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Using SHA2 Algorithms with Cryptographic Message Syntax
draft-ietf-smime-sha2-11

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This is an older version of an Internet-Draft that was ultimately published as RFC 5754.
Author Sean Turner
Last updated 2020-01-21 (Latest revision 2009-01-20)
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draft-ietf-smime-sha2-11
S/MIME WG                                             Sean Turner, IECA 
Internet Draft                                         January 16, 2009 
Intended Status: Standard Track 
Updates: 3370 (once approved) 
Expires: July 16, 2009 
 
                                      
          Using SHA2 Algorithms with Cryptographic Message Syntax 
                       draft-ietf-smime-sha2-11.txt 

Status of this Memo 

   This Internet-Draft is submitted to IETF in full conformance with the 
   provisions of BCP 78 and BCP 79. 

   Internet-Drafts are working documents of the Internet Engineering 
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   This Internet-Draft will expire on July 16, 2009. 

Copyright Notice 

   Copyright (c) 2009 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 
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   publication of this document.  Please review these documents 
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   to this document. 

 
 
 
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Abstract 

   This document describes the conventions for using the Secure Hash 
   Algorithm (SHA) message digest algorithms (SHA-224, SHA-256, SHA-384, 
   SHA-512) with the Cryptographic Message Syntax (CMS). It also 
   describes the conventions for using these algorithms with CMS and the 
   Digital Signature Algorithm (DSA), Rivest Shamir Adleman (RSA), and 
   Elliptic Curve DSA (ECDSA) signature algorithms.  Further, it 
   provides SMIMECapabilities attribute values for each algorithm. 

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]. 

Table of Contents 

   1. Introduction...................................................2 
   2. Message Digest Algorithms......................................3 
      2.1. SHA-224...................................................4 
      2.2. SHA-256...................................................5 
      2.3. SHA-384...................................................5 
      2.4. SHA-512...................................................5 
   3. Signature Algorithms...........................................6 
      3.1. DSA.......................................................6 
      3.2. RSA.......................................................7 
      3.3. ECDSA.....................................................8 
   4. Security Considerations........................................9 
   5. IANA Considerations............................................9 
   6. References....................................................10 
      6.1. Normative References.....................................10 
      6.2. Informative References...................................11 
    
1. Introduction 

   This document specifies the algorithm identifiers and specifies 
   parameters for the message digest algorithms SHA-224, SHA-256, SHA-
   384, and SHA-512 for use with the Cryptographic Message Syntax (CMS) 
   [RFC3852].  The message digest algorithms are defined in [SHS] and 
   reference code is provided in [RFC4634]. 

   This document also specifies the algorithm identifiers and parameters 
   for use of SHA-224, SHA-256, SHA-384, and SHA-512 with DSA [DSS], RSA 
   (RSASSA-PKCS1-v1_5) [RFC3447], and ECDSA [DSS]. 

 
 
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   This document does not define new identifiers; they are taken from 
   [RFC3874], [RFC4055], and [ECCADD].  Additionally, the parameters 
   follow the conventions specified therein.  Therefore, there is no 
   Abstract Syntax Notation One (ASN.1) module included in this 
   document. 

   Note that [RFC4231] specifies the conventions for the message 
   authentication code (MAC) algorithms: HMAC with SHA-224, HMAC with 
   SHA-256, HMAC with SHA-384, and HMAC with SHA-512. 

   In CMS, the various algorithm identifiers use the AlgorithmIdentifier 
   syntax, which is included here for convenience: 

     AlgorithmIdentifier  ::=  SEQUENCE  { 
       algorithm   OBJECT IDENTIFIER, 
       parameters  ANY DEFINED BY algorithm OPTIONAL  } 

   This document also specifies the SMIMECapabilities attribute values 
   [RFCTBD1] for each algorithm.  The values provided are for the 
   SMIMECapability field, which is included here for convenience: 

     SMIMECapability ::= SEQUENCE { 
       capabilityID  OBJECT IDENTIFIER, 
       parameters    ANY DEFINED BY capabilityID OPTIONAL } 

2. Message Digest Algorithms 

   Digest algorithm identifiers are located in the SignedData 
   digestAlgorithms field, the SignerInfo digestAlgorithm field, the 
   DigestedData digestAlgorithm field, and the AuthenticatedData 
   digestAlgorithm field.  The object identifiers are taken from 
   [RFC4055]. 

   Digest values are located in the DigestedData digest field and the 
   Message Digest authenticated attribute.  In addition, digest values 
   are input to signature algorithms. 

   The digest algorithm identifiers use the AlgorithmIdentifier syntax 
   elaborated upon in Section 1. 

   The algorithm field and SMIMECapabilities attribute are discussed in 
   Sections 2.1-2.4 for each message digest algorithm.  Section 3 
   provides some signatures that use SHA2 algorithms.  Consult the 
   signature algorithm definitions for the procedures to compute the 
   digest values (i.e., DigestInfo). 

 
 
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   The AlgorithmIdentifier parameters field is OPTIONAL.  
   Implementations MUST accept SHA2 AlgorithmIdentifiers with absent 
   parameters.  Implementations MUST accept SHA2 AlgorithmIdentifiers 
   with NULL parameters.  Implementations MUST generate SHA2 
   AlgorithmIdentifiers with absent parameters. 

   NOTE: There are two possible encodings for the AlgorithmIdentifier 
   parameters field associated with these object identifiers.  The two 
   alternatives arise from the loss of the OPTIONAL associated with the 
   algorithm identifier parameters when the 1988 syntax for 
   AlgorithmIdentifier was translated into the 1997 syntax.  Later the 
   OPTIONAL was recovered via a defect report, but by then many people 
   thought that algorithm parameters were mandatory.  Because of this 
   history some implementations encode parameters as a NULL element 
   while others omit them entirely.  The correct encoding is to omit the 
   parameters field; however, when some uses of these algorithms were 
   defined, it was done using the NULL parameters rather than absent 
   parameters.  For example, PKCS#1 [RFC3447] requires that the padding 
   used for RSA signatures (EMSA-PKCS1-v1_5) MUST use SHA2 
   AlgorithmIdentifiers with NULL parameters (to clarify, the 
   requirement "MUST generate SHA2 AlgorithmIdentifiers with absent 
   parameters" in the previous paragraph does not apply to this 
   padding). 

2.1. SHA-224 

   The SHA-224 message digest algorithm is defined in [SHS].  The 
   algorithm identifier for SHA-224 is: 

     id-sha224 OBJECT IDENTIFIER ::= { 
        joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101) 
        csor(3) nistalgorithm(4) hashalgs(2) 4 } 

   The parameters are as specified in Section 2. 

   The SMIMECapabilities attribute value indicates support for SHA-224 
   in a SEQUENCE with the capabilityID field containing the object 
   identifier id-sha224 with absent parameters.  The DER encoding for 
   this SMIMECapability is: 

      id-sha224: 30 0b 06 09 60 86 48 01 65 03 04 02 04 

 
 
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2.2. SHA-256 

   The SHA-256 message digest algorithm is defined in [SHS].  The 
   algorithm identifier for SHA-256 is: 

    id-sha256 OBJECT IDENTIFIER ::= { 
        joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101) 
        csor(3) nistalgorithm(4) hashalgs(2) 1 } 

   The parameters are as specified in Section 2. 

   The SMIMECapabilities attribute value indicates support for SHA-256 
   in a SEQUENCE with the capabilityID field containing the object 
   identifier id-sha256 with absent parameters.  The DER encoding for 
   this SMIMECapability value is: 

      id-sha256: 30 0b 06 09 60 86 48 01 65 03 04 02 01 

2.3. SHA-384 

   The SHA-384 message digest algorithm is defined in [SHS].  The 
   algorithm identifier for SHA-384 is: 

     id-sha384 OBJECT IDENTIFIER ::= { 
       joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101) 
       csor(3) nistalgorithm(4) hashalgs(2) 2 } 

   The parameters are as specified in Section 2. 

   The SMIMECapabilities attribute value indicates support for SHA-384 
   in a SEQUENCE with the capabilityID field containing the object 
   identifier id-sha384 with absent parameters.  The DER encoding for 
   this SMIMECapability value is: 

      id-sha384: 30 0b 06 09 60 86 48 01 65 03 04 02 02 

2.4. SHA-512 

   The SHA-512 message digest algorithm is defined in [SHS].  The 
   algorithm identifier for SHA-512 is: 

     id-sha512 OBJECT IDENTIFIER ::= { 
       joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101) 
       csor(3) nistalgorithm(4) hashalgs(2) 3 } 

   The parameters are as specified in Section 2. 

 
 
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   The SMIMECapabilities attribute value indicates support for SHA-384 
   in a SEQUENCE with the capabilityID field containing the object 
   identifier id-sha384 with absent parameters.  The DER encoding for 
   this SMIMECapability value is: 

      id-sha512: 30 0b 06 09 60 86 48 01 65 03 04 02 03 

3. Signature Algorithms 

   This section specifies the conventions employed by CMS 
   implementations that support DSA, RSA, and ECDSA with SHA2 
   algorithms. 

   Signature algorithm identifiers are located in the SignerInfo 
   signatureAlgorithm field of SignedData.  Also, signature algorithm 
   identifiers are located in the SignerInfo signatureAlgorithm field of 
   countersignature attributes. 

   Signature values are located in the SignerInfo signature field of 
   SignedData.  Also, signature values are located in the SignerInfo 
   signature field of countersignature attributes. 

3.1. DSA 

   [RFC3370] section 3.1 specifies the conventions for DSA with SHA-1 
   public key algorithm identifiers, parameters, public keys, and 
   signature values. DSA with SHA2 algorithms uses the same conventions 
   for these public key algorithm identifiers, parameters, public keys, 
   and signature values.  DSA MAY be used with SHA-224 and SHA-256.  The 
   object identifiers are taken from [ECCADD]. 

   DSA has not been specified with SHA-384 and SHA-512.  SHA-384 and 
   SHA-512 are not supported because the maximum bit length of p 
   (specified as L) is 3072 for DSA.  For consistent cryptographic 
   strength, SHA-384 would be used with DSA where L is 7680, and SHA-512 
   would be used with DSA where L is 15360. 

   The algorithm identifier for DSA with SHA-224 signature values is: 

     id-dsa-with-sha224 OBJECT IDENTIFIER ::=  { 
       joint-iso-ccitt(2) country(16) us(840) organization(1) gov(101) 
       csor(3) algorithms(4) id-dsa-with-sha2(3) 1 } 

 
 
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   The algorithm identifier for DSA with SHA-256 signature values is: 

     id-dsa-with-sha256 OBJECT IDENTIFIER ::=  { 
       joint-iso-ccitt(2) country(16) us(840) organization(1) gov(101) 
       csor(3) algorithms(4) id-dsa-with-sha2(3) 2 } 

   When either of these algorithm identifiers is used, the 
   AlgorithmIdentifier parameters field MUST be absent. 

   The SMIMECapabilities attribute value indicates support for one of 
   the DSA signature algorithms in a SEQUENCE with the capabilityID 
   field containing the object identifier id-dsa-with-sha* (where * is 
   224 or 256) with absent parameters.  The DER encoding for these 
   SMIMECapability values are: 

      id-dsa-with-sha224: 30 0b 06 09 60 86 48 01 65 03 04 03 01 

      id-dsa-with-sha256: 30 0b 06 09 60 86 48 01 65 03 04 03 02 

3.2. RSA 

   [RFC3370] section 3.2 specifies the conventions for RSA with SHA-1 
   (RSASSA-PKCS1-v1_5) public key algorithm identifiers, parameters, 
   public keys, and signature values. RSA with SHA2 algorithms uses the 
   same conventions for these public key algorithm identifiers, 
   parameters, public keys, and signature values.  RSA (RSASSA-PKCS1-
   v1_5) [RFC3447] MAY be used with SHA-224, SHA-256, SHA-384, or SHA-
   512.  The object identifiers are taken from [RFC4055]. 

   The object identifier for RSA with SHA-224 signature values is: 

     sha224WithRSAEncryption OBJECT IDENTIFIER ::= { iso(1) 
       member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 14 } 

   The object identifier for RSA with SHA-256 signature values is: 

     sha256WithRSAEncryption  OBJECT IDENTIFIER  ::=  { iso(1) 
       member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 11 } 

   The object identifier for RSA with SHA-384 signature values is: 

     sha384WithRSAEncryption  OBJECT IDENTIFIER  ::=  { iso(1) 
       member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 12 } 

 
 
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   The object identifier for RSA with SHA-512 signature values is: 

     sha512WithRSAEncryption  OBJECT IDENTIFIER  ::=  { iso(1) 
       member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 13 } 

   When any of these four object identifiers appears within an 
   AlgorithmIdentifier, the parameters MUST be NULL.  Implementations 
   MUST accept the parameters being absent as well as present. 

   The SMIMECapabilities attribute value indicates support for one of 
   the DSA signature algorithms in a SEQUENCE with the capabilityID 
   field containing the object identifier sha*WithRSAEncryption (where * 
   is 224, 256, 384, or 512) with NULL parameters.  The DER encoding for 
   these SMIMECapability values are: 

      sha224WithRSAEncryption: 30 0d 06 09 2a 86 48 86 f7 0d 01 01 0e 
                               05 00 

      sha256WithRSAEncryption: 30 0d 06 09 2a 86 48 86 f7 0d 01 01 0b 
                               05 00 

      sha384WithRSAEncryption: 30 0d 06 09 2a 86 48 86 f7 0d 01 01 Oc 
                               05 00 

      sha512WithRSAEncryption: 30 0d 06 09 2a 86 48 86 f7 0d 01 01 0d 
                               05 00 

3.3. ECDSA 

   [RFCTBD2] section 2.1 specifies the conventions for ECDSA with SHA-1 
   public key algorithm identifiers, parameters, public keys, and 
   signature values. ECDSA with SHA2 algorithms uses the same 
   conventions for these public key algorithm identifiers, parameters, 
   public keys, and signature values, except that the digestAlgorithm 
   MUST include the corresponding message digest algorithm identifier, 
   and not the SHA-1 object identifier.  ECDSA MAY be used with SHA-224, 
   SHA-256, SHA-384, or SHA-512.  The object identifiers are taken from 
   [ECCADD]. 

   The algorithm identifier for ECDSA with SHA-224 signature values is: 

     ecdsa-with-SHA224 OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
       us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 1 } 

 
 
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   The algorithm identifier for ECDSA with SHA-256 signature values is: 

     ecdsa-with-SHA256 OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
       us(840)ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 2 } 

   The algorithm identifier for ECDSA with SHA-384 signature values is: 

     ecdsa-with-SHA384 OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
       us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 3 } 

   The algorithm identifier for ECDSA with SHA-512 signature values is: 

     ecdsa-with-SHA512 OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
       us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 4 } 

   When any of these four object identifiers appears within an 
   AlgorithmIdentifier, the parameters field MUST be absent.  That is, 
   the AlgorithmIdentifier SHALL be a SEQUENCE of one component: the OID 
   ecdsa-with-SHA224, ecdsa-with-SHA256,  
   ecdsa-with-SHA384 or ecdsa-with-SHA512. 

   The SMIMECapabilities attribute value indicates support for one of 
   the ECDSA signature algorithms in a SEQUENCE with the capabilityID 
   field containing the object identifier ecdsa-with-SHA1* (where * is 
   224, 256, 384, or 512) with absent parameters.  The DER encoding for 
   these SMIMECapability values are: 

      ecdsa-with-SHA224: 30 0a 06 08 2a 86 48 ce 3d 04 03 01 

      ecdsa-with-SHA256: 30 0a 06 08 2a 86 48 ce 3d 04 03 02 

      ecdsa-with-SHA384: 30 0a 06 08 2a 86 48 ce 3d 04 03 03 

      ecdsa-with-SHA512: 30 0a 06 08 2a 86 48 ce 3d 04 03 04 

4. Security Considerations 

   The security considerations in [RFC3370], [RFC3874], [RFC4055], 
   [RFCTBD2], and [ECCADD] apply. No new security considerations are 
   introduced as a result of this specification. 

5. IANA Considerations 

   None: All identifiers are already registered.  Please remove this 
   section prior to publication as an RFC. 

 
 
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6. References 

6.1. Normative References 

   [ECCADD]    Dang, S., Santesson, S., Moriarty, K., and Brown, 
               "Internet X.509 Public Key Infrastructure: Additional 
               Algorithms and Identifiers for DSA and ECDSA",  draft-
               ietf-pkix-sha2-dsa-ecdsa-05.txt (work-in-progress). 

   [DSS]       National Institute of Standards and Technology (NIST), 
               FIPS Publication 186-3: Digital Signature Standard, 
               (draft) November 2008. 

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

   [RFC3370]   Housley, R., "Cryptographic Message Syntax (CMS) 
               Algorithms", RFC 3370, August 2002. 

   [RFC3447]   Kaliski, B. and J. Jonsson "Public-Key Cryptography 
               Standards (PKCS) #1: RSA Cryptography Specifications 
               Version 2.1", RFC 3447, February 2003. 

   [RFC3852]   Housley, R., "The Cryptographic Message Syntax (CMS)", 
               RFC 3852. July 2004. 

   [RFC3874]   Housley, R., "A 224-bit One Way Hash Function: SHA-224", 
               RFC 3874. September 2004. 

   [RFC4055]   Schaad, J., Kaliski, B., and R. Housley, "Additional 
               Algorithms and Identifiers for RSA Cryptography for use 
               in the Internet Public Key Infrastructure Certificate and 
               Certificate Revocation List (CRL) Profile", RFC 4055. 
               June 2005. 

   [RFCTBD1]   Ramsdell, B., and S. Turner, "S/MIME Version 3.2 Message 
               Specification", draft-ietf-smime-3851bis-08.txt, work-in-
               progress. 

   //* RFC EDITOR: Note replace the above TBD1 with the RFC # for draft-
   ietf-smime-3851bis-08.txt. *// 

 
 
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   [RFCTBD2]   Turner, S., and D. Brown, "Use of Elliptic Curve 
               Cryptography (ECC) Algorithms in Cryptographic Message 
               Syntax (CMS)", draft-ietf-smime-3278bis-05, work-in-
               progress. 

   //* RFC EDITOR: Note replace the above TBD2 with the RFC # for draft-
   ietf-smime-3278bis-05.txt. *// 

   [SHS]       National Institute of Standards and Technology (NIST), 
               FIPS Publication 180-3: Secure Hash Standard, October 
               2008. 

6.2. Informative References 

   [RFC4231]   Nystrom, A. "Identifiers and Test Vectors for HMAC-SHA-
               224, HMAC-SHA-256, HMAC-SHA-384, and HMAC-SHA-512", 
               RFC4231. December 2005. 

   [RFC4634]   Eastlake, D., and T. Hansen, "US Secure Hash Algorithms 
               (SHA and HMAC-SHA)", RFC 4634, July 2006. 

Author's Addresses 

   Sean Turner 

   IECA, Inc. 
   3057 Nutley Street, Suite 106 
   Fairfax, VA 22031 
   USA 

   EMail: turners@ieca.com 

 
 
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