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/* --------------------------------- SHS.CC ------------------------------- */
 
/*
 * NIST proposed Secure Hash Standard.
 *
 * Written 2 September 1992, Peter C. Gutmann.
 * This implementation placed in the public domain.
 *
 * Comments to pgut1@cs.aukuni.ac.nz
 */
 
// Force C++ compiler to use Java-style EH, so we don't have to link with
// libstdc++.
#pragma GCC java_exceptions
 
#include <string.h>
#include "shs.h"
 
/* The SHS f()-functions */
 
#define f1(x,y,z)   ( ( x & y ) | ( ~x & z ) )		  /* Rounds  0-19 */
#define f2(x,y,z)   ( x ^ y ^ z )			  /* Rounds 20-39 */
#define f3(x,y,z)   ( ( x & y ) | ( x & z ) | ( y & z ) ) /* Rounds 40-59 */
#define f4(x,y,z)   ( x ^ y ^ z )			  /* Rounds 60-79 */
 
/* The SHS Mysterious Constants */
 
#define K1  0x5A827999L 	/* Rounds  0-19 */
#define K2  0x6ED9EBA1L 	/* Rounds 20-39 */
#define K3  0x8F1BBCDCL 	/* Rounds 40-59 */
#define K4  0xCA62C1D6L 	/* Rounds 60-79 */
 
/* SHS initial values */
 
#define h0init	0x67452301L
#define h1init	0xEFCDAB89L
#define h2init	0x98BADCFEL
#define h3init	0x10325476L
#define h4init	0xC3D2E1F0L
 
/* 32-bit rotate - kludged with shifts */
 
#define S(n,X)	((X << n) | (X >> (32 - n)))
 
/* The initial expanding function */
 
#define expand(count)	W [count] = W [count - 3] ^ W [count - 8] ^ W [count - 14] ^ W [count - 16]
 
/* The four SHS sub-rounds */
 
#define subRound1(count)    \
	{ \
		temp = S (5, A) + f1 (B, C, D) + E + W [count] + K1; \
		E = D; \
		D = C; \
		C = S (30, B); \
		B = A; \
		A = temp; \
	}
 
#define subRound2(count)    \
	{ \
		temp = S (5, A) + f2 (B, C, D) + E + W [count] + K2; \
		E = D; \
		D = C; \
		C = S (30, B); \
		B = A; \
		A = temp; \
	}
 
#define subRound3(count)    \
	{ \
		temp = S (5, A) + f3 (B, C, D) + E + W [count] + K3; \
		E = D; \
		D = C; \
		C = S (30, B); \
		B = A; \
		A = temp; \
	}
 
#define subRound4(count)    \
	{ \
		temp = S (5, A) + f4 (B, C, D) + E + W [count] + K4; \
		E = D; \
		D = C; \
		C = S (30, B); \
		B = A; \
		A = temp; \
	}
 
/* The two buffers of 5 32-bit words */
 
uint32_t h0, h1, h2, h3, h4;
uint32_t A, B, C, D, E;
 
local void byteReverse OF((uint32_t *buffer, int byteCount));
void shsTransform OF((SHS_INFO *shsInfo));
 
/* Initialize the SHS values */
 
void shsInit (SHS_INFO *shsInfo)
{
	/* Set the h-vars to their initial values */
	shsInfo->digest [0] = h0init;
	shsInfo->digest [1] = h1init;
	shsInfo->digest [2] = h2init;
	shsInfo->digest [3] = h3init;
	shsInfo->digest [4] = h4init;
 
	/* Initialise bit count */
	shsInfo->countLo = shsInfo->countHi = 0L;
}
 
/*
 * Perform the SHS transformation.  Note that this code, like MD5, seems to
 * break some optimizing compilers - it may be necessary to split it into
 * sections, eg based on the four subrounds
 */
 
void shsTransform (SHS_INFO *shsInfo)
{
       uint32_t W [80], temp;
	int i;
 
	/* Step A.	Copy the data buffer into the local work buffer */
	for (i = 0; i < 16; i++)
		W [i] = shsInfo->data [i];
 
	/* Step B.	Expand the 16 words into 64 temporary data words */
	expand (16); expand (17); expand (18); expand (19); expand (20);
	expand (21); expand (22); expand (23); expand (24); expand (25);
	expand (26); expand (27); expand (28); expand (29); expand (30);
	expand (31); expand (32); expand (33); expand (34); expand (35);
	expand (36); expand (37); expand (38); expand (39); expand (40);
	expand (41); expand (42); expand (43); expand (44); expand (45);
	expand (46); expand (47); expand (48); expand (49); expand (50);
	expand (51); expand (52); expand (53); expand (54); expand (55);
	expand (56); expand (57); expand (58); expand (59); expand (60);
	expand (61); expand (62); expand (63); expand (64); expand (65);
	expand (66); expand (67); expand (68); expand (69); expand (70);
	expand (71); expand (72); expand (73); expand (74); expand (75);
	expand (76); expand (77); expand (78); expand (79);
 
	/* Step C.	Set up first buffer */
	A = shsInfo->digest [0];
	B = shsInfo->digest [1];
	C = shsInfo->digest [2];
	D = shsInfo->digest [3];
	E = shsInfo->digest [4];
 
	/* Step D.	Serious mangling, divided into four sub-rounds */
	subRound1  (0); subRound1  (1); subRound1  (2); subRound1  (3);
	subRound1  (4); subRound1  (5); subRound1  (6); subRound1  (7);
	subRound1  (8); subRound1  (9); subRound1 (10); subRound1 (11);
	subRound1 (12); subRound1 (13); subRound1 (14); subRound1 (15);
	subRound1 (16); subRound1 (17); subRound1 (18); subRound1 (19);
 
	subRound2 (20); subRound2 (21); subRound2 (22); subRound2 (23);
	subRound2 (24); subRound2 (25); subRound2 (26); subRound2 (27);
	subRound2 (28); subRound2 (29); subRound2 (30); subRound2 (31);
	subRound2 (32); subRound2 (33); subRound2 (34); subRound2 (35);
	subRound2 (36); subRound2 (37); subRound2 (38); subRound2 (39);
 
	subRound3 (40); subRound3 (41); subRound3 (42); subRound3 (43);
	subRound3 (44); subRound3 (45); subRound3 (46); subRound3 (47);
	subRound3 (48); subRound3 (49); subRound3 (50); subRound3 (51);
	subRound3 (52); subRound3 (53); subRound3 (54); subRound3 (55);
	subRound3 (56); subRound3 (57); subRound3 (58); subRound3 (59);
 
	subRound4 (60); subRound4 (61); subRound4 (62); subRound4 (63);
	subRound4 (64); subRound4 (65); subRound4 (66); subRound4 (67);
	subRound4 (68); subRound4 (69); subRound4 (70); subRound4 (71);
	subRound4 (72); subRound4 (73); subRound4 (74); subRound4 (75);
	subRound4 (76); subRound4 (77); subRound4 (78); subRound4 (79);
 
	/* Step E.	Build message digest */
	shsInfo->digest [0] += A;
	shsInfo->digest [1] += B;
	shsInfo->digest [2] += C;
	shsInfo->digest [3] += D;
	shsInfo->digest [4] += E;
}
 
local void byteReverse (uint32_t *buffer, int byteCount)
{
       uint32_t value;
	int count;
 
	/*
	 * Find out what the byte order is on this machine.
	 * Big endian is for machines that place the most significant byte
	 * first (eg. Sun SPARC). Little endian is for machines that place
	 * the least significant byte first (eg. VAX).
	 *
	 * We figure out the byte order by stuffing a 2 byte string into a
	 * short and examining the left byte. '@' = 0x40  and  'P' = 0x50
	 * If the left byte is the 'high' byte, then it is 'big endian'.
	 * If the left byte is the 'low' byte, then the machine is 'little
	 * endian'.
	 *
	 *                          -- Shawn A. Clifford (sac@eng.ufl.edu)
	 */
 
	/*
	 * Several bugs fixed       -- Pat Myrto (pat@rwing.uucp)
	 */
 
	if ((*(unsigned short *) ("@P") >> 8) == '@')
		return;
 
       byteCount /= sizeof (uint32_t);
	for (count = 0; count < byteCount; count++) {
		value = (buffer [count] << 16) | (buffer [count] >> 16);
		buffer [count] = ((value & 0xFF00FF00L) >> 8) | ((value & 0x00FF00FFL) << 8);
	}
}
 
/*
 * Update SHS for a block of data.  This code assumes that the buffer size is
 * a multiple of SHS_BLOCKSIZE bytes long, which makes the code a lot more
 * efficient since it does away with the need to handle partial blocks
 * between calls to shsUpdate()
 */
 
void shsUpdate (SHS_INFO *shsInfo, uint8_t *buffer, int count)
{
	/* Update bitcount */
       if ((shsInfo->countLo + ((uint32_t) count << 3)) < shsInfo->countLo)
		 shsInfo->countHi++;	/* Carry from low to high bitCount */
       shsInfo->countLo += ((uint32_t) count << 3);
       shsInfo->countHi += ((uint32_t) count >> 29);
 
	/* Process data in SHS_BLOCKSIZE chunks */
	while (count >= SHS_BLOCKSIZE) {
		memcpy (shsInfo->data, buffer, SHS_BLOCKSIZE);
		byteReverse (shsInfo->data, SHS_BLOCKSIZE);
		shsTransform (shsInfo);
		buffer += SHS_BLOCKSIZE;
		count -= SHS_BLOCKSIZE;
	}
 
	/*
	 * Handle any remaining bytes of data.
	 * This should only happen once on the final lot of data
	 */
	memcpy (shsInfo->data, buffer, count);
}
 
void shsFinal (SHS_INFO *shsInfo)
{
	int count;
       uint32_t lowBitcount = shsInfo->countLo, highBitcount = shsInfo->countHi;
 
	/* Compute number of bytes mod 64 */
	count = (int) ((shsInfo->countLo >> 3) & 0x3F);
 
	/*
	 * Set the first char of padding to 0x80.
	 * This is safe since there is always at least one byte free
	 */
       ((uint8_t *) shsInfo->data) [count++] = 0x80;
 
	/* Pad out to 56 mod 64 */
	if (count > 56) {
		/* Two lots of padding:  Pad the first block to 64 bytes */
               memset ((uint8_t *) shsInfo->data + count, 0, 64 - count);
		byteReverse (shsInfo->data, SHS_BLOCKSIZE);
		shsTransform (shsInfo);
 
		/* Now fill the next block with 56 bytes */
		memset (shsInfo->data, 0, 56);
	} else
		/* Pad block to 56 bytes */
               memset ((uint8_t *) shsInfo->data + count, 0, 56 - count);
	byteReverse (shsInfo->data, SHS_BLOCKSIZE);
 
	/* Append length in bits and transform */
	shsInfo->data [14] = highBitcount;
	shsInfo->data [15] = lowBitcount;
 
	shsTransform (shsInfo);
	byteReverse (shsInfo->data, SHS_DIGESTSIZE);
}