cR0ADqQ6nMkaCgc1mwmbGOH8+J+ mABR9B6ow79gFHXTQh0llHMl9QvKFHCf1uKQKrztZOjGA9Y6d3ewf epNiIBwhHlLq0FuzKnpZibAzXK4LS8sKjpKgPN0rVK+RAozdBaTQY U1TiXipdgAzFpLDzeLrK/kMFVtJPsT3a9Loar/imAjbqXXQmHJtm5 MRU9FQIbqlMoBdCkvGaMnmgb0z3VE/Xuey5B4Ts2DQCngEGfmGhyi OR+2HCBtfiWoEx5ykECeTLmOfqyWbNL+sv4vD7/yFSV1pM8P0weUc +u9yxFXm7DzArkwHpDJ9LrAXhvQqPZO9hx42UQIDAQABo08wTTAMB gNVHRMBAf8EAjAAMB0GA1UdDgQWBBQ/veMa6XwrIaUv8Y7PmW0RyA Um9jALBgNVHQ8EBAMCBeAwEQYJYIZIAYb4QgEBBAQDAgZAMA0GCSq GSIb3DQEBBQUAA4IBAQA7V50iyHg8+l2UBkFa8l6APKQ5zL2qN8d3 sE3mDK5a6l/597xHDxzHKMmROvHD9+MHZtYxbB0dHz1lJY0zCUAgo nfYc9J3VB4kKPB9H7u8h70pRuPudFWvQ4ZRraRPm7eSP+7/kTlOKa MCpBCiA95GKAbsbY3vQ0Hkmu5sgbIwGNs5x5V4kZSN9AfFHcmaQ2K ZufaiLjLPj6UC5CObGXjsMCWMiS7kzw8GWxnQ9viCM0uopmraMOUH cPnmtlzXparpWbiFKXGwFo1qU9QntoO71kJwVm9+ABl+lMD22WKxj 5DDutWSyxV7Nbbhni/j6HdWHNNcCNllbKzqJ54RhDoi", "MIIDWTCCAkGgAwIBAgIBATANBgkqhkiG9w0BAQUFADBGMQswCQYDV QQGEwJVUzERMA8GA1UECBMIQ29sb3JhZG8xDzANBgNVBAcTBkRlbn ZlcjETMBEGA1UEAxMKRXhhbXBsZSBDQTAeFw0xMTA1MDIwMDAwMDB 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September 2013 Y3CTPxoJqskWs06/eUpjXKyzZ+MmkCs5cm1yers8goWhaI8JmLlBW LQE6v8MHdbUfb4M8la5cUd2BGtTlILOVnMv" ] }, { "kty": "RSA", "kid": "dbc28570-1193-11e3-b2b1-835742119fe8", "n": "AM-ktWkQ8btj_HEdAA6kOpzJGgoHNZsJmxjh_PifpgAUfQeq MO_YBR100IdJZRzJfULyhRwn9bikCq87WToxgPWOnd3sH3qT YiAcIR5S6tBbsyp6WYmwM1yuC0vLCo6SoDzdK1SvkQKM3QWk 0GFNU4l4qXYAMxaSw83i6yv5DBVbST7E92vS6Gq_4pgI26l1 0JhybZuTEVPRUCG6pTKAXQpLxmjJ5oG9M91RP17nsuQeE7Ng 0Ap4BBn5hocojkfthwgbX4lqBMecpBAnky5jn6slmzS_rL-L w-_8hUldaTPD9MHlHPrvcsRV5uw8wK5MB6QyfS6wF4b0Kj2T vYceNlE", "e": "AQAB", "x5t": "lYZC2n9TBpOaUsBclEIacQTKToA", "x5c": [ "MIIDjTCCAnWgAwIBAgIBBTANBgkqhkiG9w0BAQUFADBGMQswCQYDV QQGEwJVUzERMA8GA1UECBMIQ29sb3JhZG8xDzANBgNVBAcTBkRlbnZ lcjETMBEGA1UEAxMKRXhhbXBsZSBDQTAeFw0xMzA1MTcwMDAwMDBaF w0xNTA1MTYyMzU5NTlaME8xCzAJBgNVBAYTAlVTMREwDwYDVQQIEwh Db2xvcmFkbzEPMA0GA1UEBxMGRGVudmVyMRwwGgYDVQQDExNob3N0a W5nLmV4YW1wbGUubmV0MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMII BCgKCAQEAz6S1aRDxu2P8cR0ADqQ6nMkaCgc1mwmbGOH8+J+mABR9B 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IANA Considerations This document registers a well-known URI [RFC5785] for protocols that use POSH. The completed template follows. URI suffix: posh. Change controller: IETF Specification document: [[ this document ]] Related information: Because the "posh." string is merely a prefix, protocols that use POSH need to register particular URIs that are prefixed with the "posh." string. Note that the registered URI is "posh." (with a trailing dot). This is merely a prefix to be placed at the front of well-known URIs [RFC5785] registered by protocols that use POSH, which themselves are responsible for the relevant registrations with the IANA. The URIs registered by such protocols SHOULD begin with "posh." and end with ".json" (indicating a media type of application/json [RFC4627] or application/jwk-set+json [JOSE-JWK]). For POSH-using protocols that rely on DNS SRV records [RFC2782], the part of the well-known URI between "posh." and ".json" SHOULD be Miller & Saint-Andre Expires March 10, 2014 [Page 12] Internet-Draft POSH September 2013 "{service}.{proto}", where the "{service}" is the DNS SRV "Service" prepended by the underscore character "_" and the "{proto}" is the DNS SRV "Proto" also prepended by the underscore character "_". As an example, the well-known URI for XMPP server-to-server connections would be "posh._xmpp-server._tcp.json" since XMPP [RFC6120] registers a service name of "xmpp-server" and uses TCP as the underlying transport protocol. For other POSH-using protocols, the part of the well-known URI between "posh." and ".json" can be any unique string or identifier for the protocol, which might be a service name registered with the IANA in accordance with [RFC6335] or which might be an unregistered name. As an example, the well-known URI for the mythical "Foo" service could be "posh.foo.json". Note: As explained in [RFC5785], the IANA registration policy [RFC5226] for well-known URIs is Specification Required. 10. Security Considerations This document supplements but does not supersede the security considerations provided in specifications for application protocols that decide to use POSH (e.g., [RFC6120] and [RFC6125] for XMPP). Specifically, the security of requests and responses sent via HTTPS depends on checking the identity of the HTTP server in accordance with [RFC2818]. Additionally, the security of POSH can benefit from other HTTP hardening protocols, such as HSTS [RFC6797] and key pinning [KEYPIN], especially if the TLS client shares some information with a common HTTPS implementation (e.g., platform- default web browser). Note well that POSH is used by a TLS client to obtain the public key of a TLS server to which it might connect for a particular application protocol such as IMAP or XMPP. POSH does not enable a hosted domain to transfer private keys to a hosting service via HTTPS. POSH also does not enable a TLS server to engage in certificate enrollment with a certification authority via HTTPS, as is done in Enrollment over Secure Transport [EST]. 11. References 11.1. Normative References [JOSE-JWK] Jones, M., "JSON Web Key (JWK)", draft-ietf-jose-json-web- key-14 (work in progress), July 2013. Miller & Saint-Andre Expires March 10, 2014 [Page 13] Internet-Draft POSH September 2013 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000. [RFC4627] Crockford, D., "The application/json Media Type for JavaScript Object Notation (JSON)", RFC 4627, July 2006. [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, August 2008. [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., Housley, R., and W. Polk, "Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", RFC 5280, May 2008. [RFC5785] Nottingham, M. and E. Hammer-Lahav, "Defining Well-Known Uniform Resource Identifiers (URIs)", RFC 5785, April 2010. [RFC6125] Saint-Andre, P. and J. Hodges, "Representation and Verification of Domain-Based Application Service Identity within Internet Public Key Infrastructure Using X.509 (PKIX) Certificates in the Context of Transport Layer Security (TLS)", RFC 6125, March 2011. 11.2. Informative References [EST] Pritikin, M., Yee, P., and D. Harkins, "Enrollment over Secure Transport", draft-ietf-pkix-est-09 (work in progress), August 2013. [KEYPIN] Evans, C., Palmer, C., and R. Sleevi, "Public Key Pinning Extension for HTTP", draft-ietf-websec-key-pinning-04 (work in progress), December 2012. [RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for specifying the location of services (DNS SRV)", RFC 2782, February 2000. [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "DNS Security Introduction and Requirements", RFC 4033, May 2005. Miller & Saint-Andre Expires March 10, 2014 [Page 14] Internet-Draft POSH September 2013 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008. [RFC6120] Saint-Andre, P., "Extensible Messaging and Presence Protocol (XMPP): Core", RFC 6120, March 2011. [RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S. Cheshire, "Internet Assigned Numbers Authority (IANA) Procedures for the Management of the Service Name and Transport Protocol Port Number Registry", BCP 165, RFC 6335, August 2011. [RFC6555] Wing, D. and A. Yourtchenko, "Happy Eyeballs: Success with Dual-Stack Hosts", RFC 6555, April 2012. [RFC6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication of Named Entities (DANE) Transport Layer Security (TLS) Protocol: TLSA", RFC 6698, August 2012. [RFC6797] Hodges, J., Jackson, C., and A. Barth, "HTTPS Strict Transport Security (HSTS)", RFC 6797, November 2012. Appendix A. Acknowledgements Many thanks to Philipp Hancke, Joe Hildebrand, and Tobias Markmann for their implementation feedback. Thanks also to Dave Cridland, Max Pritikin, and Joe Salowey for their input on the specification. Authors' Addresses Matthew Miller Cisco Systems, Inc. 1899 Wynkoop Street, Suite 600 Denver, CO 80202 USA Email: mamille2@cisco.com Peter Saint-Andre Cisco Systems, Inc. 1899 Wynkoop Street, Suite 600 Denver, CO 80202 USA Email: psaintan@cisco.com Miller & Saint-Andre Expires March 10, 2014 [Page 15]