pgpsha.c

著名的加密软件的应用于电子邮件中

/*
* pgpSHA.c - NIST Secure Hash Algorithm, FIPS PUB 180 and 180.1.
* The algorithm is by spook(s) unknown at the U.S. National Security Agency.
*
* Written 2 September 1992, Peter C. Gutmann.
* This implementation placed in the public domain.
*
* Modified 1 June 1993, Colin Plumb.
* Modified for the new SHS based on Peter Gutmann's work,
* 18 July 1994, Colin Plumb.
*
* Renamed to SHA and comments updated a bit 1 November 1995, Colin Plumb.
* These modifications placed in the public domain.
* Hacked on some more for PGP 3, December 1995, Colin Plumb.
* You probably don't *want* these modifications.
*
* Comments to [e-mail]
*
* $Id: pgpSHA.c,v 1.1.2.1 1997/05/19 00:59:57 hal Exp $
*/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <string.h>

#include "pgpHash.h"
#include "pgpSHA.h"
#include "pgpUsuals.h"

/*
* Define to 1 for FIPS 180.1 version (with extra rotate in prescheduling),
* 0 for FIPS 180 version (with the mysterious "weakness" that the NSA
* isn't talking about).
*/
#define SHA_VERSION 1

#define SHA_BLOCKBYTES 64
#define SHA_BLOCKWORDS 16

#define SHA_HASHBYTES 20
#define SHA_HASHWORDS 5

struct SHAContext {
 word32 key[SHA_BLOCKWORDS];
 word32 iv[SHA_HASHWORDS];
#if HAVE64
	word64 bytes;
#else
	word32 bytesHi, bytesLo;
#endif
};

/*
* Shuffle the bytes into big-endian order within words, as per the
* SHA spec.
*/
static void
shaByteSwap(word32 *dest, byte const *src, unsigned words)
	{
		do {
			*dest++ = (word32)((unsigned)src[0] << 8 | src[1]) << 16 |
			((unsigned)src[2] << 8 | src[3]);
			src += 4;
		} while (--words);
}

/* Initialize the SHA values */

static void
shaInit(void *priv)
	{
		struct SHAContext *ctx = (struct SHAContext *)priv;

		/* Set the h-vars to their initial values */
		ctx->iv[0] = 0x67452301;
		ctx->iv[1] = 0xEFCDAB89;
		ctx->iv[2] = 0x98BADCFE;
		ctx->iv[3] = 0x10325476;
		ctx->iv[4] = 0xC3D2E1F0;

		/* Initialise bit count */
#ifdef HAVE64
		ctx->bytes = 0;
	#else
		ctx->bytesHi = 0;
		ctx->bytesLo = 0;
	#endif
	}

/*
* The SHA f()-functions. The f1 and f3 functions can be optimized to
* save one boolean operation each - thanks to Rich Schroeppel,
* [e-mail] for discovering this.
* The f3 function can be modified to use an addition to combine the
* two halves rather than OR, allowing more opportunity for using
* associativity in optimization. (Colin Plumb)
*
* Note that it may be necessary to add parentheses to these macros
* if they are to be called with expressions as arguments.
*/
/* f1 is a bit-select function. If (x) then y else z */
/*#define f1(x,y,z) ( (x & y) | (~x & z) )  // Rounds 0-19 */
#define f1(x,y,z) ( z ^ (x & (y ^ z) ) )  /* Rounds 0-19 */
#define f2(x,y,z) ( x ^ y ^ z )   /* Rounds 20-39 */
/* f3 is a majority function */
/*#define f3(x,y,z) ( (x & y) | (y & z) | (z & x) ) // Rounds 40-59 */
/*#define f3(x,y,z) ( (x & y) | (z & (x | y) ) ) // Rounds 40-59 */
#define f3(x,y,z) ( (x & y) + (z & (x ^ y) ) ) /* Rounds 40-59 */
#define f4(x,y,z) ( x ^ y ^ z )   /* Rounds 60-79 */

/* The SHA Mysterious Constants. */
#define K2 0x5A827999L /* Rounds 0-19 - floor(sqrt(2) * 2^30) */
#define K3 0x6ED9EBA1L /* Rounds 20-39 - floor(sqrt(3) * 2^30) */
#define K5 0x8F1BBCDCL /* Rounds 40-59 - floor(sqrt(5) * 2^30) */
#define K10 0xCA62C1D6L /* Rounds 60-79 - floor(sqrt(10) * 2^30) */
/* I wonder why not use K7=0xA953FD4E, K11=0xD443949F or K13=0xE6C15A23 */

/* 32-bit rotate left - kludged with shifts */

#define ROTL(n,X) ( (X << n) | (X >> (32-n)) )

/*
* The initial expanding function
*
* The hash function is defined over an 80-word expanded input array W,
* where the first 16 are copies of the input data, and the remaining 64
* are defined by W[i] = W[i-16] ^ W[i-14] ^ W[i-8] ^ W[i-3]. This
* implementation generates these values on the fly in a circular buffer.
*
* The new "corrected" FIPS 180.1 added a 1-bit left rotate to this
* computation of W[i].
*
* The expandx() version doesn't write the result back, which can be
* used for the last three rounds since those outputs are never used.
*/

#if SHA_VERSION /* FIPS 180.1 */
#define expandx(W,i) (t = W[i&15] ^ W[(i-14)&15] ^ W[(i-8)&15] ^ W[(i-3)&15], \
ROTL(1, t))
#define expand(W,i) (W[i&15] = expandx(W,i))
#else /* Old FIPS 180 */
#define expandx(W,i) (W[i&15] ^ W[(i-14)&15] ^ W[(i-8)&15] ^ W[(i-3)&15])
#define expand(W,i) (W[i&15] ^= W[(i-14)&15] ^ W[(i-8)&15] ^ W[(i-3)&15])
#endif

/*
* The prototype SHA sub-round
*
* The fundamental sub-round is
* a' = e + ROTL(5,a) + f(b, c, d) + k + data;
* b' = a;
* c' = ROTL(30,b);
* d' = c;
* e' = d;
* ... but this is implemented by unrolling the loop 5 times and renaming
* the variables (e,a,b,c,d) = (a',b',c',d',e') each iteration.
*/
#define subRound(a, b, c, d, e, f, k, data) \
 ( e += ROTL(5,a) + f(b, c, d) + k + data, b = ROTL(30, b) )
/*
* The above code is replicated 20 times for each of the 4 functions,
* using the next 20 values from the W[] array for "data" each time.
*/

/*
* Perform the SHA transformation. Note that this code, like MD5, seems to
* break some optimizing compilers due to the complexity of the expressions
* and the size of the basic block. It may be necessary to split it into
* sections, e.g. based on the four subrounds
*
* Note that this corrupts the sha->key area.
*/

static void
shaTransform(struct SHAContext *sha)
{
 register word32 A, B, C, D, E;
#if SHA_VERSION
		register word32 t;
	#endif

		/* Set up first buffer */
		A = sha->iv[0];
		B = sha->iv[1];
		C = sha->iv[2];
		D = sha->iv[3];
		E = sha->iv[4];

		/* Heavy mangling, in 4 sub-rounds of 20 interations each. */
		subRound( A, B, C, D, E, f1, K2, sha->key[ 0] );
		subRound( E, A, B, C, D, f1, K2, sha->key[ 1] );
		subRound( D, E, A, B, C, f1, K2, sha->key[ 2] );
		subRound( C, D, E, A, B, f1, K2, sha->key[ 3] );
		subRound( B, C, D, E, A, f1, K2, sha->key[ 4] );
		subRound( A, B, C, D, E, f1, K2, sha->key[ 5] );
		subRound( E, A, B, C, D, f1, K2, sha->key[ 6] );
		subRound( D, E, A, B, C, f1, K2, sha->key[ 7] );
		subRound( C, D, E, A, B, f1, K2, sha->key[ 8] );
		subRound( B, C, D, E, A, f1, K2, sha->key[ 9] );
		subRound( A, B, C, D, E, f1, K2, sha->key[10] );
		subRound( E, A, B, C, D, f1, K2, sha->key[11] );
		subRound( D, E, A, B, C, f1, K2, sha->key[12] );
		subRound( C, D, E, A, B, f1, K2, sha->key[13] );
		subRound( B, C, D, E, A, f1, K2, sha->key[14] );
		subRound( A, B, C, D, E, f1, K2, sha->key[15] );
		subRound( E, A, B, C, D, f1, K2, expand(sha->key, 16) );
		subRound( D, E, A, B, C, f1, K2, expand(sha->key, 17) );
		subRound( C, D, E, A, B, f1, K2, expand(sha->key, 18) );
		subRound( B, C, D, E, A, f1, K2, expand(sha->key, 19) );

		subRound( A, B, C, D, E, f2, K3, expand(sha->key, 20) );
		subRound( E, A, B, C, D, f2, K3, expand(sha->key, 21) );
		subRound( D, E, A, B, C, f2, K3, expand(sha->key, 22) );
		subRound( C, D, E, A, B, f2, K3, expand(sha->key, 23) );
		subRound( B, C, D, E, A, f2, K3, expand(sha->key, 24) );
		subRound( A, B, C, D, E, f2, K3, expand(sha->key, 25) );
		subRound( E, A, B, C, D, f2, K3, expand(sha->key, 26) );
		subRound( D, E, A, B, C, f2, K3, expand(sha->key, 27) );
		subRound( C, D, E, A, B, f2, K3, expand(sha->key, 28) );
		subRound( B, C, D, E, A, f2, K3, expand(sha->key, 29) );
		subRound( A, B, C, D, E, f2, K3, expand(sha->key, 30) );
		subRound( E, A, B, C, D, f2, K3, expand(sha->key, 31) );
		subRound( D, E, A, B, C, f2, K3, expand(sha->key, 32) );
		subRound( C, D, E, A, B, f2, K3, expand(sha->key, 33) );
		subRound( B, C, D, E, A, f2, K3, expand(sha->key, 34) );
		subRound( A, B, C, D, E, f2, K3, expand(sha->key, 35) );
		subRound( E, A, B, C, D, f2, K3, expand(sha->key, 36) );
		subRound( D, E, A, B, C, f2, K3, expand(sha->key, 37) );
		subRound( C, D, E, A, B, f2, K3, expand(sha->key, 38) );
		subRound( B, C, D, E, A, f2, K3, expand(sha->key, 39) );

		subRound( A, B, C, D, E, f3, K5, expand(sha->key, 40) );
		subRound( E, A, B, C, D, f3, K5, expand(sha->key, 41) );
		subRound( D, E, A, B, C, f3, K5, expand(sha->key, 42) );
		subRound( C, D, E, A, B, f3, K5, expand(sha->key, 43) );
		subRound( B, C, D, E, A, f3, K5, expand(sha->key, 44) );
		subRound( A, B, C, D, E, f3, K5, expand(sha->key, 45) );
		subRound( E, A, B, C, D, f3, K5, expand(sha->key, 46) );
		subRound( D, E, A, B, C, f3, K5, expand(sha->key, 47) );
		subRound( C, D, E, A, B, f3, K5, expand(sha->key, 48) );
		subRound( B, C, D, E, A, f3, K5, expand(sha->key, 49) );
		subRound( A, B, C, D, E, f3, K5, expand(sha->key, 50) );
		subRound( E, A, B, C, D, f3, K5, expand(sha->key, 51) );
		subRound( D, E, A, B, C, f3, K5, expand(sha->key, 52) );
		subRound( C, D, E, A, B, f3, K5, expand(sha->key, 53) );
		subRound( B, C, D, E, A, f3, K5, expand(sha->key, 54) );
		subRound( A, B, C, D, E, f3, K5, expand(sha->key, 55) );
		subRound( E, A, B, C, D, f3, K5, expand(sha->key, 56) );
		subRound( D, E, A, B, C, f3, K5, expand(sha->key, 57) );
		subRound( C, D, E, A, B, f3, K5, expand(sha->key, 58) );
		subRound( B, C, D, E, A, f3, K5, expand(sha->key, 59) );

		subRound( A, B, C, D, E, f4, K10, expand(sha->key, 60) );
		subRound( E, A, B, C, D, f4, K10, expand(sha->key, 61) );
		subRound( D, E, A, B, C, f4, K10, expand(sha->key, 62) );
		subRound( C, D, E, A, B, f4, K10, expand(sha->key, 63) );
		subRound( B, C, D, E, A, f4, K10, expand(sha->key, 64) );
		subRound( A, B, C, D, E, f4, K10, expand(sha->key, 65) );
		subRound( E, A, B, C, D, f4, K10, expand(sha->key, 66) );
		subRound( D, E, A, B, C, f4, K10, expand(sha->key, 67) );
		subRound( C, D, E, A, B, f4, K10, expand(sha->key, 68) );
		subRound( B, C, D, E, A, f4, K10, expand(sha->key, 69) );
		subRound( A, B, C, D, E, f4, K10, expand(sha->key, 70) );
		subRound( E, A, B, C, D, f4, K10, expand(sha->key, 71) );
		subRound( D, E, A, B, C, f4, K10, expand(sha->key, 72) );
		subRound( C, D, E, A, B, f4, K10, expand(sha->key, 73) );
		subRound( B, C, D, E, A, f4, K10, expand(sha->key, 74) );
		subRound( A, B, C, D, E, f4, K10, expand(sha->key, 75) );
		subRound( E, A, B, C, D, f4, K10, expand(sha->key, 76) );
		subRound( D, E, A, B, C, f4, K10, expandx(sha->key, 77) );
		subRound( C, D, E, A, B, f4, K10, expandx(sha->key, 78) );
		subRound( B, C, D, E, A, f4, K10, expandx(sha->key, 79) );

		/* Build message digest */
		sha->iv[0] += A;
		sha->iv[1] += B;
		sha->iv[2] += C;
		sha->iv[3] += D;
		sha->iv[4] += E;
	}