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Authentication-Results Registration for S/MIME signature verification
draft-melnikov-authentication-results-smime-03

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This is an older version of an Internet-Draft that was ultimately published as RFC 7281.
Author Alexey Melnikov
Last updated 2013-10-11
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draft-melnikov-authentication-results-smime-03
Network Working Group                                        A. Melnikov
Internet-Draft                                                 Isode Ltd
Intended status: Standards Track                        October 11, 2013
Expires: April 14, 2014

 Authentication-Results Registration for S/MIME signature verification
             draft-melnikov-authentication-results-smime-03

Abstract

   RFC 7001 specifies the Authentication-Results header field for
   conveying results of message authentication checks.  This document
   defines a new authentication method to be used in the Authentication-
   Results header field for S/MIME related signature checks.

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 April 14, 2014.

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.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   2
   3.  "smime" Authentication Method . . . . . . . . . . . . . . . .   2
     3.1.  S/MIME Results  . . . . . . . . . . . . . . . . . . . . .   2
     3.2.  Examples  . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Appendix A.  Acknowledgements . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   [RFC7001] specifies the Authentication-Results header field for
   conveying results of message authentication checks.  As S/MIME
   signature verification (and alteration) is sometimes implemented in
   border message transfer agents, guards and gateways (for example see
   [RFC3183]), there is a need to convey signature verification status
   to Mail User Agents (MUA) and downstream filters.  This document
   defines a new authentication method to be used in the Authentication-
   Results header field for S/MIME related signature checks.

2.  Conventions Used in This Document

   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].

   The formal syntax uses the Augmented Backus-Naur Form (ABNF)
   [RFC5234] notation including the core rules defined in Appendix B of
   RFC 5234 [RFC5234].

3.  "smime" Authentication Method

3.1.  S/MIME Results

   The result values used by [RFC5751] are as follows:

   +-------------+-----------------------------------------------------+
   | Result code | Meaning                                             |
   +-------------+-----------------------------------------------------+
   | none        | The message was not signed.                         |
   |             |                                                     |
   | pass        | The message was signed, the signature or signatures |
   |             | were acceptable to the verifier, and the            |

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   |             | signature(s) passed verification tests.             |
   |             |                                                     |
   | fail        | The message was signed and the signature or         |
   |             | signatures were acceptable to the verifier, but     |
   |             | they failed the verification test(s).               |
   |             |                                                     |
   | policy      | The message was signed, signature(s) passed         |
   |             | verification tests, but the signature or signatures |
   |             | were not acceptable to the verifier.                |
   |             |                                                     |
   | neutral     | The message was signed but the signature or         |
   |             | signatures contained syntax errors or were not      |
   |             | otherwise able to be processed.  This result SHOULD |
   |             | also be used for other failures not covered         |
   |             | elsewhere in this list.                             |
   |             |                                                     |
   | temperror   | The message could not be verified due to some error |
   |             | that is likely transient in nature, such as a       |
   |             | temporary inability to retrieve a certificate or    |
   |             | CRL.  A later attempt may produce a final result.   |
   |             |                                                     |
   | permerror   | The message could not be verified due to some error |
   |             | that is unrecoverable, such as a required header    |
   |             | field being absent or the signer's certificate not  |
   |             | being available.  A later attempt is unlikely to    |
   |             | produce a final result.                             |
   +-------------+-----------------------------------------------------+

   A signature is "acceptable to the verifier" if it passes local policy
   checks (or there are no specific local policy checks).  For example,
   a verifier might require that the domain in the rfc822Name
   subjectAltName in the signing certificate matches the domain in the
   address of the sender of the message, thus making third-party
   signatures unacceptable.  [RFC5751] advises that if a message fails
   verification, it should be treated as an unsigned message.  A report
   of "fail" here permits the receiver of the report to decide how to
   handle the failure.  A report of "neutral" or "none" preempts that
   choice, ensuring the message will be treated as if it had not been
   signed.

3.2.  Examples

   Return-Path: <aliceDss@examples.com>
   Authentication-Results: example.com;
    smime=fail (certificate is revoked by CRL)
    body.smime-identifier=aliceDss@examples.com
    body.smime-part=2

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   Received: from ietfa.amsl.com (localhost [IPv6:::1])
       by ietfa.amsl.com (Postfix) with ESMTP id 2875111E81A0;
       Fri, 06 Sep 2002 00:35:14 -0700 (PDT)
   MIME-Version: 1.0
   To: User2@examples.com
   From: aliceDss@examples.com
   Subject: Example 4.8
   Message-Id: <020906002550300.249@examples.com>
   Date: Fri, 06 Sep 2002 00:25:21 -0700
   Content-Type: multipart/signed;
       micalg=SHA1;
       boundary="----=_NextBoundry____Fri,_06_Sep_2002_00:25:21";
       protocol="application/pkcs7-signature"

   This is a multi-part message in MIME format.

   ------=_NextBoundry____Fri,_06_Sep_2002_00:25:21

   This is some sample content.
   ------=_NextBoundry____Fri,_06_Sep_2002_00:25:21
   Content-Type: application/pkcs7-signature; name=smime.p7s
   Content-Transfer-Encoding: base64
   Content-Disposition: attachment; filename=smime.p7s

   MIIDdwYJKoZIhvcNAQcCoIIDaDCCA2QCAQExCTAHBgUrDgMCGjALBgkqhkiG9w0BBwGgggL
   gMIIC3DCCApugAwIBAgICAMgwCQYHKoZIzjgEAzASMRAwDgYDVQQDEwdDYXJsRFNTMB4XDT
   k5MDgxNzAxMTA0OVoXDTM5MTIzMTIzNTk1OVowEzERMA8GA1UEAxMIQWxpY2VEU1MwggG2M
   IIBKwYHKoZIzjgEATCCAR4CgYEAgY3N7YPqCp45PsJIKKPkR5PdDteoDuxTxauECE//lOFz
   SH4M1vNESNH+n6+koYkv4dkwyDbeP5u/t0zcX2mK5HXQNwyRCJWb3qde+fz0ny/dQ6iLVPE
   /sAcIR01diMPDtbPjVQh11Tl2EMR4vf+dsISXN/LkURu15AmWXPN+W9sCFQDiR6YaRWa4E8
   baj7g3IStii/eTzQKBgCY40BSJMqo5+z5t2UtZakx2IzkEAjVc8ssaMMMeUF3dm1nizaoFP
   VjAe6I2uG4Hr32KQiWn9HXPSgheSz6Q+G3qnMkhijt2FOnOLl2jB80jhbgvMAF8bUmJEYk2
   RL34yJVKU1a14vlz7BphNh8Rf8K97dFQ/5h0wtGBSmA5ujY5A4GEAAKBgFzjuVp1FJYLqXr
   d4z+p7Kxe3L23ExE0phaJKBEj2TSGZ3V1ExI9Q1tv5VG/+onyohs+JH09B41bY8i7RaWgSu
   OF1s4GgD/oI34a8iSrUxq4Jw0e7wi/ZhSAXGKsZfoVi/G7NNTSljf2YUeyxDKE8H5BQP1Gp
   2NOM/Kl4vTyg+W4o4GBMH8wDAYDVR0TAQH/BAIwADAOBgNVHQ8BAf8EBAMCBsAwHwYDVR0j
   BBgwFoAUcEQ+gi5vh95K03XjPSC8QyuT8R8wHQYDVR0OBBYEFL5sobPjwfftQ3CkzhMB4v3
   jl/7NMB8GA1UdEQQYMBaBFEFsaWNlRFNTQGV4YW1wbGUuY29tMAkGByqGSM44BAMDMAAwLQ
   IUVQykGR9CK4lxIjONg2q1PWdrv0UCFQCfYVNSVAtcst3a53Yd4hBSW0NevTFjMGECAQEwG
   DASMRAwDgYDVQQDEwdDYXJsRFNTAgIAyDAHBgUrDgMCGjAJBgcqhkjOOAQDBC4wLAIUM/mG
   f6gkgp9Z0XtRdGimJeB/BxUCFGFFJqwYRt1WYcIOQoGiaowqGzVI

   ------=_NextBoundry____Fri,_06_Sep_2002_00:25:21--

4.  IANA Considerations

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   IANA is requested to add the the following entries to the "Email
   Authentication Methods" subregistry of the "Email Authentication
   Parameters" registry:

   +--------+-----------+--------+------------------+------------------+
   | Method | Defined   | ptype  | property         | value            |
   +--------+-----------+--------+------------------+------------------+
   | smime  | [RFC5751] | body   | smime-part       | The MIME body    |
   |        |           |        |                  | part reference   |
   |        |           |        |                  | which contains   |
   |        |           |        |                  | the signature.   |
   |        |           |        |                  | See definition   |
   |        |           |        |                  | of <section> in  |
   |        |           |        |                  | Section 6.4.5 of |
   |        |           |        |                  | [RFC3501]        |
   |        |           |        |                  |                  |
   | smime  | [RFC5751] | body   | smime-identifier | The email        |
   |        |           |        |                  | address          |
   |        |           |        |                  | [RFC5322]        |
   |        |           |        |                  | associated with  |
   |        |           |        |                  | the S/MIME       |
   |        |           |        |                  | signature.  Note |
   |        |           |        |                  | that this email  |
   |        |           |        |                  | address can      |
   |        |           |        |                  | correspond to a  |
   |        |           |        |                  | counter          |
   |        |           |        |                  | signature.       |
   +--------+-----------+--------+------------------+------------------+

   IANA is requested to add the the following entries to the "Email
   Authentication Result Names" subregistry of the "Email Authentication
   Parameters" registry:

   +-------------+--------------+------------+---------------+---------+
   | Code        | Defined      | Auth       | Meaning       | Status  |
   |             |              | Method     |               |         |
   +-------------+--------------+------------+---------------+---------+
   | none        | this         | smime      | [this memo]   | active  |
   |             | document     |            | Section 3.1   |         |
   |             |              |            |               |         |
   | pass        | this         | smime      | [this memo]   | active  |
   |             | document     |            | Section 3.1   |         |
   |             |              |            |               |         |
   | fail        | this         | smime      | [this memo]   | active  |
   |             | document     |            | Section 3.1   |         |
   |             |              |            |               |         |
   | policy      | this         | smime      | [this memo]   | active  |

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   |             | document     |            | Section 3.1   |         |
   |             |              |            |               |         |
   | neutral     | this         | smime      | [this memo]   | active  |
   |             | document     |            | Section 3.1   |         |
   |             |              |            |               |         |
   | temperror   | this         | smime      | [this memo]   | active  |
   |             | document     |            | Section 3.1   |         |
   |             |              |            |               |         |
   | permerror   | this         | smime      | [this memo]   | active  |
   |             | document     |            | Section 3.1   |         |
   +-------------+--------------+------------+---------------+---------+

5.  Security Considerations

   This document doesn't add new security considerations not already
   covered by [RFC7001] and [RFC5751].  In particular security
   considerations related to use of weak cryptography over plaintext,
   weakening and breaking of cryptographic algorithms over time, as well
   as changing the behavior of message processing based on presence of a
   signature specified in [RFC5751] are relevant to this document.
   Similarly, the following security considerations specified in
   [RFC7001] are particularly relevant to this document: Forged Header
   Fields, Misleading Results, Internal MTA Lists and Compromised
   Internal Hosts.

6.  References

6.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3501]  Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION
              4rev1", RFC 3501, March 2003.

   [RFC5234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234, January 2008.

   [RFC5322]  Resnick, P., Ed., "Internet Message Format", RFC 5322,
              October 2008.

   [RFC7001]  Kucherawy, M., "Message Header Field for Indicating
              Message Authentication Status", RFC 7001, September 2013.

   [RFC5751]  Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet
              Mail Extensions (S/MIME) Version 3.2 Message
              Specification", RFC 5751, January 2010.

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6.2.  Informative References

   [RFC3183]  Dean, T. and W. Ottaway, "Domain Security Services using S
              /MIME", RFC 3183, October 2001.

Appendix A.  Acknowledgements

   Thank you to Murray S. Kucherawy, David Wilson and Steve Kille for
   comments and corrections on this document.

Author's Address

   Alexey Melnikov
   Isode Ltd
   5 Castle Business Village
   36 Station Road
   Hampton, Middlesex  TW12 2BX
   UK

   EMail: Alexey.Melnikov@isode.com

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