US Secure Hash Algorithms (SHA and SHA-based HMAC and HKDF)
RFC 6234
| Document | Type |
RFC - Informational
(May 2011; Errata)
Obsoletes RFC 4634
Updates RFC 3174
Was draft-eastlake-sha2b (individual in gen area)
|
|
|---|---|---|---|
| Last updated | 2017-11-07 | ||
| Stream | IETF | ||
| Formats | plain text html pdf htmlized with errata bibtex | ||
| Reviews | |||
| Stream | WG state | (None) | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 6234 (Informational) | |
| Consensus Boilerplate | Unknown | ||
| Telechat date | |||
| Responsible AD | Russ Housley | ||
| Send notices to | (None) | ||
Internet Engineering Task Force (IETF) D. Eastlake 3rd
Request for Comments: 6234 Huawei
Obsoletes: 4634 T. Hansen
Updates: 3174 AT&T Labs
Category: Informational May 2011
ISSN: 2070-1721
US Secure Hash Algorithms
(SHA and SHA-based HMAC and HKDF)
Abstract
The United States of America has adopted a suite of Secure Hash
Algorithms (SHAs), including four beyond SHA-1, as part of a Federal
Information Processing Standard (FIPS), namely SHA-224, SHA-256,
SHA-384, and SHA-512. This document makes open source code
performing these SHA hash functions conveniently available to the
Internet community. The sample code supports input strings of
arbitrary bit length. Much of the text herein was adapted by the
authors from FIPS 180-2.
This document replaces RFC 4634, fixing errata and adding code for an
HMAC-based extract-and-expand Key Derivation Function, HKDF (RFC
5869). As with RFC 4634, code to perform SHA-based Hashed Message
Authentication Codes (HMACs) is also included.
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/rfc6234.
Eastlake & Hansen Informational [Page 1]
RFC 6234 SHAs, HMAC-SHAs, and HKDF May 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
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.
Eastlake & Hansen Informational [Page 2]
RFC 6234 SHAs, HMAC-SHAs, and HKDF May 2011
Table of Contents
1. Overview of Contents ............................................4
2. Notation for Bit Strings and Integers ...........................5
3. Operations on Words .............................................6
4. Message Padding and Parsing .....................................8
4.1. SHA-224 and SHA-256 ........................................8
4.2. SHA-384 and SHA-512 ........................................9
5. Functions and Constants Used ...................................10
5.1. SHA-224 and SHA-256 .......................................10
5.2. SHA-384 and SHA-512 .......................................11
6. Computing the Message Digest ...................................12
6.1. SHA-224 and SHA-256 Initialization ........................12
6.2. SHA-224 and SHA-256 Processing ............................13
6.3. SHA-384 and SHA-512 Initialization ........................14
6.4. SHA-384 and SHA-512 Processing ............................15
7. HKDF- and SHA-Based HMACs ......................................17
7.1. SHA-Based HMACs ...........................................17
7.2. HKDF ......................................................17
8. C Code for SHAs, HMAC, and HKDF ................................17
8.1. The Header Files ..........................................21
8.1.1. The .h file ........................................21
8.1.2. stdint-example.h ...................................29
8.1.3. sha-private.h ......................................29
8.2. The SHA Code ..............................................30
8.2.1. sha1.c .............................................30
8.2.2. sha224-256.c .......................................39
8.2.3. sha384-512.c .......................................51
8.2.4. usha.c .............................................73
8.3. The HMAC Code .............................................79
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