ChaCha20 and Poly1305 based Cipher Suites for TLS
draft-agl-tls-chacha20poly1305-03

The information below is for an old version of the document
Document Type Active Internet-Draft (individual)
Authors Adam Langley  , Wan-Teh Chang 
Last updated 2013-11-08
Stream (None)
Intended RFC status (None)
Formats pdf htmlized (tools) htmlized bibtex
Stream Stream state (No stream defined)
Consensus Boilerplate Unknown
RFC Editor Note (None)
IESG IESG state I-D Exists
Telechat date
Responsible AD (None)
Send notices to (None)
Network Working Group                                         A. Langley
Internet-Draft                                                  W. Chang
Expires: May 5, 2014                                          Google Inc
                                                                Nov 2013

           ChaCha20 and Poly1305 based Cipher Suites for TLS
                   draft-agl-tls-chacha20poly1305-03

Abstract

   This memo describes the use of the ChaCha20 cipher with a Poly1305
   authenticator in Transport Layer Security (TLS).

Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 5, 2014.

Copyright Notice

   Copyright (c) 2013 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
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Langley & Chang            Expires May 5, 2014                  [Page 1]
Internet-Draft          ChaCha20Poly1305 for TLS                Nov 2013

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Requirements Notation  . . . . . . . . . . . . . . . . . . . .  4
   3.  ChaCha20 . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
   4.  Poly1305 . . . . . . . . . . . . . . . . . . . . . . . . . . .  7
   5.  AEAD construction  . . . . . . . . . . . . . . . . . . . . . .  8
   6.  Cipher suites  . . . . . . . . . . . . . . . . . . . . . . . . 10
   7.  Test vectors . . . . . . . . . . . . . . . . . . . . . . . . . 11
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 14
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 15
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
     10.1.  Normative References  . . . . . . . . . . . . . . . . . . 16
     10.2.  Informative References  . . . . . . . . . . . . . . . . . 16
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17

Langley & Chang            Expires May 5, 2014                  [Page 2]
Internet-Draft          ChaCha20Poly1305 for TLS                Nov 2013

1.  Introduction

   Existing TLS [RFC5246] cipher suites either suffer from cryptographic
   weaknesses (RC4), major implementation pitfalls (CBC mode block
   ciphers) or are difficult to efficiently and securely implement in
   software (AES-GCM).  In order to improve the state of software TLS
   implementations, this memo specifies cipher suites that can be fast
   and secure when implemented in software without sacrificing key
   agility.

Langley & Chang            Expires May 5, 2014                  [Page 3]
Internet-Draft          ChaCha20Poly1305 for TLS                Nov 2013

2.  Requirements Notation

   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 RFC 2119 [RFC2119].

Langley & Chang            Expires May 5, 2014                  [Page 4]
Internet-Draft          ChaCha20Poly1305 for TLS                Nov 2013

3.  ChaCha20

   ChaCha20 [chacha] is a stream cipher developed by D. J. Bernstein.
   It is a refinement of Salsa20 and was used as the core of the SHA-3
   finalist, BLAKE.

   ChaCha20 maps 16, 32-bit input words to 16, 32-bit output words.  By
   convention, 8 of the input words consist of a 256-bit key, 4 are
   constants and the remaining four are an nonce and block counter.  The
   output words are converted to bytes and XORed with the plaintext to
   produce ciphertext.  In order to generate sufficient output bytes to
   XOR with the whole plaintext, the block counter is incremented and
   ChaCha20 is run again, as many times as needed, for up to 2^70 bytes
Show full document text