Internet Draft Ronald Tschal„r (Trustpoint) PKIX Working Group Amit Kapoor (Trustpoint) Expires in 6 months Carlisle Adams (Entrust Technologies) Aug. 1999 Using HTTP as a Transport Protocol for CMP Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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 February 5, 2000 Copyright Notice Copyright (C)The Internet Society (1999). All Rights Reserved. Abstract This document describes how to layer [CMP] over [HTTP]. A simple method for doing so is described in section 5.4 of [CMP], but that method does not accommodate a polling mechanism, which may be required in some environments. This document specifies an alternative method which uses the polling protocol defined in section 5.2 of [CMP]. A new Content-Type for messages is also defined. The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document (in uppercase, as shown) are to be interpreted as described in [RFC2119]. 1. Motivation Section 5.4 of the CMP spec specifies sending the DER-encoded CMP message directly over HTTP. However, because the method described there does not define a polling mechanism, the server is required to send a final response immediately. This may be impossible for environments in which manual intervention is needed in the registration/certification process (and, for practical reasons, a connection cannot be left open indefinitely until the manual activity is complete). On the other hand, section 5.2 of [CMP] defines a simple protocol over TCP that allows polling. This protocol can be used over HTTP in a straightforward way, solving the above problem and simplifying implementations that support multiple protocols. 2. Specification A client creates a "direct TCP-based PKI message", henceforth referred to simply as "message", as specified in section 5.2 of [CMP]. The message is then sent as the entity-body of an HTTP POST request. If the HTTP request is successful then the server returns a similar message in the body of the response. The response status code in this case MUST be 200; other 2xx codes MUST NOT be used. The content type of the request and response MUST be "application/pkixcmp-poll". Content codings may be applied. Note that a server may return any 1xx, 3xx, 4xx, or 5xx code if the HTTP request needs further handling or is otherwise not acceptable. 3. Discussion The protocol defined in section 5.2 of [CMP] provides a means for letting the client poll for the response. It also defines a response for every request, which maps well onto HTTP's request-response nature. By using the exact same messages as section 5.2, client and server implementations that handle CMP messages over both TCP and HTTP are simplified. A new content type is introduced so as to avoid confusion with the protocol defined in section 5.4 of [CMP]. It is recommended that the section 5.4 specification be phased out in favour of the one described in this document. Because in general CMP message are not cacheable, requests and responses should include a "Cache-Control: no-cache" (and, if either side uses HTTP/1.0, a "Pragma: no-cache") to prevent the client from getting cached responses. This is especially important for polling requests and responses. 4. Security Considerations No new security considerations with respect to [CMP] are introduced. References [CMP] Adams, C., Farrell, S., "Internet X.509 Public Key Infrastructure, Certificate Management Protocols", RFC 2510, March 1999. [HTTP] Fielding, R.T., et. al, "Hypertext Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997. Authors' Addresses Amit Kapoor Trustpoint 429 Castro Street, Suite B Mountain View, CA 94041 US E-Mail: amit@trustpoint.com Ronald Tschal„r Trustpoint 429 Castro Street, Suite B Mountain View, CA 94041 US E-Mail: ronald@trustpoint.com Carlisle Adams Entrust Technologies 750 Heron Road, Suite E08, Ottawa, Ontario Canada K1V 1A7 E-Mail: cadams@entrust.com Appendix A: Registration of MIME Type for Section 2 To: ietf-types@iana.org Subject: Registration of MIME media type application/pkixcmp-poll MIME media type name: application MIME subtype name: pkixcmp-poll Required parameters: none Optional parameters: none Encoding considerations: Content may contain arbitrary octet values (the ASN.1 DER encoding of a PKI message, as defined in the IETF PKIX Working Group specifications). base64 encoding is required for MIME e-mail; no encoding is necessary for HTTP. Security considerations: This MIME type may be used to transport Public-Key Infrastructure (PKI) messages between PKI entities. These messages are defined by the IETF PKIX Working Group and are used to establish and maintain an Internet X.509 PKI. There is no requirement for specific security mechanisms to be applied at this level if the PKI messages themselves are protected as defined in the PKIX specifications. Interoperability considerations: - Published specification: this document Applications which use this media type: Applications using certificate management, operational, or ancillary protocols (as defined by the IETF PKIX Working Group) to send PKI messages via e-mail or HTTP. Additional information: Magic number (s): - File extension (s): ".PKI" Macintosh File Type Code (s): - Person and email address to contact for further information: Carlisle Adams, cadams@entrust.com Intended usage: COMMON Author/Change controller: Carlisle Adams Full Copyright Statement Copyright (C) The Internet Society (1999). All Rights Reserved. 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