/*	$OpenBSD: sha2.c,v 1.6 2004/05/03 02:57:36 millert Exp $	*/

/*
 * FILE:	sha2.c
 * AUTHOR:	Aaron D. Gifford <me@aarongifford.com>
 * 
 * Copyright (c) 2000-2001, Aaron D. Gifford
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holder nor the names of contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTOR(S) ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTOR(S) BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $From: sha2.c,v 1.1 2001/11/08 00:01:51 adg Exp adg $
 */

#include <sys/param.h>
#include <sys/time.h>

/*
 * UNROLLED TRANSFORM LOOP NOTE:
 * You can define SHA2_UNROLL_TRANSFORM to use the unrolled transform
 * loop version for the hash transform rounds (defined using macros
 * later in this file).  Either define on the command line, for example:
 *
 *   cc -DSHA2_UNROLL_TRANSFORM -o sha2 sha2.c sha2prog.c
 *
 * or define below:
 *
 *   #define SHA2_UNROLL_TRANSFORM
 *
 */


/*** SHA-256 Machine Architecture Definitions *****************/
/*
 * BYTE_ORDER NOTE:
 *
 * Please make sure that your system defines BYTE_ORDER.  If your
 * architecture is little-endian, make sure it also defines
 * LITTLE_ENDIAN and that the two (BYTE_ORDER and LITTLE_ENDIAN) are
 * equivalent.
 *
 * If your system does not define the above, then you can do so by
 * hand like this:
 *
 *   #define LITTLE_ENDIAN 1234
 *   #define BIG_ENDIAN    4321
 *
 * And for little-endian machines, add:
 *
 *   #define BYTE_ORDER LITTLE_ENDIAN 
 *
 * Or for big-endian machines:
 *
 *   #define BYTE_ORDER BIG_ENDIAN
 *
 * The FreeBSD machine this was written on defines BYTE_ORDER
 * appropriately by including <sys/types.h> (which in turn includes
 * <machine/endian.h> where the appropriate definitions are actually
 * made).
 */
#if !defined(BYTE_ORDER) || (BYTE_ORDER != LITTLE_ENDIAN && BYTE_ORDER != BIG_ENDIAN)
#error Define BYTE_ORDER to be equal to either LITTLE_ENDIAN or BIG_ENDIAN
#endif


/*** SHA-256 Various Length Definitions ***********************/
/* NOTE: Most of these are in sha2.h */
#define SHA256_SHORT_BLOCK_LENGTH	(SHA256_BLOCK_LENGTH - 8)


/*** ENDIAN REVERSAL MACROS *******************************************/
#if BYTE_ORDER == LITTLE_ENDIAN
#define REVERSE32(w,x)	{ \
	u_int32_t tmp = (w); \
	tmp = (tmp >> 16) | (tmp << 16); \
	(x) = ((tmp & 0xff00ff00UL) >> 8) | ((tmp & 0x00ff00ffUL) << 8); \
}
#define REVERSE64(w,x)	{ \
	u_int64_t tmp = (w); \
	tmp = (tmp >> 32) | (tmp << 32); \
	tmp = ((tmp & 0xff00ff00ff00ff00ULL) >> 8) | \
	      ((tmp & 0x00ff00ff00ff00ffULL) << 8); \
	(x) = ((tmp & 0xffff0000ffff0000ULL) >> 16) | \
	      ((tmp & 0x0000ffff0000ffffULL) << 16); \
}
#endif /* BYTE_ORDER == LITTLE_ENDIAN */

/*
 * Macro for incrementally adding the unsigned 64-bit integer n to the
 * unsigned 128-bit integer (represented using a two-element array of
 * 64-bit words):
 */
#define ADDINC128(w,n)	{ \
	(w)[0] += (u_int64_t)(n); \
	if ((w)[0] < (n)) { \
		(w)[1]++; \
	} \
}

/*** THE SIX LOGICAL FUNCTIONS ****************************************/
/*
 * Bit shifting and rotation (used by the six SHA-XYZ logical functions:
 *
 *   NOTE:  The naming of R and S appears backwards here (R is a SHIFT and
 *   S is a ROTATION) because the SHA-256/384/512 description document
 *   (see http://csrc.nist.gov/cryptval/shs/sha256-384-512.pdf) uses this
 *   same "backwards" definition.
 */
/* Shift-right (used in SHA-256, SHA-384, and SHA-512): */
#define R(b,x) 		((x) >> (b))
/* 32-bit Rotate-right (used in SHA-256): */
#define S32(b,x)	(((x) >> (b)) | ((x) << (32 - (b))))
/* 64-bit Rotate-right (used in SHA-384 and SHA-512): */
#define S64(b,x)	(((x) >> (b)) | ((x) << (64 - (b))))

/* Two of six logical functions used in SHA-256: */
#define Ch(x,y,z)	(((x) & (y)) ^ ((~(x)) & (z)))
#define Maj(x,y,z)	(((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))

/* Four of six logical functions used in SHA-256: */
#define Sigma0_256(x)	(S32(2,  (x)) ^ S32(13, (x)) ^ S32(22, (x)))
#define Sigma1_256(x)	(S32(6,  (x)) ^ S32(11, (x)) ^ S32(25, (x)))
#define sigma0_256(x)	(S32(7,  (x)) ^ S32(18, (x)) ^ R(3 ,   (x)))
#define sigma1_256(x)	(S32(17, (x)) ^ S32(19, (x)) ^ R(10,   (x)))

/*** INTERNAL FUNCTION PROTOTYPES *************************************/
/* NOTE: These should not be accessed directly from outside this
 * library -- they are intended for private internal visibility/use
 * only.
 */
void SHA256_Transform(SHA256_CTX *, const u_int8_t *);


/*** SHA-XYZ INITIAL HASH VALUES AND CONSTANTS ************************/
/* Hash constant words K for SHA-256: */
static const u_int32_t K256[64] = {
	0x428a2f98UL, 0x71374491UL, 0xb5c0fbcfUL, 0xe9b5dba5UL,
	0x3956c25bUL, 0x59f111f1UL, 0x923f82a4UL, 0xab1c5ed5UL,
	0xd807aa98UL, 0x12835b01UL, 0x243185beUL, 0x550c7dc3UL,
	0x72be5d74UL, 0x80deb1feUL, 0x9bdc06a7UL, 0xc19bf174UL,
	0xe49b69c1UL, 0xefbe4786UL, 0x0fc19dc6UL, 0x240ca1ccUL,
	0x2de92c6fUL, 0x4a7484aaUL, 0x5cb0a9dcUL, 0x76f988daUL,
	0x983e5152UL, 0xa831c66dUL, 0xb00327c8UL, 0xbf597fc7UL,
	0xc6e00bf3UL, 0xd5a79147UL, 0x06ca6351UL, 0x14292967UL,
	0x27b70a85UL, 0x2e1b2138UL, 0x4d2c6dfcUL, 0x53380d13UL,
	0x650a7354UL, 0x766a0abbUL, 0x81c2c92eUL, 0x92722c85UL,
	0xa2bfe8a1UL, 0xa81a664bUL, 0xc24b8b70UL, 0xc76c51a3UL,
	0xd192e819UL, 0xd6990624UL, 0xf40e3585UL, 0x106aa070UL,
	0x19a4c116UL, 0x1e376c08UL, 0x2748774cUL, 0x34b0bcb5UL,
	0x391c0cb3UL, 0x4ed8aa4aUL, 0x5b9cca4fUL, 0x682e6ff3UL,
	0x748f82eeUL, 0x78a5636fUL, 0x84c87814UL, 0x8cc70208UL,
	0x90befffaUL, 0xa4506cebUL, 0xbef9a3f7UL, 0xc67178f2UL
};

/* Initial hash value H for SHA-256: */
static const u_int32_t sha256_initial_hash_value[8] = {
	0x6a09e667UL,
	0xbb67ae85UL,
	0x3c6ef372UL,
	0xa54ff53aUL,
	0x510e527fUL,
	0x9b05688cUL,
	0x1f83d9abUL,
	0x5be0cd19UL
};



/*** SHA-256: *********************************************************/
void
SHA256_Init(SHA256_CTX *context)
{
	if (context == NULL)
		return;
	bcopy(sha256_initial_hash_value, context->state, SHA256_DIGEST_LENGTH);
	bzero(context->buffer, SHA256_BLOCK_LENGTH);
	context->bitcount = 0;
}

#ifdef SHA2_UNROLL_TRANSFORM

/* Unrolled SHA-256 round macros: */

#define ROUND256_0_TO_15(a,b,c,d,e,f,g,h) do {				    \
	W256[j] = (u_int32_t)data[3] | ((u_int32_t)data[2] << 8) |	    \
	    ((u_int32_t)data[1] << 16) | ((u_int32_t)data[0] << 24);	    \
	data += 4;							    \
	T1 = (h) + Sigma1_256((e)) + Ch((e), (f), (g)) + K256[j] + W256[j]; \
	(d) += T1;							    \
	(h) = T1 + Sigma0_256((a)) + Maj((a), (b), (c));		    \
	j++;								    \
} while(0)

#define ROUND256(a,b,c,d,e,f,g,h) do {					    \
	s0 = W256[(j+1)&0x0f];						    \
	s0 = sigma0_256(s0);						    \
	s1 = W256[(j+14)&0x0f];						    \
	s1 = sigma1_256(s1);						    \
	T1 = (h) + Sigma1_256((e)) + Ch((e), (f), (g)) + K256[j] +	    \
	     (W256[j&0x0f] += s1 + W256[(j+9)&0x0f] + s0);		    \
	(d) += T1;							    \
	(h) = T1 + Sigma0_256((a)) + Maj((a), (b), (c));		    \
	j++;								    \
} while(0)

void
SHA256_Transform(SHA256_CTX *context, const u_int8_t *data)
{
	u_int32_t	a, b, c, d, e, f, g, h, s0, s1;
	u_int32_t	T1, *W256;
	int		j;

	W256 = (u_int32_t *)context->buffer;

	/* Initialize registers with the prev. intermediate value */
	a = context->state[0];
	b = context->state[1];
	c = context->state[2];
	d = context->state[3];
	e = context->state[4];
	f = context->state[5];
	g = context->state[6];
	h = context->state[7];

	j = 0;
	do {
		/* Rounds 0 to 15 (unrolled): */
		ROUND256_0_TO_15(a,b,c,d,e,f,g,h);
		ROUND256_0_TO_15(h,a,b,c,d,e,f,g);
		ROUND256_0_TO_15(g,h,a,b,c,d,e,f);
		ROUND256_0_TO_15(f,g,h,a,b,c,d,e);
		ROUND256_0_TO_15(e,f,g,h,a,b,c,d);
		ROUND256_0_TO_15(d,e,f,g,h,a,b,c);
		ROUND256_0_TO_15(c,d,e,f,g,h,a,b);
		ROUND256_0_TO_15(b,c,d,e,f,g,h,a);
	} while (j < 16);

	/* Now for the remaining rounds to 64: */
	do {
		ROUND256(a,b,c,d,e,f,g,h);
		ROUND256(h,a,b,c,d,e,f,g);
		ROUND256(g,h,a,b,c,d,e,f);
		ROUND256(f,g,h,a,b,c,d,e);
		ROUND256(e,f,g,h,a,b,c,d);
		ROUND256(d,e,f,g,h,a,b,c);
		ROUND256(c,d,e,f,g,h,a,b);
		ROUND256(b,c,d,e,f,g,h,a);
	} while (j < 64);

	/* Compute the current intermediate hash value */
	context->state[0] += a;
	context->state[1] += b;
	context->state[2] += c;
	context->state[3] += d;
	context->state[4] += e;
	context->state[5] += f;
	context->state[6] += g;
	context->state[7] += h;

	/* Clean up */
	a = b = c = d = e = f = g = h = T1 = 0;
}

#else /* SHA2_UNROLL_TRANSFORM */

void
SHA256_Transform(SHA256_CTX *context, const u_int8_t *data)
{
	u_int32_t	a, b, c, d, e, f, g, h, s0, s1;
	u_int32_t	T1, T2, *W256;
	int		j;

	W256 = (u_int32_t *)context->buffer;

	/* Initialize registers with the prev. intermediate value */
	a = context->state[0];
	b = context->state[1];
	c = context->state[2];
	d = context->state[3];
	e = context->state[4];
	f = context->state[5];
	g = context->state[6];
	h = context->state[7];

	j = 0;
	do {
		W256[j] = (u_int32_t)data[3] | ((u_int32_t)data[2] << 8) |
		    ((u_int32_t)data[1] << 16) | ((u_int32_t)data[0] << 24);
		data += 4;
		/* Apply the SHA-256 compression function to update a..h */
		T1 = h + Sigma1_256(e) + Ch(e, f, g) + K256[j] + W256[j];
		T2 = Sigma0_256(a) + Maj(a, b, c);
		h = g;
		g = f;
		f = e;
		e = d + T1;
		d = c;
		c = b;
		b = a;
		a = T1 + T2;

		j++;
	} while (j < 16);

	do {
		/* Part of the message block expansion: */
		s0 = W256[(j+1)&0x0f];
		s0 = sigma0_256(s0);
		s1 = W256[(j+14)&0x0f];	
		s1 = sigma1_256(s1);

		/* Apply the SHA-256 compression function to update a..h */
		T1 = h + Sigma1_256(e) + Ch(e, f, g) + K256[j] + 
		     (W256[j&0x0f] += s1 + W256[(j+9)&0x0f] + s0);
		T2 = Sigma0_256(a) + Maj(a, b, c);
		h = g;
		g = f;
		f = e;
		e = d + T1;
		d = c;
		c = b;
		b = a;
		a = T1 + T2;

		j++;
	} while (j < 64);

	/* Compute the current intermediate hash value */
	context->state[0] += a;
	context->state[1] += b;
	context->state[2] += c;
	context->state[3] += d;
	context->state[4] += e;
	context->state[5] += f;
	context->state[6] += g;
	context->state[7] += h;

	/* Clean up */
	a = b = c = d = e = f = g = h = T1 = T2 = 0;
}

#endif /* SHA2_UNROLL_TRANSFORM */

void
SHA256_Update(SHA256_CTX *context, const u_int8_t *data, size_t len)
{
	size_t	freespace, usedspace;

	/* Calling with no data is valid (we do nothing) */
	if (len == 0)
		return;

	usedspace = (context->bitcount >> 3) % SHA256_BLOCK_LENGTH;
	if (usedspace > 0) {
		/* Calculate how much free space is available in the buffer */
		freespace = SHA256_BLOCK_LENGTH - usedspace;

		if (len >= freespace) {
			/* Fill the buffer completely and process it */
			bcopy(data, &context->buffer[usedspace], freespace);
			context->bitcount += freespace << 3;
			len -= freespace;
			data += freespace;
			SHA256_Transform(context, context->buffer);
		} else {
			/* The buffer is not yet full */
			bcopy(data, &context->buffer[usedspace], len);
			context->bitcount += len << 3;
			/* Clean up: */
			usedspace = freespace = 0;
			return;
		}
	}
	while (len >= SHA256_BLOCK_LENGTH) {
		/* Process as many complete blocks as we can */
		SHA256_Transform(context, data);
		context->bitcount += SHA256_BLOCK_LENGTH << 3;
		len -= SHA256_BLOCK_LENGTH;
		data += SHA256_BLOCK_LENGTH;
	}
	if (len > 0) {
		/* There's left-overs, so save 'em */
		bcopy(data, context->buffer, len);
		context->bitcount += len << 3;
	}
	/* Clean up: */
	usedspace = freespace = 0;
}

void
SHA256_Final(u_int8_t digest[], SHA256_CTX *context)
{
	u_int32_t	*d = (u_int32_t *)digest;
	unsigned int	usedspace;

	/* If no digest buffer is passed, we don't bother doing this: */
	if (digest != NULL) {
		usedspace = (context->bitcount >> 3) % SHA256_BLOCK_LENGTH;
#if BYTE_ORDER == LITTLE_ENDIAN
		/* Convert FROM host byte order */
		REVERSE64(context->bitcount,context->bitcount);
#endif
		if (usedspace > 0) {
			/* Begin padding with a 1 bit: */
			context->buffer[usedspace++] = 0x80;

			if (usedspace <= SHA256_SHORT_BLOCK_LENGTH) {
				/* Set-up for the last transform: */
				bzero(&context->buffer[usedspace], SHA256_SHORT_BLOCK_LENGTH - usedspace);
			} else {
				if (usedspace < SHA256_BLOCK_LENGTH) {
					bzero(&context->buffer[usedspace], SHA256_BLOCK_LENGTH - usedspace);
				}
				/* Do second-to-last transform: */
				SHA256_Transform(context, context->buffer);

				/* And set-up for the last transform: */
				bzero(context->buffer, SHA256_SHORT_BLOCK_LENGTH);
			}
		} else {
			/* Set-up for the last transform: */
			bzero(context->buffer, SHA256_SHORT_BLOCK_LENGTH);

			/* Begin padding with a 1 bit: */
			*context->buffer = 0x80;
		}
		/* Set the bit count: */
		*(u_int64_t *)&context->buffer[SHA256_SHORT_BLOCK_LENGTH] = context->bitcount;

		/* Final transform: */
		SHA256_Transform(context, context->buffer);

#if BYTE_ORDER == LITTLE_ENDIAN
		{
			/* Convert TO host byte order */
			int	j;
			for (j = 0; j < 8; j++) {
				REVERSE32(context->state[j],context->state[j]);
				*d++ = context->state[j];
			}
		}
#else
		bcopy(context->state, d, SHA256_DIGEST_LENGTH);
#endif
	}

	/* Clean up state data: */
	bzero(context, sizeof(*context));
	usedspace = 0;
}
