Suite B in Secure/Multipurpose Internet Mail Extensions (S/MIME)
RFC 6318

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Internet Engineering Task Force (IETF)                        R. Housley
Request for Comments: 6318                                Vigil Security
Obsoletes: 5008                                               J. Solinas
Category: Informational                         National Security Agency
ISSN: 2070-1721                                                June 2011

    Suite B in Secure/Multipurpose Internet Mail Extensions (S/MIME)

Abstract

   This document specifies the conventions for using the United States
   National Security Agency's Suite B algorithms in Secure/Multipurpose
   Internet Mail Extensions (S/MIME) as specified in RFC 5751.  This
   document obsoletes RFC 5008.

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.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6318.

Housley & Solinas             Informational                     [Page 1]
RFC 6318                    Suite B in S/MIME                  June 2011

Copyright Notice

   Copyright (c) 2011 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
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   include Simplified BSD License text as described in Section 4.e of
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   described in the Simplified BSD License.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Table of Contents

   1. Introduction ....................................................3
      1.1. Terminology ................................................4
      1.2. ASN.1 ......................................................4
      1.3. Suite B Security Levels ....................................4
   2. SHA-256 and SHA-384 Message Digest Algorithms ...................5
   3. ECDSA Signature Algorithm .......................................6
   4. Key Management ..................................................7
      4.1. ECDH Key Agreement Algorithm ...............................7
      4.2. AES Key Wrap ...............................................8
      4.3. Key Derivation Functions ...................................9
   5. AES CBC Content Encryption .....................................11
   6. Security Considerations ........................................12
   7. References .....................................................13
      7.1. Normative References ......................................13
      7.2. Informative References ....................................14

Housley & Solinas             Informational                     [Page 2]
RFC 6318                    Suite B in S/MIME                  June 2011

1.  Introduction

   The Fact Sheet on National Security Agency (NSA) Suite B Cryptography
   [NSA] states:

      A Cryptographic Interoperability Strategy (CIS) was developed to
      find ways to increase assured rapid sharing of information both
      within the U.S. and between the U.S. and her partners through the
      use of a common suite of public standards, protocols, algorithms
      and modes referred to as the "Secure Sharing Suite" or S.3.  The
      implementation of CIS will facilitate the development of a broader
      range of secure cryptographic products which will be available to
      a wide customer base.  The use of selected public cryptographic
      standards and protocols and Suite B is the core of CIS.

      In 2005, NSA announced Suite B Cryptography which built upon the