/*
 * 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.
 *
 * $Id: sha2.c 14578 2004-11-19 13:57:45Z dom $
 */

#include <string.h>	/* memcpy()/memset() or bcopy()/bzero() */
#include <sys/types.h>
#include "sha2.h"
/*** 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
 * equivilent.
 *
 * 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

#define SHA256_SHORT_BLOCK_LENGTH	(SHA256_BLOCK_LENGTH - 8)

/*** ENDIAN REVERSAL MACROS *******************************************/
#if BYTE_ORDER == LITTLE_ENDIAN
#define REVERSE32(w,x)	{ \
	uint32 tmp = (w); \
	tmp = (tmp >> 16) | (tmp << 16); \
	(x) = ((tmp & 0xff00ff00UL) >> 8) | ((tmp & 0x00ff00ffUL) << 8); \
}
#define REVERSE64(w,x)	{ \
	uint64 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] += (uint64)(n); \
	if ((w)[0] < (n)) { \
		(w)[1]++; \
	} \
}

/*
 * Macros for copying blocks of memory and for zeroing out ranges
 * of memory.  Using these macros makes it easy to switch from
 * using memset()/memcpy() and using bzero()/bcopy().
 *
 * Please define either SHA2_USE_MEMSET_MEMCPY or define
 * SHA2_USE_BZERO_BCOPY depending on which function set you
 * choose to use:
 */
#if !defined(SHA2_USE_MEMSET_MEMCPY) && !defined(SHA2_USE_BZERO_BCOPY)
/* Default to memset()/memcpy() if no option is specified */
#define	SHA2_USE_MEMSET_MEMCPY	1
#endif
#if defined(SHA2_USE_MEMSET_MEMCPY) && defined(SHA2_USE_BZERO_BCOPY)
/* Abort with an error if BOTH options are defined */
#error Define either SHA2_USE_MEMSET_MEMCPY or SHA2_USE_BZERO_BCOPY, not both!
#endif

#ifdef SHA2_USE_MEMSET_MEMCPY
#define MEMSET_BZERO(p,l)	memset((p), 0, (l))
#define MEMCPY_BCOPY(d,s,l)	memcpy((d), (s), (l))
#endif
#ifdef SHA2_USE_BZERO_BCOPY
#define MEMSET_BZERO(p,l)	bzero((p), (l))
#define MEMCPY_BCOPY(d,s,l)	bcopy((s), (d), (l))
#endif


/*** 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, SHA-384, and SHA-512: */
#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.
 */
static void SHA256_Transform(sha256_ctx*, const uint32*);

/*** SHA-XYZ INITIAL HASH VALUES AND CONSTANTS ************************/
/* Hash constant words K for SHA-256: */
const static uint32 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: */
const static uint32 sha256_initial_hash_value[8] = {
  0x6a09e667UL,
  0xbb67ae85UL,
  0x3c6ef372UL,
  0xa54ff53aUL,
  0x510e527fUL,
  0x9b05688cUL,
  0x1f83d9abUL,
  0x5be0cd19UL
};

/*** SHA-256: *********************************************************/
void sha256_begin(sha256_ctx *ctx) {
  if (ctx == (sha256_ctx*)0) {
    return;
  }
  MEMCPY_BCOPY(ctx->state, sha256_initial_hash_value, SHA256_DIGEST_LENGTH);
  MEMSET_BZERO(ctx->buffer, SHA256_BLOCK_LENGTH);
  ctx->bitcount = 0;
}


void SHA256_Transform(sha256_ctx* ctx, const uint32* data) {
  uint32	a, b, c, d, e, f, g, h, s0, s1;
  uint32	T1, T2, *W256;
  int		j;

  W256 = (uint32*)ctx->buffer;

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

  j = 0;
  do {
#if BYTE_ORDER == LITTLE_ENDIAN
    /* Copy data while converting to host byte order */
    REVERSE32(*data++,W256[j]);
    /* Apply the SHA-256 compression function to update a..h */
    T1 = h + Sigma1_256(e) + Ch(e, f, g) + K256[j] + W256[j];
#else /* BYTE_ORDER == LITTLE_ENDIAN */
    /* Apply the SHA-256 compression function to update a..h with copy */
    T1 = h + Sigma1_256(e) + Ch(e, f, g) + K256[j] + (W256[j] = *data++);
#endif /* BYTE_ORDER == LITTLE_ENDIAN */
    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 */
  ctx->state[0] += a;
  ctx->state[1] += b;
  ctx->state[2] += c;
  ctx->state[3] += d;
  ctx->state[4] += e;
  ctx->state[5] += f;
  ctx->state[6] += g;
  ctx->state[7] += h;

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

void sha256_hash(const uint8 *data, uint32 len, sha256_ctx * ctx)
{
  unsigned int	freespace, usedspace;

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

  usedspace = (ctx->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 */
      MEMCPY_BCOPY(&ctx->buffer[usedspace], data, freespace);
      ctx->bitcount += freespace << 3;
      len -= freespace;
      data += freespace;
      SHA256_Transform(ctx, (uint32*)ctx->buffer);
    } else {
      /* The buffer is not yet full */
      MEMCPY_BCOPY(&ctx->buffer[usedspace], data, len);
      ctx->bitcount += len << 3;
      /* Clean up: */
      usedspace = freespace = 0;
      return;
    }
  }
  while (len >= SHA256_BLOCK_LENGTH) {
    /* Process as many complete blocks as we can */
    SHA256_Transform(ctx, (uint32*)data);
    ctx->bitcount += SHA256_BLOCK_LENGTH << 3;
    len -= SHA256_BLOCK_LENGTH;
    data += SHA256_BLOCK_LENGTH;
  }
  if (len > 0) {
    /* There's left-overs, so save 'em */
    MEMCPY_BCOPY(ctx->buffer, data, len);
    ctx->bitcount += len << 3;
  }
  /* Clean up: */
  usedspace = freespace = 0;
}

void sha256_end(uint8 *digest, sha256_ctx *ctx) {
  uint32	*d = (uint32*)digest;
  unsigned int	usedspace;
  
  /* If no digest buffer is passed, we don't bother doing this: */
  usedspace = (ctx->bitcount >> 3) % SHA256_BLOCK_LENGTH;
#if BYTE_ORDER == LITTLE_ENDIAN
  /* Convert FROM host byte order */
  REVERSE64(ctx->bitcount,ctx->bitcount);
#endif
  if (usedspace > 0) {
    /* Begin padding with a 1 bit: */
    ctx->buffer[usedspace++] = 0x80;

    if (usedspace <= SHA256_SHORT_BLOCK_LENGTH) {
      /* Set-up for the last transform: */
      MEMSET_BZERO(&ctx->buffer[usedspace], SHA256_SHORT_BLOCK_LENGTH - usedspace);
    } else {
      if (usedspace < SHA256_BLOCK_LENGTH) {
	MEMSET_BZERO(&ctx->buffer[usedspace], SHA256_BLOCK_LENGTH - usedspace);
      }
      /* Do second-to-last transform: */
      SHA256_Transform(ctx, (uint32*)ctx->buffer);

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

    /* Begin padding with a 1 bit: */
    *ctx->buffer = 0x80;
  }
  /* Set the bit count: */
  *(uint64*)&ctx->buffer[SHA256_SHORT_BLOCK_LENGTH] = ctx->bitcount;

  /* Final transform: */
  SHA256_Transform(ctx, (uint32*)ctx->buffer);

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

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