ChaCha20 and Poly1305 for IETF Protocols
RFC 7539
Document | Type |
RFC - Informational
(May 2015; Errata)
Obsoleted by RFC 8439
|
|
---|---|---|---|
Authors | Yoav Nir , Adam Langley | ||
Last updated | 2020-01-21 | ||
Replaces | draft-nir-cfrg-chacha20-poly1305 | ||
Stream | IRTF | ||
Formats | plain text html pdf htmlized with errata bibtex | ||
IETF conflict review | conflict-review-irtf-cfrg-chacha20-poly1305 | ||
Stream | IRTF state | Published RFC | |
Consensus Boilerplate | Yes | ||
Document shepherd | Alexey Melnikov | ||
IESG | IESG state | RFC 7539 (Informational) | |
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) | ||
IANA | IANA review state | Version Changed - Review Needed | |
IANA action state | RFC-Ed-Ack |
Internet Research Task Force (IRTF) Y. Nir Request for Comments: 7539 Check Point Category: Informational A. Langley ISSN: 2070-1721 Google, Inc. May 2015 ChaCha20 and Poly1305 for IETF Protocols Abstract This document defines the ChaCha20 stream cipher as well as the use of the Poly1305 authenticator, both as stand-alone algorithms and as a "combined mode", or Authenticated Encryption with Associated Data (AEAD) algorithm. This document does not introduce any new crypto, but is meant to serve as a stable reference and an implementation guide. It is a product of the Crypto Forum Research Group (CFRG). 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 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/rfc7539. Copyright Notice Copyright (c) 2015 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. Nir & Langley Informational [Page 1] RFC 7539 ChaCha20 & Poly1305 May 2015 Table of Contents 1. Introduction ....................................................3 1.1. Conventions Used in This Document ..........................4 2. The Algorithms ..................................................4 2.1. The ChaCha Quarter Round ...................................4 2.1.1. Test Vector for the ChaCha Quarter Round ............5 2.2. A Quarter Round on the ChaCha State ........................5 2.2.1. Test Vector for the Quarter Round on the ChaCha State ........................................6 2.3. The ChaCha20 Block Function ................................6 2.3.1. The ChaCha20 Block Function in Pseudocode ...........8 2.3.2. Test Vector for the ChaCha20 Block Function .........9 2.4. The ChaCha20 Encryption Algorithm .........................10 2.4.1. The ChaCha20 Encryption Algorithm in Pseudocode ....11 2.4.2. Example and Test Vector for the ChaCha20 Cipher ....11 2.5. The Poly1305 Algorithm ....................................13 2.5.1. The Poly1305 Algorithms in Pseudocode ..............15 2.5.2. Poly1305 Example and Test Vector ...................15 2.6. Generating the Poly1305 Key Using ChaCha20 ................17 2.6.1. Poly1305 Key Generation in Pseudocode ..............18 2.6.2. Poly1305 Key Generation Test Vector ................18 2.7. A Pseudorandom Function for Crypto Suites based on ChaCha/Poly1305 ...........................................18 2.8. AEAD Construction .........................................19 2.8.1. Pseudocode for the AEAD Construction ...............21 2.8.2. Example and Test Vector for AEAD_CHACHA20_POLY1305 .............................22 3. Implementation Advice ..........................................24 4. Security Considerations ........................................24 5. IANA Considerations ............................................26 6. References .....................................................26 6.1. Normative References ......................................26 6.2. Informative References ....................................26 Appendix A. Additional Test Vectors ...............................29 A.1. The ChaCha20 Block Functions ...............................29 A.2. ChaCha20 Encryption ........................................32 A.3. Poly1305 Message Authentication Code .......................34 A.4. Poly1305 Key Generation Using ChaCha20 .....................40 A.5. ChaCha20-Poly1305 AEAD Decryption ..........................41Show full document text