pgpsha.c

PGP—Pretty Good Privacy

/*
 * 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 1.15 1997/10/14 01:48:23 heller Exp $
 */

#include "pgpConfig.h"

#include <string.h>

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


/*
 * Shuffle the bytes into big-endian order within words, as per the
 * SHA spec.
 */
static void
shaByteSwap(PGPUInt32 *dest, PGPByte const *src, unsigned words)
{
	do {
		*dest++ = (PGPUInt32)((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)
{
	SHAContext *ctx = (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.
 * NOTE This is not declared as static because pgpRndPool.c references it.
 * (Sorry for that modularity violation.)
 */
void pgpSHATransform(PGPUInt32 *block, PGPUInt32 *key);
void
pgpSHATransform(PGPUInt32 *block, PGPUInt32 *key)
{
	register PGPUInt32 A, B, C, D, E;
#if SHA_VERSION
	register PGPUInt32 t;
#endif

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

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

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

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

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

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

/* Update SHA for a block of data. */

static void
shaUpdate(void *priv, void const *bufIn, PGPSize len)
{
	SHAContext *ctx = (SHAContext *)priv;