Certificate Management over CMS (CMC): Transport Protocols
The information below is for an old version of the document that is already published as an RFC.
This is an older version of an Internet-Draft that was ultimately published as RFC 5273.
|Authors||Michael Myers , Jim Schaad|
|Last updated||2015-10-14 (Latest revision 2008-03-10)|
|RFC stream||Internet Engineering Task Force (IETF)|
|Additional resources||Mailing list discussion|
|IESG||IESG state||RFC 5273 (Proposed Standard)|
|Responsible AD||Tim Polk|
|Send notices to||(None)|
PKIX Working Group J. Schaad Internet-Draft Soaring Hawk Consulting Expires: September 11, 2008 M. Myers TraceRoute Security, Inc. March 10, 2008 Certificate Management over CMS (CMC): Transport Protocols draft-ietf-pkix-cmc-trans-08.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on September 11, 2008. Abstract This document defines a number of transport mechanisms that are used to move CMC (Certificate Management over CMS (Cryptographic Message Syntax)) messages. The transport mechanisms described in this document are: HTTP, file, mail and TCP. 1. Overview This document defines a number of transport methods that are used to move CMC messages (defined in [CMC-STRUCT]). The transport mechanisms described in this document are: HTTP, file, mail and TCP. Schaad & Myers Expires September 11, 2008 [Page 1] Internet-Draft CMC: Transport Protocols March 2008 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [MUST]. 2. File based protocol Enrollment messages and responses may be transferred between clients and servers using file system-based mechanisms, such as when enrollment is performed for an off-line client. When files are used to transport binary, Full PKI Request or Full PKI Response messages, there MUST be only one instance of a request or response message in a single file. The following file type extensions SHOULD be used: +---------------------+----------------+ | Message Type | File Extension | +---------------------+----------------+ | Simple PKI Request | .p10 | | Full PKI Request | .crq | | Simple PKI Response | .p7c | | Full PKI Response | .crp | +---------------------+----------------+ File PKI Request/Response Identification 3. Mail based protocol MIME wrapping is defined for those environments that are MIME native. The basic mime wrapping in this section is taken from [SMIMEV3]. When using a mail based protocol, MIME wrapping between the layers of CMS wrapping is optional. Note that is different from the standard S/MIME (Secure MIME) message. Simple enrollment requests are encoded using the "application/pkcs10" content type. A file name MUST be included either in a content type or a content disposition statement. The extension for the file MUST be ".p10". Simple enrollment response messages MUST be encoded as content-type "application/pkcs7-mime". An smime-type parameter MUST be on the content-type statement with a value of "certs-only." A file name with the ".p7c" extension MUST be specified as part of the content- type or content-disposition statement. Full enrollment request messages MUST be encoded as content-type "application/pkcs7-mime". The smime-type parameter MUST be included with a value of "CMC-enroll". A file name with the ".p7m" extension Schaad & Myers Expires September 11, 2008 [Page 2] Internet-Draft CMC: Transport Protocols March 2008 MUST be specified as part of the content-type or content-disposition statement. Full enrollment response messages MUST be encoded as content-type "application/pkcs7-mime". The smime-type parameter MUST be included with a value of "CMC-response." A file name with the ".p7m" extensions MUST be specified as part of the content-type or content- disposition statement. +--------------+------------------------+------------+--------------+ | Item | MIME TYPE | File | SMIME-TYPE | | | | Extension | | +--------------+------------------------+------------+--------------+ | Simple PKI | application/pkcs10 | .p10 | N/A | | Request | | | | | Full PKI | application/pkcs7-mime | .p7m | CMC-request | | Request | | | | | Simple PKI | application/pkcs7-mime | .p7c | certs-only | | Response | | | | | Full PKI | application/pkcs7-mime | .p7m | CMC-response | | Response | | | | +--------------+------------------------+------------+--------------+ Table 1: MIME PKI Request/Response Identification 4. HTTP/HTTPS based protocol This section describes the conventions for use of HTTP [HTTP] as a transport layer. In most circumstances, the use of HTTP over TLS [TLS] provides any necessary content protection from ease-droppers. In order for CMC clients and servers using HTTP to interoperate, the following rules apply. Clients MUST use the POST method to submit their requests. Servers MUST use the 200 response code for successful reponses. Clients MAY attempt to send HTTP requests using TLS 1.0 [TLS] or later, although servers are not required to support TLS. Servers MUST NOT assume client support for any type of HTTP authentication such as cookies, Basic authentication or Digest authentication. Clients and servers are expected to follow the other rules and restrictions in [HTTP]. Note that some of those rules are for HTTP methods other than POST; clearly, only the rules that apply to POST are relevant for this specification. Schaad & Myers Expires September 11, 2008 [Page 3] Internet-Draft CMC: Transport Protocols March 2008 4.1. PKI Request A PKI Request using the POST method is constructed as follows: The Content-Type header MUST have the appropriate value from Table 1. The body of the message is the binary value of the encoding of the PKI Request. 4.2. PKI Response An HTTP-based PKI Response is composed of the appropriate HTTP headers, followed by the binary value of the BER (Basic Encoding Rules) encoding of either a Simple or Full PKI Response. The Content-Type header MUST have the appropriate value from Table 1. 5. TCP based protocol When CMC messages are sent over a TCP-Based connection, no wrapping is required of the message. Messages are sent in their binary encoded form. The connection is closed by the client after recieving a final response. If a second round of messages is needed, the client can either re-use the same connection or use a new one. There is no specific port that is to be used when doing TCP based transport. Only the Private Ports (49152-65535) may be used in this manner (without registration). The ports in the range of (1-49151) SHOULD NOT be used. The port to be used is configured out of band. 6. Security Considerations Mechanisms for thwarting replay attacks may be required in particular implementations of this protocol depending on the operational environment. In cases where the CA maintains significant state information, replay attacks may be detectable without the inclusion of the optional nonce mechanisms. Implementers of this protocol need to carefully consider environmental conditions before choosing whether or not to implement the senderNonce and recipientNonce attributes described in section 5.6 of [CMC-STRUCT]. Developers of state-constrained PKI clients are strongly encouraged to incorporate the use of these attributes. Initiation of a secure communications channel between an end-entity Schaad & Myers Expires September 11, 2008 [Page 4] Internet-Draft CMC: Transport Protocols March 2008 and a CA or RA (and, similarly, between an RA and another RA or CA) necessarily requires an out-of-band trust initiation mechanism. For example, a secure channel may be constructed between the end-entity and the CA via IPsec [IPsec] or TLS [TLS]. Many such schemes exist and the choice of any particular scheme for trust initiation is outside the scope of this document. Implementers of this protocol are strongly encouraged to consider generally accepted principles of secure key management when integrating this capability within an overall security architecture. In some instances no prior out-of-band trust will have been initiated prior to use of this protocol. This can occur when the protocol itself is being used to download onto the system the set of trust anchors to be used for these protocols. In these instances the Enveloped Data Content type (section 220.127.116.11.3 in [CMC-STRUCT]) must be used to provide the same shrouding that TLS would have provided. 7. IANA Considerations There are no IANA considerations in this document. 8. Acknowledgments The authors and the Working Group are grateful for the participation of Xiaoui Lui and Jeff Weinstein in helping to author the original versions of this document. The authors would like to thank Brian LaMacchia for his work in developing and writing up many of the concepts presented in this document. The authors would also like to thank Alex Deacon and Barb Fox for their contributions. 9. References 9.1. Normative References [CMC-STRUCT] Schaad, J. and M. Myers, "Certificate Management Messages over CMS", draft-ietf-pkix-2797-bis-05.txt , September 2005. [HTTP] 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. Schaad & Myers Expires September 11, 2008 [Page 5] Internet-Draft CMC: Transport Protocols March 2008 [IPsec] Kent, S. and K. Seo, "Security Architecture for the Internet Protocol", RFC 4301, December 2005. [MUST] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, BCP 14, March 1997. [SMIMEV3] Ramsdell, B., "Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.1 Message Specification", RFC 3851, July 2004. 9.2. Informative References [TLS] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.1", RFC 4346, April 2006. Authors' Addresses Jim Schaad Soaring Hawk Consulting PO Box 675 Gold Bar, WA 98251 Phone: (425) 785-1031 Email: firstname.lastname@example.org Michael Myers TraceRoute Security, Inc. Email: email@example.com Schaad & Myers Expires September 11, 2008 [Page 6] Internet-Draft CMC: Transport Protocols March 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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