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A 224-bit One-way Hash Function: SHA-224 (RFC3874)

IP.com Disclosure Number: IPCOM000031091D
Original Publication Date: 2004-Sep-01
Included in the Prior Art Database: 2004-Sep-10
Document File: 7 page(s) / 12K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

R. Housley: AUTHOR

Abstract

This document specifies a 224-bit one-way hash function, called SHA-224. SHA-224 is based on SHA-256, but it uses a different initial value and the result is truncated to 224 bits.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 24% of the total text.

Network Working Group                                         R. Housley

Request for Comments: 3874                                Vigil Security

Category: Informational                                   September 2004

                A 224-bit One-way Hash Function: SHA-224

Status of this Memo

   This memo provides information for the Internet community.  It does

   not specify an Internet standard of any kind.  Distribution of this

   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2004).

Abstract

   This document specifies a 224-bit one-way hash function, called

   SHA-224.  SHA-224 is based on SHA-256, but it uses a different

   initial value and the result is truncated to 224 bits.

1.  Introduction

   This document specifies a 224-bit one-way hash function, called

   SHA-224.  The National Institute of Standards and Technology (NIST)

   announced the FIPS 180-2 Change Notice on February 28, 2004 which

   specifies the SHA-224 one-way hash function.  One-way hash functions

   are also known as message digests.  SHA-224 is based on SHA-256, the

   256-bit one-way hash function already specified by NIST [SHA2].

   Computation of a SHA-224 hash value is two steps.  First, the SHA-256

   hash value is computed, except that a different initial value is

   used.  Second, the resulting 256-bit hash value is truncated to 224

   bits.

   NIST is developing guidance on cryptographic key management, and NIST

   recently published a draft for comment [NISTGUIDE].  Five security

   levels are discussed in the guidance: 80, 112, 128, 192, and 256 bits

   of security.  One-way hash functions are available for all of these

   levels except one.  SHA-224 fills this void.  SHA-224 is a one-way

   hash function that provides 112 bits of security, which is the

   generally accepted strength of Triple-DES [3DES].

   This document makes the SHA-224 one-way hash function specification

   available to the Internet community, and it publishes the object

   identifiers for use in ASN.1-based protocols.

Housley                      Informational                      [Page 1]

RFC 3874        A 224-bit One-way Hash Function: SHA-224  September 2004

1.1.  Usage Considerations

   Since SHA-224 is based on SHA-256, roughly the same amount of effort

   is consumed to compute a SHA-224 or a SHA-256 digest message digest

   value.  Even though SHA-224 and SHA-256 have roughly equivalent

   computational complexity, SHA-224 is an appropriate choice for a

   one-way hash function that provides 112 bits of security.  The use of

   a different initial value ensures that a truncated SHA-256 message

   digest value cannot be mistaken for a SHA-224 message digest value

   computed on the same data.

  ...