2.6.8 S/MIME Mail Security (smime)

Last Modified: 2003-06-06

Chair(s):
Sean Turner <turners@ieca.com>
Blake Ramsdell <blake@brutesquadlabs.com>
Security Area Director(s):
Russell Housley <housley@vigilsec.com>
Steven Bellovin <smb@research.att.com>
Security Area Advisor:
Russell Housley <housley@vigilsec.com>
Mailing Lists:
General Discussion: ietf-smime@imc.org
To Subscribe: ietf-smime-request@imc.org
Archive: http://www.imc.org/ietf-smime/
Description of Working Group:
The S/MIME Working Group has completed a series of Proposed
Standards that comprise the S/MIME version 3 specification.
Current efforts update and build upon these base specifications.

The Cryptographic Message Syntax (CMS) (RFC 3369) is cryptographic
algorithm independent, yet there is always more than one way to
use any algorithm. To ensure interoperability, each algorithm
should have a specification that describes its use with CMS.
Specifications for the use of additional cryptographic algorithms
will be developed.

As part of the specification update, a new suite of "mandatory
to implement" algorithms will be selected. These algorithms will
be reflected in updates to CERT and MSG (RFC 2632 and RFC 2633).
Building on the CMS CompressedData content type specified in
RFC 3274, the update to MSG will specify conventions for message
compression, in addition to message signature and encryption.

To aid implementers, documents containing example output for CMS
will be collected and published. Some of the examples will include
structures and signed attributes defined in the Enhanced Security
Services (ESS) (RFC 2634) document.

CMS, and thus S/MIME version 3 and later, permit the use of
previously distributed symmetric key-encryption keys. Specifications
for the distribution of symmetric key-encryption keys to multiple
message recipients will be developed. Mail List Agents (MLAs) are
one user of symmetric key-encryption keys. The specification will be
algorithm independent.

In S/MIME version 3 and later, CMS is used to provide security to the
message content if an Internet mail message. However, CMS can also
be employed in an X.400 electronic messaging envionments.
Specifications will be developed allowing this to be done in an
interoperable manner.

The working group will perform necessary interoperability testing
to progress the S/MIME specifications to Draft Standard. The CMS
specification depends on the RFC 3280, the PKIX certificate and CRL
profile. This profile must progress to Draft Standard before CMS
and the other S/MIME specification can progress to Draft Standard.
Assuming timely progress by the PKIX Working Group, the S/MIME
specification can start progressing to Draft Standard toward the
end of 2003.
Goals and Milestones:
Done  First draft of security label usage specification.
Done  First draft of CMS RecipientInfo extension.
Done  Last call on KEA and SKIPJACK algorithm specification.
Done  Last call on small subgroup attack avoidance
Done  First draft of CAST algorithm specification.
Done  Last call on certificate distribution specification.
Done  First draft of mail list key distribution.
Done  Submit KEA and SKIPJACK algorithm specification as Informational RFC.
Done  Submit small subgroup attack avoidance as Informational RFC
Done  Last call on CAST algorithm specification.
Done  Updated draft of domain security services document.
Done  Last call on security label usage specification.
Done  Last call on IDEA algorithm specification.
Done  Last call on CMS RecipientInfo extension.
Done  Last call on mail list key distribution.
Done  Submit CAST algorithm specification as Informational RFC.
Done  Submit security label usage specification as Informational RFC.
Done  Submit IDEA algorithm specification as Informational RFC.
Done  Submit CMS RecipientInfo extension to IESG for consideration as a Proposed Standard.
Done  Last call on domain security services document.
Done  Submit domain security services as Experimental RFC.
Mar 03  Submit X.400 CMS wrapper specification as a Proposed Standard
Mar 03  Submit X.400 transport as a Proposed Standard
Done  Submit mail list key distribution as a Proposed Standard
Done  Last call on CMS and ESS examples document
Done  Submit HMAC key wrap description as Proposed Standard
Done  Submit RSA OAEP algorithm specification as Proposed Standard
Done  Sumbit AES algorithm specification as Proposed Standard
Apr 03  Sumbit update to MSG as Proposed Standard
Apr 03  Sumbit update to CERT as Proposed Standard
Done  First draft of RSA KEM algorithm specification
May 03  Submit CMS and ESS examples document as Informational RFC
Jun 03  Last call on RSA PSS algorithm specification
Jul 03  Last call on RSA KEM algorithm specification
Sep 03  Submit RSA PSS algorithm specification as Proposed Standard
Oct 03  Submit RSA KEM algorithm specification as Proposed Standard
Oct 03  Final S/MIME version 3.1 interoperability matrix
Nov 03  Request advancement of CMS Algorithms to Draft Standard
Nov 03  Request advancement of CMS to Draft Standard
Dec 03  Request advancement of ESS to Draft Standard
Dec 03  Request advancement of CERT to Draft Standard
Dec 03  Request advancement of MSG to Draft Standard
Internet-Drafts:
  • - draft-ietf-smime-examples-11.txt
  • - draft-ietf-smime-symkeydist-09.txt
  • - draft-ietf-smime-x400transport-09.txt
  • - draft-ietf-smime-x400wrap-09.txt
  • - draft-ietf-smime-rfc2632bis-03.txt
  • - draft-ietf-smime-rfc2633bis-05.txt
  • - draft-ietf-smime-camellia-04.txt
  • - draft-ietf-smime-pss-01.txt
  • - draft-ietf-smime-cms-rsa-kem-00.txt
  • Request For Comments:
    S/MIME Version 2 Message Specification (RFC 2311) (70901 bytes)
    S/MIME Version 2 Certificate Handling (RFC 2312) (39829 bytes)
    Cryptographic Message Syntax (RFC 2630) (128599 bytes) obsoleted by RFC 3369
    Diffie-Hellman Key Agreement Method (RFC 2631) (25932 bytes)
    S/MIME Version 3 Certificate Handling (RFC 2632) (27925 bytes)
    S/MIME Version 3 Message Specification (RFC 2633) (67870 bytes)
    Enhanced Security Services for S/MIME (RFC 2634) (131153 bytes)
    Methods for Avoiding the 'Small-Subgroup' Attacks on the Diffie-Hellman Key Agreement Method for S/MIME (RFC 2785) (24415 bytes)
    Use of the KEA and SKIPJACK Algorithms in CMS (RFC 2876) (29265 bytes)
    Use of the CAST-128 Encryption Algorithm in CMS (RFC 2984) (11591 bytes)
    Use of the IDEA Encryption Algorithm in CMS (RFC 3058) (17257 bytes)
    Electronic Signature Policies (RFC 3125) (95505 bytes)
    Domain Security Services using S/MIME (RFC 3183) (57129 bytes)
    Electronic Signature Formats for long term electronic signatures (RFC 3126) (175886 bytes)
    Reuse of CMS Content Encryption Keys (RFC 3185) (20404 bytes)
    Triple-DES and RC2 Key Wrapping (RFC 3217) (19855 bytes)
    Password-based Encryption for SMS (RFC 3211) (30527 bytes) obsoleted by RFC 3369
    Preventing the Million Message Attack on CMS (RFC 3218) (16047 bytes)
    Use of ECC Algorithms in CMS (RFC 3278) (33779 bytes)
    Compressed Data Content Type for Cryptographic Message Syntax (CMS) (RFC 3274) (11276 bytes)
    Cryptographic Message Syntax (RFC 3369) (113975 bytes)
    Cryptographic Message Syntax (CMS) Algorithms (RFC 3370) (51001 bytes)
    Advanced Encryption Standard (AES) Key Wrap Algorithm (RFC 3394) (73072 bytes)
    Implementing Company Classification Policy with the S/MIME Security Label (RFC 3114) (27764 bytes)
    Wrapping a Hashed Message Authentication Code (HMAC) key with a Triple-Data Encryption Standard (DES) Key or an Advanced Encryption Standard (AES)Key (RFC 3537) (16885 bytes)
    Use of the RSAES-OAEP Key Transport Algorithm in Cryptographic Message Syntax (CMS) (RFC 3560) (37381 bytes)
    Use of the Advanced Encryption Standard (AES)Encryption Algorithm in Cryptographic Message Syntax (CMS) (RFC 3565) (26773 bytes)

    Current Meeting Report

    revision.Minutes for S/MIME Meeting
    IETF 57
    July 14, 2003
    
    Agenda: Sean Turner covered the agenda for the meeting. No changes were 
    made.
    
    Working Group Status: Sean Turner covered the status of the active 
    documents in the working group. The documents that have changed status 
    since the last meeting are:
    
    Published as RFC:
    - 3395 Implementing Company Classification Policy with S/MIME Security 
    Label.
    - 3537 Wrapping a Hashed Message Authentication Code (HMAC) key with 
    Triple-Data Encryption Standard (DES) Key or an Advanced Encryption 
    Standard (AES) Keys.
    
    RFC Editor Queue:
    - aes-alg Use of the AES Encryption Algorithm in CMS.
    - cms-rsaes-oaep Use of RSAE-OAEP Key Transport Algorithm in CMS.
    
    With IESG:
    - Camellia Use of Camellia Encryption Algorithm in CMS.
    
    CMS and ESS Examples Draft: Paul Hoffman explained that new examples have 
    been added to the –11 draft, all of which need to be verified. After 
    verification by all, a new -12 will be issued and the ADs will be asked to 
    issue an IETF last call.
    
    MSGbis and CERTbis: Sean Turner presented Blake Ramsdell's 
    presentation.  In MSGbis minor edits were included, id-dsa was changed to 
    id-dsa-with-sha1, and AES was made a SHOULD. MSGbis is ready for an IETF 
    last call.  In CERTbis text is still needed for acknowlegements and a 
    summary of changes to the draft. There was an issue as to whether 
    smime-types for every know CMS type should be included in the 
    document. It was decided that the smime-types currently in the draft will 
    remain but any new ones will be placed in new drafts so as to not hold up 
    MSGbis.
    
    X400WRAP and X400TRANS: Chris Bonatti explained that changes similar to 
    those in MSGbis were also made to X400WRAP - id-dsa was changed to 
    id-dsa-with-sha1, and AES was made a SHOULD. In X400TRANS, the security 
    considerations section was updated, as a result of IESG comments, to 
    indicate that no new security concerns are added other than those in CMS or 
    S/MIME models. It is believed that both documents are now ready for IETF 
    last call.
    
    Interoperability Matrix: Jim Schaad indicated that the tests for both 
    SignedData and EncryptedData are complete and that only the final 
    write-up is required. The only remaining issues are with the Key 
    Derivation Algorithm - PBKDF2 and the Message Authentication Code 
    Algorithm - HMAC with SHA-1 neither of which were tested will result in 
    blocking the draft.
    
    RSA KEM: Jim Schaad presented an overview of the RSA KEM algorithm. The 
    remaining issues to complete the draft are defining matching rules for 
    usage, SMIMECapabilities attribute values, and a single ASN.1 module.
    
    RSA PSS: Jim Schaad presented an overview of the RSA PSS algorithm. The 
    requirements for the parameters H1 (digest hash algorithm 
    parameters) and H2 (internal hash algorithm parameters) SHOULD be the 
    same, and H2 and H3 (message generation function hash algorithm 
    parameters) are RECOMMENDED to be the same. The resolved outstanding 
    issues are that the key identifier and signature identifier will be the 
    same OID and that PSS parameter comparison MUST be done if they are 
    present in the certificate. It is believed that his draft is ready for WG 
    last call.
    
    ESSbis: Jim Schaad presented updates to ESS which included splitting the 
    MLExpansionHistory attribute in to two new attributes - Receipt 
    Behavior and ML Loop Detection. The work required to rewrite the 
    processing rules is proving more difficult that originally thought. Jim 
    also indicated that there were outstanding issues on the list that deal 
    with nested cases for receipt processing and MLA attribute 
    propagation.
    
    GOST Algorithm: Grigory Chudov presented the Russian national 
    algorithm GOST and an individual submission explaining how CMS can be used 
    with GOST. The WG agreed to publish the draft under the WG banner.
    
    OpenEvidence Project and ESS: Peter Sylvester explained a usage of the 
    technology developed in the OpenEvidence project, an open source 
    projects financed by the European commission and run by a small group of 
    European companies. A useful application of the technology addresses the 
    problem to make email more reliable by using a third party security 
    infrastructure to provide more traceability for users, service 
    providers, and organizations. The tools developed were based on 
    existing standards, i.e., SMIME signed receipts and RFC 3029. Two of the 
    outputs of the project are the realization that there are few toolkits to 
    provide support for ESS and that the ASN.1, which is 88 based, is 
    problematic for new compilers. (A more detailed presentation of 
    OpenEvidence project has been made in the PKIX wg).
    
    NIST S/MIME Tester: Tim Polk discussed the NIST online S/MIME tester that is 
    intended to test the conformance of S/MIME implementations to the NIST 
    S/MIME profile. More information can be found at: 
    http://csrc.nist.gov/pki/smime/smtest.htm.
    
    
    

    Slides

    Agenda
    Russian cryptographic algorithms (GOST) in Cryptographic Message Syntax and S/MIME
    CMS Interoperability Matrix
    S/MIME CERT and MSG
    OpenEvidence and ESS
    NIST S/MIME Testing Facility
    S/MIME Working Group Status
    S/MIME CMS-X.400 Drafts: Status & Issues
    S/MIME Examples Document Status report