SHA256

1. 15th October 2002. Updated to remove the use of the 'standard' fixed width integer types.
2. 30th November 2002. Updated to add SHA1, to improve performance of SH256 and to remove an error in SHA384 and SHA512 for data digests larger than 2^29 bytes (reported by Jan Krhovjak).
3. 26th August 2003. Updated to add more functions.
4. 26th January 2004. Added SHA224 and support for bit level hashing.
5. 7th June 2004. Reverted to a version that handles Microsoft 64-bit types in VC++ version 6
6. 23rd February 2005. Change to allow use on machines with no 64-bit integer support (suggested by Peter Gutmann)
7. 26th August 2005 - Minor update to bring code in line with types used in my AES code.
8. 22nd November 2006 - Minor update for type definitions (brg_types.h)
9. 7th January 2007 - Minor update to fix error in shasum.c (reported by several people).

This code implements the US NIST Secure Hash Algorithms in C. Both SHA1 and SHA2 are provided. Code is also provided for HMAC and for key derivation as described in RFC2898 and PKCS#5.

The performance of this code in machine cycles per data byte on Intel and AMD systems for different hash data lengths is:

Data Length	1	10	100	1,000	10,000	100,000
AMD64 (64 bit mode)
SHA1	672	70.1	13.07	9.79	9.4	9.7
SHA224	1436	145.3	27.9	21.1	20.4	20.4
SHA256	1483	149.9	28.4	21.1	20.4	20.4
SHA384	1864	187.9	19.9	13.9	13.5	13.4
SHA512	1939	195.6	20.6	14.0	13.5	13.4
AMD64 (32 bit mode)
SHA1	764	77.7	14.8	10.9	10.5	10.7
SHA224	1608	161.9	31.3	23.8	23.2	23.6
SHA256	1628	163.9	31.8	24.1	23.4	23.3
SHA384	7246	725.4	73.7	54.2	52.9	52.6
SHA512	7487	749.8	75.8	54.4	52.9	52.5
Intel P3
SHA1	1401	128.1	22.9	20.5	20.2	17.2
SHA224	2865	294.1	59.4	42.7	41.4	41.0
SHA256	2993	292.5	55.8	42.7	41.5	41.0
SHA384	23253	2380.1	241.9	177.9	174.5	173.1
SHA512	23653	2433.7	239.2	177.5	174.7	172.8

SHA1, SHA2, HMAC and Key Derivation in C