Update to the Cryptographic Message Syntax (CMS) Algorithm Identifier Protection Attribute

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Table of Contents

1. Introduction

This document corrects a mistake in [RFC6211]. It corrects an error in definition of the id-aa-CMSAlgorithmProtection ASN.1 object identifier.¶

The IANA registry entry for this ASN.1 object identifier does not need to be updated; it has always been correct.¶

The authors are aware of two implementations of RFC 6211, but they did not interoperate because one used the ASN.1 object identifier from RFC 6211 and the other used the ASN.1 object identifier from the IANA registry.¶

The mistakes were reported in [Err9144] and [Err9145].¶

This update to RFC 6211 will hopefully resolve future interoperability troubles.¶

2. Update to Section 2 of RFC 6211

OLD:¶

   The following object identifier identifies the algorithm protection
   attribute:

       id-aa-CMSAlgorithmProtection OBJECT IDENTIFIER ::= { iso(1)
            member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9) 52 }

NEW:¶

   The following object identifier identifies the algorithm protection
   attribute:

       id-aa-CMSAlgorithmProtection OBJECT IDENTIFIER ::= { iso(1)
            member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
            smime(16) aa(2) 52 }

3. Update to Appendix A of RFC 6211

OLD:¶

     id-aa-cmsAlgorithmProtect OBJECT IDENTIFIER ::= {
        iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
        pkcs9(9) 52 }

NEW:¶

     id-aa-cmsAlgorithmProtect OBJECT IDENTIFIER ::= {
        iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
        pkcs9(9) smime(16) aa(2) 52 }

4. IANA Considerations

No IANA registr updates are needed. The IANA registry is correct.¶

5. Security Considerations

The CMS attribute specified in [RFC6211] is designed to address the security issue of algorithm substitutions. That is, the originator uses one algorithm, an attacker modifies the message, and then the validator uses a different algorithm. The specified protection is not successful unless all implementers use the same ASN.1 object identifier for the attribute.¶

6. References

Acknowledgments

Thanks to Paul Timmel for being the first person to spot the error in [RFC6211].¶

Authors' Addresses