Internet Engineering Task Force (IETF) S. Turner
Request for Comments: 5967 IECA
Updates: 2986 August 2010
The application/pkcs10 Media Type
This document specifies a media type used to carry PKCS #10
certification requests as defined in RFC 2986. It carries over the
original specification from RFC 2311, which recently has been moved
to Historic status, and properly links it to RFC 2986.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
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[RFC2311] first defined the application/pkcs10 media type. When
[RFC2633] was published, the application/pkcs10 section was dropped,
but for some reason the text was not incorporated into the PKCS #10
document [RFC2986]. [RFC2311] was moved to Historic status by
[RFC5751]. To ensure the IANA media type registration points to a
non-Historic document, this document updates [RFC2986] with the
definition of the application/pkcs10 media type and an IANA
registration based on [RFC4288].
The text for Section 2 is adapted from Section 3.7 of [RFC2311].
1.1. Requirements Terminology
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 [RFC2119].
2. Creating a Certification Request
A typical application that allows a user to generate cryptographic
information has to submit that information to a Certification
Authority (CA), who transforms it into a certificate. PKCS #10
[RFC2986] describes a syntax for certification requests.
The details of certification requests and the process of obtaining a
certificate are beyond the scope of this memo. Instead, only the
format of data used in application/pkcs10 is defined.
2.1. Format of the application/pkcs10 Body
PKCS #10 defines the ASN.1 type CertificationRequest for use in
submitting a certification request. For transfer to a CA, this
abstract syntax needs to be encoded and identified in a unique
manner. When the media type application/pkcs10 is used, the body
MUST be a CertificationRequest.
A robust application SHOULD output Distinguished Encoding Rules
(DER), but allow Basic Encoding Rules (BER) or DER on input.
Data produced by BER or DER is 8-bit, but some transports are limited
to 7-bit data. In such cases, a suitable 7-bit transfer encoding
MUST be applied; in MIME-compatible transports, the base64 encoding
[RFC4648] SHOULD be used with application/pkcs10, although any 7-bit
transfer encoding may work.
2.2. Sending and Receiving an application/pkcs10 Body Part
For sending a certificate-signing request, the application/pkcs10
message format MUST be used to convey a PKCS #10 certificate-signing
request. Note that for sending certificates and Certificate
Revocation Lists (CRLs) without any signed content, the
application/pkcs7-mime message format MUST be used to convey a
degenerate PKCS #7 signedData "certs-only" message [RFC5751].
To send an application/pkcs10 body, the application generates the
cryptographic information for the user. The details of the
cryptographic information are beyond the scope of this memo.
Step 1. The cryptographic information is placed within a PKCS #10
Step 2. The CertificationRequest is encoded according to BER or DER
Step 3. As a typical step, the encoded CertificationRequest is also
base64 encoded so that it is 7-bit data suitable for transfer
in ESMTP. This then becomes the body of an
application/pkcs10 body part.
The result might look like this:
Content-Type: application/pkcs10; name=smime.p10
Content-Disposition: attachment; filename=smime.p10
A typical application only needs to send a certification request. It
is a Certification Authority that has to receive and process the
request. The steps for recovering the CertificationRequest from the
message are straightforward but are not presented here. The
procedures for processing the certification request are beyond the
scope of this document.
3. IANA Considerations
IANA has updated the registration for the application/pkcs10 media
subtype in the Application Media Types registry using the filled-in
template from BCP 13 [RFC4288] given below.
3.1. Registration of Media Subtype application/pkcs10
The media subtype for a PKCS #10 certification request is
Type name: application
Subtype name: pkcs10
Required parameters: None
Optional parameters: None
Encoding considerations: binary; see Section 2.
Clients use a certification request to request that a
Certification Authority certify a public key. The
certification request is digitally signed. Also, see
Interoperability considerations: See Section 2.
Published specification: This specification.
Applications which use this media type:
Applications that support PKCS #10 certification requests
Magic number(s): None
File extension(s): .p10
Macintosh File Type Code(s):
Person & email address to contact for further information:
Sean Turner <firstname.lastname@example.org>
Restrictions on usage: none
Author: Sean Turner <email@example.com>
Intended usage: COMMON
Change controller: The IESG
4. Security Considerations
The security considerations of [RFC2986] and [RFC5751] apply; no new
security considerations are introduced by this document.
I wish to thank the authors of RFC 2311, Steve Dusse, Paul Hoffman,
Blake Ramsdell, Laurence Lundblade, and Lisa Repka.
I would also like to thank Bjoern Hoehrmann for his review of the
media subtype application.
6.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2986] Nystrom, M. and B. Kaliski, "PKCS #10: Certification
Request Syntax Specification Version 1.7", RFC 2986,
[RFC4288] Freed, N. and J. Klensin, "Media Type Specifications and
Registration Procedures", BCP 13, RFC 4288, December 2005.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, October 2006.
[RFC5751] Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet
Mail Extensions (S/MIME) Version 3.2 Message
Specification", RFC 5751, January 2010.