AES-GCM-SIV: Nonce Misuse-Resistant Authenticated Encryption
RFC 8452

Document Type RFC - Informational (April 2019; No errata)
Last updated 2019-04-17
Replaces draft-gueron-gcmsiv
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Internet Research Task Force (IRTF)                            S. Gueron
Request for Comments: 8452                University of Haifa and Amazon
Category: Informational                                       A. Langley
ISSN: 2070-1721                                               Google LLC
                                                              Y. Lindell
                                    Bar-Ilan University and Unbound Tech
                                                              April 2019

      AES-GCM-SIV: Nonce Misuse-Resistant Authenticated Encryption

Abstract

   This memo specifies two authenticated encryption algorithms that are
   nonce misuse resistant -- that is, they do not fail catastrophically
   if a nonce is repeated.

   This document is the product of the Crypto Forum Research Group.

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 Research Task Force
   (IRTF).  The IRTF publishes the results of Internet-related research
   and development activities.  These results might not be suitable for
   deployment.  This RFC represents the consensus of the Crypto Forum
   Research Group of the Internet Research Task Force (IRTF).  Documents
   approved for publication by the IRSG are not candidates for any level
   of Internet Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8452.

Copyright Notice

   Copyright (c) 2019 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
   (https://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.

Gueron, et al.                Informational                     [Page 1]
RFC 8452                       AES-GCM-SIV                    April 2019

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  POLYVAL . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Encryption  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Decryption  . . . . . . . . . . . . . . . . . . . . . . . . .   7
   6.  AEADs . . . . . . . . . . . . . . . . . . . . . . . . . . . .  10
   7.  Field Operation Examples  . . . . . . . . . . . . . . . . . .  10
   8.  Worked Example  . . . . . . . . . . . . . . . . . . . . . . .  10
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  14
     11.2.  Informative References . . . . . . . . . . . . . . . . .  15
   Appendix A.  The Relationship between POLYVAL and GHASH . . . . .  17
   Appendix B.  Additional Comparisons with AES-GCM  . . . . . . . .  19
   Appendix C.  Test Vectors . . . . . . . . . . . . . . . . . . . .  20
     C.1.  AEAD_AES_128_GCM_SIV  . . . . . . . . . . . . . . . . . .  20
     C.2.  AEAD_AES_256_GCM_SIV  . . . . . . . . . . . . . . . . . .  30
     C.3.  Counter Wrap Tests  . . . . . . . . . . . . . . . . . . .  41
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  42
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  42

1.  Introduction

   The concept of Authenticated Encryption with Additional Data (AEAD)
   [RFC5116] couples confidentiality and integrity in a single
   operation, avoiding the risks of the previously common practice of
   using ad hoc constructions of block-cipher and hash primitives.  The
   most popular AEAD, AES-GCM [GCM], is seeing widespread use due to its
   attractive performance.

   However, some AEADs (including AES-GCM) suffer catastrophic failures
   of confidentiality and/or integrity when two distinct messages are
   encrypted with the same key and nonce.  While the requirements for
   AEADs specify that the pair of (key, nonce) shall only ever be used
   once, and thus prohibit this, this is a worry in practice.

   Nonce misuse-resistant AEADs do not suffer from this problem.  For
   this class of AEADs, encrypting two messages with the same nonce only
   discloses whether the messages were equal or not.  This is the
   minimum amount of information that a deterministic algorithm can leak
   in this situation.

   This memo specifies two nonce misuse-resistant AEADs:
   AEAD_AES_128_GCM_SIV and AEAD_AES_256_GCM_SIV.  These AEADs are
   designed to be able to take advantage of existing hardware support
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