libs/signature/src/sha256.c - rocketmq-client-cpp - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.
  * The ASF licenses this file to You under the Apache License, Version 2.0
  * (the "License"); you may not use this file except in compliance with
  * the License.  You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include "sha256.h"

 #include <stddef.h>
 #include <string.h>

 #if USE_UNLOCKED_IO
 # include "unlocked-io.h"
 #endif

 #ifdef __cplusplus
 namespace rocketmqSignature {
 #endif

 #ifdef WORDS_BIGENDIAN
 # define SWAP(n) (n)
 #else
 # define SWAP(n) \
     (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
 #endif

 #define BLOCKSIZE 4096
 #if BLOCKSIZE % 64 != 0
 # error "invalid BLOCKSIZE"
 #endif

 /* This array contains the bytes used to pad the buffer to the next
    64-byte boundary.  */
 static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */ };


 /*
   Takes a pointer to a 256 bit block of data (eight 32 bit ints) and
   intializes it to the start constants of the SHA256 algorithm.  This
   must be called before using hash in the call to sha256_hash
 */
 void
 sha256_init_ctx (struct sha256_ctx *ctx)
 {
   ctx->state[0] = 0x6a09e667UL;
   ctx->state[1] = 0xbb67ae85UL;
   ctx->state[2] = 0x3c6ef372UL;
   ctx->state[3] = 0xa54ff53aUL;
   ctx->state[4] = 0x510e527fUL;
   ctx->state[5] = 0x9b05688cUL;
   ctx->state[6] = 0x1f83d9abUL;
   ctx->state[7] = 0x5be0cd19UL;

   ctx->total[0] = ctx->total[1] = 0;
   ctx->buflen = 0;
 }

 void
 sha224_init_ctx (struct sha256_ctx *ctx)
 {
   ctx->state[0] = 0xc1059ed8UL;
   ctx->state[1] = 0x367cd507UL;
   ctx->state[2] = 0x3070dd17UL;
   ctx->state[3] = 0xf70e5939UL;
   ctx->state[4] = 0xffc00b31UL;
   ctx->state[5] = 0x68581511UL;
   ctx->state[6] = 0x64f98fa7UL;
   ctx->state[7] = 0xbefa4fa4UL;

   ctx->total[0] = ctx->total[1] = 0;
   ctx->buflen = 0;
 }

 /* Copy the value from v into the memory location pointed to by *cp,
    If your architecture allows unaligned access this is equivalent to
    * (uint32_t *) cp = v  */
 #ifdef WIN32
 static _inline void
 #else
 static __inline__ void
 #endif
 set_uint32 (char *cp, uint32_t v)
 {
   memcpy (cp, &v, sizeof v);
 }

 /* Put result from CTX in first 32 bytes following RESBUF.  The result
    must be in little endian byte order.  */
 void *
 sha256_read_ctx (const struct sha256_ctx *ctx, void *resbuf)
 {
   int i;
   char *r = (char*)resbuf;

   for (i = 0; i < 8; i++)
     set_uint32 (r + i * sizeof ctx->state[0], SWAP (ctx->state[i]));

   return resbuf;
 }

 void *
 sha224_read_ctx (const struct sha256_ctx *ctx, void *resbuf)
 {
   int i;
   char *r = (char*)resbuf;

   for (i = 0; i < 7; i++)
     set_uint32 (r + i * sizeof ctx->state[0], SWAP (ctx->state[i]));

   return resbuf;
 }

 /* Process the remaining bytes in the internal buffer and the usual
    prolog according to the standard and write the result to RESBUF.  */
 static void
 sha256_conclude_ctx (struct sha256_ctx *ctx)
 {
   /* Take yet unprocessed bytes into account.  */
   size_t bytes = ctx->buflen;
   size_t size = (bytes < 56) ? 64 / 4 : 64 * 2 / 4;

   /* Now count remaining bytes.  */
   ctx->total[0] += bytes;
   if (ctx->total[0] < bytes)
     ++ctx->total[1];

   /* Put the 64-bit file length in *bits* at the end of the buffer.
      Use set_uint32 rather than a simple assignment, to avoid risk of
      unaligned access.  */
   set_uint32 ((char *) &ctx->buffer[size - 2],
 	      SWAP ((ctx->total[1] << 3) | (ctx->total[0] >> 29)));
   set_uint32 ((char *) &ctx->buffer[size - 1],
 	      SWAP (ctx->total[0] << 3));

   memcpy (&((char *) ctx->buffer)[bytes], fillbuf, (size - 2) * 4 - bytes);

   /* Process last bytes.  */
   sha256_process_block (ctx->buffer, size * 4, ctx);
 }

 void *
 sha256_finish_ctx (struct sha256_ctx *ctx, void *resbuf)
 {
   sha256_conclude_ctx (ctx);
   return sha256_read_ctx (ctx, resbuf);
 }

 void *
 sha224_finish_ctx (struct sha256_ctx *ctx, void *resbuf)
 {
   sha256_conclude_ctx (ctx);
   return sha224_read_ctx (ctx, resbuf);
 }

 /* Compute SHA256 message digest for bytes read from STREAM.  The
    resulting message digest number will be written into the 32 bytes
    beginning at RESBLOCK.  */
 int
 sha256_stream (FILE *stream, void *resblock)
 {
   struct sha256_ctx ctx;
   char buffer[BLOCKSIZE + 72];
   size_t sum;

   /* Initialize the computation context.  */
   sha256_init_ctx (&ctx);

   /* Iterate over full file contents.  */
   while (1)
     {
       /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
 	 computation function processes the whole buffer so that with the
 	 next round of the loop another block can be read.  */
       size_t n;
       sum = 0;

       /* Read block.  Take care for partial reads.  */
       while (1)
 	{
 	  n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);

 	  sum += n;

 	  if (sum == BLOCKSIZE)
 	    break;

 	  if (n == 0)
 	    {
 	      /* Check for the error flag IFF N == 0, so that we don't
 		 exit the loop after a partial read due to e.g., EAGAIN
 		 or EWOULDBLOCK.  */
 	      if (ferror (stream))
 		return 1;
 	      goto process_partial_block;
 	    }

 	  /* We've read at least one byte, so ignore errors.  But always
 	     check for EOF, since feof may be true even though N > 0.
 	     Otherwise, we could end up calling fread after EOF.  */
 	  if (feof (stream))
 	    goto process_partial_block;
 	}

       /* Process buffer with BLOCKSIZE bytes.  Note that
 			BLOCKSIZE % 64 == 0
        */
       sha256_process_block (buffer, BLOCKSIZE, &ctx);
     }

  process_partial_block:;

   /* Process any remaining bytes.  */
   if (sum > 0)
     sha256_process_bytes (buffer, sum, &ctx);

   /* Construct result in desired memory.  */
   sha256_finish_ctx (&ctx, resblock);
   return 0;
 }

 /* FIXME: Avoid code duplication */
 int
 sha224_stream (FILE *stream, void *resblock)
 {
   struct sha256_ctx ctx;
   char buffer[BLOCKSIZE + 72];
   size_t sum;

   /* Initialize the computation context.  */
   sha224_init_ctx (&ctx);

   /* Iterate over full file contents.  */
   while (1)
     {
       /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
 	 computation function processes the whole buffer so that with the
 	 next round of the loop another block can be read.  */
       size_t n;
       sum = 0;

       /* Read block.  Take care for partial reads.  */
       while (1)
 	{
 	  n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);

 	  sum += n;

 	  if (sum == BLOCKSIZE)
 	    break;

 	  if (n == 0)
 	    {
 	      /* Check for the error flag IFF N == 0, so that we don't
 		 exit the loop after a partial read due to e.g., EAGAIN
 		 or EWOULDBLOCK.  */
 	      if (ferror (stream))
 		return 1;
 	      goto process_partial_block;
 	    }

 	  /* We've read at least one byte, so ignore errors.  But always
 	     check for EOF, since feof may be true even though N > 0.
 	     Otherwise, we could end up calling fread after EOF.  */
 	  if (feof (stream))
 	    goto process_partial_block;
 	}

       /* Process buffer with BLOCKSIZE bytes.  Note that
 			BLOCKSIZE % 64 == 0
        */
       sha256_process_block (buffer, BLOCKSIZE, &ctx);
     }

  process_partial_block:;

   /* Process any remaining bytes.  */
   if (sum > 0)
     sha256_process_bytes (buffer, sum, &ctx);

   /* Construct result in desired memory.  */
   sha224_finish_ctx (&ctx, resblock);
   return 0;
 }

 /* Compute SHA512 message digest for LEN bytes beginning at BUFFER.  The
    result is always in little endian byte order, so that a byte-wise
    output yields to the wanted ASCII representation of the message
    digest.  */
 void *
 sha256_buffer (const char *buffer, size_t len, void *resblock)
 {
   struct sha256_ctx ctx;

   /* Initialize the computation context.  */
   sha256_init_ctx (&ctx);

   /* Process whole buffer but last len % 64 bytes.  */
   sha256_process_bytes (buffer, len, &ctx);

   /* Put result in desired memory area.  */
   return sha256_finish_ctx (&ctx, resblock);
 }

 void *
 sha224_buffer (const char *buffer, size_t len, void *resblock)
 {
   struct sha256_ctx ctx;

   /* Initialize the computation context.  */
   sha224_init_ctx (&ctx);

   /* Process whole buffer but last len % 64 bytes.  */
   sha256_process_bytes (buffer, len, &ctx);

   /* Put result in desired memory area.  */
   return sha224_finish_ctx (&ctx, resblock);
 }

 void
 sha256_process_bytes (const void *buffer, size_t len, struct sha256_ctx *ctx)
 {
   /* When we already have some bits in our internal buffer concatenate
      both inputs first.  */
   if (ctx->buflen != 0)
     {
       size_t left_over = ctx->buflen;
       size_t add = 128 - left_over > len ? len : 128 - left_over;

       memcpy (&((char *) ctx->buffer)[left_over], buffer, add);
       ctx->buflen += add;

       if (ctx->buflen > 64)
 	{
 	  sha256_process_block (ctx->buffer, ctx->buflen & ~63, ctx);

 	  ctx->buflen &= 63;
 	  /* The regions in the following copy operation cannot overlap.  */
 	  memcpy (ctx->buffer,
 		  &((char *) ctx->buffer)[(left_over + add) & ~63],
 		  ctx->buflen);
 	}

       buffer = (const char *) buffer + add;
       len -= add;
     }

   /* Process available complete blocks.  */
   if (len >= 64)
     {
 #if !_STRING_ARCH_unaligned
 # define alignof(type) offsetof (struct { char c; type x; }, x)
 # define UNALIGNED_P(p) (((size_t) p) % alignof (uint32_t) != 0)
       if (UNALIGNED_P (buffer))
 	while (len > 64)
 	  {
 	    sha256_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
 	    buffer = (const char *) buffer + 64;
 	    len -= 64;
 	  }
       else
 #endif
 	{
 	  sha256_process_block (buffer, len & ~63, ctx);
 	  buffer = (const char *) buffer + (len & ~63);
 	  len &= 63;
 	}
     }

   /* Move remaining bytes in internal buffer.  */
   if (len > 0)
     {
       size_t left_over = ctx->buflen;

       memcpy (&((char *) ctx->buffer)[left_over], buffer, len);
       left_over += len;
       if (left_over >= 64)
 	{
 	  sha256_process_block (ctx->buffer, 64, ctx);
 	  left_over -= 64;
 	  memcpy (ctx->buffer, &ctx->buffer[16], left_over);
 	}
       ctx->buflen = left_over;
     }
 }

 /* --- Code below is the primary difference between sha1.c and sha256.c --- */

 /* SHA256 round constants */
 #define K(I) sha256_round_constants[I]
 static const uint32_t sha256_round_constants[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,
 };

 /* Round functions.  */
 #define F2(A,B,C) ( ( A & B ) | ( C & ( A | B ) ) )
 #define F1(E,F,G) ( G ^ ( E & ( F ^ G ) ) )

 /* Process LEN bytes of BUFFER, accumulating context into CTX.
    It is assumed that LEN % 64 == 0.
    Most of this code comes from GnuPG's cipher/sha1.c.  */

 void
 sha256_process_block (const void *buffer, size_t len, struct sha256_ctx *ctx)
 {
   const uint32_t *words = (const uint32_t *)buffer;
   size_t nwords = len / sizeof (uint32_t);
   const uint32_t *endp = words + nwords;
   uint32_t x[16];
   uint32_t a = ctx->state[0];
   uint32_t b = ctx->state[1];
   uint32_t c = ctx->state[2];
   uint32_t d = ctx->state[3];
   uint32_t e = ctx->state[4];
   uint32_t f = ctx->state[5];
   uint32_t g = ctx->state[6];
   uint32_t h = ctx->state[7];

   /* First increment the byte count.  FIPS PUB 180-2 specifies the possible
      length of the file up to 2^64 bits.  Here we only compute the
      number of bytes.  Do a double word increment.  */
   ctx->total[0] += len;
   if (ctx->total[0] < len)
     ++ctx->total[1];

 #define rol(x, n) (((x) << (n)) | ((x) >> (32 - (n))))
 #define S0(x) (rol(x,25)^rol(x,14)^(x>>3))
 #define S1(x) (rol(x,15)^rol(x,13)^(x>>10))
 #define SS0(x) (rol(x,30)^rol(x,19)^rol(x,10))
 #define SS1(x) (rol(x,26)^rol(x,21)^rol(x,7))

 #define M(I) ( tm =   S1(x[(I-2)&0x0f]) + x[(I-7)&0x0f] \
 		    + S0(x[(I-15)&0x0f]) + x[I&0x0f]    \
 	       , x[I&0x0f] = tm )

 #define R(A,B,C,D,E,F,G,H,K,M)  do { t0 = SS0(A) + F2(A,B,C); \
                                      t1 = H + SS1(E)  \
                                       + F1(E,F,G)     \
 				      + K	      \
 				      + M;	      \
 				     D += t1;  H = t0 + t1; \
 			       } while(0)

   while (words < endp)
     {
       uint32_t tm;
       uint32_t t0, t1;
       int t;
       /* FIXME: see sha1.c for a better implementation.  */
       for (t = 0; t < 16; t++)
 	{
 	  x[t] = SWAP (*words);
 	  words++;
 	}

       R( a, b, c, d, e, f, g, h, K( 0), x[ 0] );
       R( h, a, b, c, d, e, f, g, K( 1), x[ 1] );
       R( g, h, a, b, c, d, e, f, K( 2), x[ 2] );
       R( f, g, h, a, b, c, d, e, K( 3), x[ 3] );
       R( e, f, g, h, a, b, c, d, K( 4), x[ 4] );
       R( d, e, f, g, h, a, b, c, K( 5), x[ 5] );
       R( c, d, e, f, g, h, a, b, K( 6), x[ 6] );
       R( b, c, d, e, f, g, h, a, K( 7), x[ 7] );
       R( a, b, c, d, e, f, g, h, K( 8), x[ 8] );
       R( h, a, b, c, d, e, f, g, K( 9), x[ 9] );
       R( g, h, a, b, c, d, e, f, K(10), x[10] );
       R( f, g, h, a, b, c, d, e, K(11), x[11] );
       R( e, f, g, h, a, b, c, d, K(12), x[12] );
       R( d, e, f, g, h, a, b, c, K(13), x[13] );
       R( c, d, e, f, g, h, a, b, K(14), x[14] );
       R( b, c, d, e, f, g, h, a, K(15), x[15] );
       R( a, b, c, d, e, f, g, h, K(16), M(16) );
       R( h, a, b, c, d, e, f, g, K(17), M(17) );
       R( g, h, a, b, c, d, e, f, K(18), M(18) );
       R( f, g, h, a, b, c, d, e, K(19), M(19) );
       R( e, f, g, h, a, b, c, d, K(20), M(20) );
       R( d, e, f, g, h, a, b, c, K(21), M(21) );
       R( c, d, e, f, g, h, a, b, K(22), M(22) );
       R( b, c, d, e, f, g, h, a, K(23), M(23) );
       R( a, b, c, d, e, f, g, h, K(24), M(24) );
       R( h, a, b, c, d, e, f, g, K(25), M(25) );
       R( g, h, a, b, c, d, e, f, K(26), M(26) );
       R( f, g, h, a, b, c, d, e, K(27), M(27) );
       R( e, f, g, h, a, b, c, d, K(28), M(28) );
       R( d, e, f, g, h, a, b, c, K(29), M(29) );
       R( c, d, e, f, g, h, a, b, K(30), M(30) );
       R( b, c, d, e, f, g, h, a, K(31), M(31) );
       R( a, b, c, d, e, f, g, h, K(32), M(32) );
       R( h, a, b, c, d, e, f, g, K(33), M(33) );
       R( g, h, a, b, c, d, e, f, K(34), M(34) );
       R( f, g, h, a, b, c, d, e, K(35), M(35) );
       R( e, f, g, h, a, b, c, d, K(36), M(36) );
       R( d, e, f, g, h, a, b, c, K(37), M(37) );
       R( c, d, e, f, g, h, a, b, K(38), M(38) );
       R( b, c, d, e, f, g, h, a, K(39), M(39) );
       R( a, b, c, d, e, f, g, h, K(40), M(40) );
       R( h, a, b, c, d, e, f, g, K(41), M(41) );
       R( g, h, a, b, c, d, e, f, K(42), M(42) );
       R( f, g, h, a, b, c, d, e, K(43), M(43) );
       R( e, f, g, h, a, b, c, d, K(44), M(44) );
       R( d, e, f, g, h, a, b, c, K(45), M(45) );
       R( c, d, e, f, g, h, a, b, K(46), M(46) );
       R( b, c, d, e, f, g, h, a, K(47), M(47) );
       R( a, b, c, d, e, f, g, h, K(48), M(48) );
       R( h, a, b, c, d, e, f, g, K(49), M(49) );
       R( g, h, a, b, c, d, e, f, K(50), M(50) );
       R( f, g, h, a, b, c, d, e, K(51), M(51) );
       R( e, f, g, h, a, b, c, d, K(52), M(52) );
       R( d, e, f, g, h, a, b, c, K(53), M(53) );
       R( c, d, e, f, g, h, a, b, K(54), M(54) );
       R( b, c, d, e, f, g, h, a, K(55), M(55) );
       R( a, b, c, d, e, f, g, h, K(56), M(56) );
       R( h, a, b, c, d, e, f, g, K(57), M(57) );
       R( g, h, a, b, c, d, e, f, K(58), M(58) );
       R( f, g, h, a, b, c, d, e, K(59), M(59) );
       R( e, f, g, h, a, b, c, d, K(60), M(60) );
       R( d, e, f, g, h, a, b, c, K(61), M(61) );
       R( c, d, e, f, g, h, a, b, K(62), M(62) );
       R( b, c, d, e, f, g, h, a, K(63), M(63) );

       a = ctx->state[0] += a;
       b = ctx->state[1] += b;
       c = ctx->state[2] += c;
       d = ctx->state[3] += d;
       e = ctx->state[4] += e;
       f = ctx->state[5] += f;
       g = ctx->state[6] += g;
       h = ctx->state[7] += h;
     }
 }
 #ifdef __cplusplus
 }
 #endif
	/*
	* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with
	* this work for additional information regarding copyright ownership.
	* The ASF licenses this file to You under the Apache License, Version 2.0
	* (the "License"); you may not use this file except in compliance with
	* the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include "sha256.h"

	#include <stddef.h>
	#include <string.h>

	#if USE_UNLOCKED_IO
	# include "unlocked-io.h"
	#endif

	#ifdef __cplusplus
	namespace rocketmqSignature {
	#endif

	#ifdef WORDS_BIGENDIAN
	# define SWAP(n) (n)
	#else
	# define SWAP(n) \
	(((n) << 24) \| (((n) & 0xff00) << 8) \| (((n) >> 8) & 0xff00) \| ((n) >> 24))
	#endif

	#define BLOCKSIZE 4096
	#if BLOCKSIZE % 64 != 0
	# error "invalid BLOCKSIZE"
	#endif

	/* This array contains the bytes used to pad the buffer to the next
	64-byte boundary. */
	static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ... */ };


	/*
	Takes a pointer to a 256 bit block of data (eight 32 bit ints) and
	intializes it to the start constants of the SHA256 algorithm. This
	must be called before using hash in the call to sha256_hash
	*/
	void
	sha256_init_ctx (struct sha256_ctx *ctx)
	{
	ctx->state[0] = 0x6a09e667UL;
	ctx->state[1] = 0xbb67ae85UL;
	ctx->state[2] = 0x3c6ef372UL;
	ctx->state[3] = 0xa54ff53aUL;
	ctx->state[4] = 0x510e527fUL;
	ctx->state[5] = 0x9b05688cUL;
	ctx->state[6] = 0x1f83d9abUL;
	ctx->state[7] = 0x5be0cd19UL;

	ctx->total[0] = ctx->total[1] = 0;
	ctx->buflen = 0;
	}

	void
	sha224_init_ctx (struct sha256_ctx *ctx)
	{
	ctx->state[0] = 0xc1059ed8UL;
	ctx->state[1] = 0x367cd507UL;
	ctx->state[2] = 0x3070dd17UL;
	ctx->state[3] = 0xf70e5939UL;
	ctx->state[4] = 0xffc00b31UL;
	ctx->state[5] = 0x68581511UL;
	ctx->state[6] = 0x64f98fa7UL;
	ctx->state[7] = 0xbefa4fa4UL;

	ctx->total[0] = ctx->total[1] = 0;
	ctx->buflen = 0;
	}

	/* Copy the value from v into the memory location pointed to by *cp,
	If your architecture allows unaligned access this is equivalent to
	* (uint32_t ) cp = v /
	#ifdef WIN32
	static _inline void
	#else
	static __inline__ void
	#endif
	set_uint32 (char *cp, uint32_t v)
	{
	memcpy (cp, &v, sizeof v);
	}

	/* Put result from CTX in first 32 bytes following RESBUF. The result
	must be in little endian byte order. */
	void *
	sha256_read_ctx (const struct sha256_ctx ctx, void resbuf)
	{
	int i;
	char r = (char)resbuf;

	for (i = 0; i < 8; i++)
	set_uint32 (r + i * sizeof ctx->state[0], SWAP (ctx->state[i]));

	return resbuf;
	}

	void *
	sha224_read_ctx (const struct sha256_ctx ctx, void resbuf)
	{
	int i;
	char r = (char)resbuf;

	for (i = 0; i < 7; i++)
	set_uint32 (r + i * sizeof ctx->state[0], SWAP (ctx->state[i]));

	return resbuf;
	}

	/* Process the remaining bytes in the internal buffer and the usual
	prolog according to the standard and write the result to RESBUF. */
	static void
	sha256_conclude_ctx (struct sha256_ctx *ctx)
	{
	/* Take yet unprocessed bytes into account. */
	size_t bytes = ctx->buflen;
	size_t size = (bytes < 56) ? 64 / 4 : 64 * 2 / 4;

	/* Now count remaining bytes. */
	ctx->total[0] += bytes;
	if (ctx->total[0] < bytes)
	++ctx->total[1];

	/* Put the 64-bit file length in bits at the end of the buffer.
	Use set_uint32 rather than a simple assignment, to avoid risk of
	unaligned access. */
	set_uint32 ((char *) &ctx->buffer[size - 2],
	SWAP ((ctx->total[1] << 3) \| (ctx->total[0] >> 29)));
	set_uint32 ((char *) &ctx->buffer[size - 1],
	SWAP (ctx->total[0] << 3));

	memcpy (&((char ) ctx->buffer)[bytes], fillbuf, (size - 2) 4 - bytes);

	/* Process last bytes. */
	sha256_process_block (ctx->buffer, size * 4, ctx);
	}

	void *
	sha256_finish_ctx (struct sha256_ctx ctx, void resbuf)
	{
	sha256_conclude_ctx (ctx);
	return sha256_read_ctx (ctx, resbuf);
	}

	void *
	sha224_finish_ctx (struct sha256_ctx ctx, void resbuf)
	{
	sha256_conclude_ctx (ctx);
	return sha224_read_ctx (ctx, resbuf);
	}

	/* Compute SHA256 message digest for bytes read from STREAM. The
	resulting message digest number will be written into the 32 bytes
	beginning at RESBLOCK. */
	int
	sha256_stream (FILE stream, void resblock)
	{
	struct sha256_ctx ctx;
	char buffer[BLOCKSIZE + 72];
	size_t sum;

	/* Initialize the computation context. */
	sha256_init_ctx (&ctx);

	/* Iterate over full file contents. */
	while (1)
	{
	/* We read the file in blocks of BLOCKSIZE bytes. One call of the
	computation function processes the whole buffer so that with the
	next round of the loop another block can be read. */
	size_t n;
	sum = 0;

	/* Read block. Take care for partial reads. */
	while (1)
	{
	n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);

	sum += n;

	if (sum == BLOCKSIZE)
	break;

	if (n == 0)
	{
	/* Check for the error flag IFF N == 0, so that we don't
	exit the loop after a partial read due to e.g., EAGAIN
	or EWOULDBLOCK. */
	if (ferror (stream))
	return 1;
	goto process_partial_block;
	}

	/* We've read at least one byte, so ignore errors. But always
	check for EOF, since feof may be true even though N > 0.
	Otherwise, we could end up calling fread after EOF. */
	if (feof (stream))
	goto process_partial_block;
	}

	/* Process buffer with BLOCKSIZE bytes. Note that
	BLOCKSIZE % 64 == 0
	*/
	sha256_process_block (buffer, BLOCKSIZE, &ctx);
	}

	process_partial_block:;

	/* Process any remaining bytes. */
	if (sum > 0)
	sha256_process_bytes (buffer, sum, &ctx);

	/* Construct result in desired memory. */
	sha256_finish_ctx (&ctx, resblock);
	return 0;
	}

	/* FIXME: Avoid code duplication */
	int
	sha224_stream (FILE stream, void resblock)
	{
	struct sha256_ctx ctx;
	char buffer[BLOCKSIZE + 72];
	size_t sum;

	/* Initialize the computation context. */
	sha224_init_ctx (&ctx);

	/* Iterate over full file contents. */
	while (1)
	{
	/* We read the file in blocks of BLOCKSIZE bytes. One call of the
	computation function processes the whole buffer so that with the
	next round of the loop another block can be read. */
	size_t n;
	sum = 0;

	/* Read block. Take care for partial reads. */
	while (1)
	{
	n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);

	sum += n;

	if (sum == BLOCKSIZE)
	break;

	if (n == 0)
	{
	/* Check for the error flag IFF N == 0, so that we don't
	exit the loop after a partial read due to e.g., EAGAIN
	or EWOULDBLOCK. */
	if (ferror (stream))
	return 1;
	goto process_partial_block;
	}

	/* We've read at least one byte, so ignore errors. But always
	check for EOF, since feof may be true even though N > 0.
	Otherwise, we could end up calling fread after EOF. */
	if (feof (stream))
	goto process_partial_block;
	}

	/* Process buffer with BLOCKSIZE bytes. Note that
	BLOCKSIZE % 64 == 0
	*/
	sha256_process_block (buffer, BLOCKSIZE, &ctx);
	}

	process_partial_block:;

	/* Process any remaining bytes. */
	if (sum > 0)
	sha256_process_bytes (buffer, sum, &ctx);

	/* Construct result in desired memory. */
	sha224_finish_ctx (&ctx, resblock);
	return 0;
	}

	/* Compute SHA512 message digest for LEN bytes beginning at BUFFER. The
	result is always in little endian byte order, so that a byte-wise
	output yields to the wanted ASCII representation of the message
	digest. */
	void *
	sha256_buffer (const char buffer, size_t len, void resblock)
	{
	struct sha256_ctx ctx;

	/* Initialize the computation context. */
	sha256_init_ctx (&ctx);

	/* Process whole buffer but last len % 64 bytes. */
	sha256_process_bytes (buffer, len, &ctx);

	/* Put result in desired memory area. */
	return sha256_finish_ctx (&ctx, resblock);
	}

	void *
	sha224_buffer (const char buffer, size_t len, void resblock)
	{
	struct sha256_ctx ctx;

	/* Initialize the computation context. */
	sha224_init_ctx (&ctx);

	/* Process whole buffer but last len % 64 bytes. */
	sha256_process_bytes (buffer, len, &ctx);

	/* Put result in desired memory area. */
	return sha224_finish_ctx (&ctx, resblock);
	}

	void
	sha256_process_bytes (const void buffer, size_t len, struct sha256_ctx ctx)
	{
	/* When we already have some bits in our internal buffer concatenate
	both inputs first. */
	if (ctx->buflen != 0)
	{
	size_t left_over = ctx->buflen;
	size_t add = 128 - left_over > len ? len : 128 - left_over;

	memcpy (&((char *) ctx->buffer)[left_over], buffer, add);
	ctx->buflen += add;

	if (ctx->buflen > 64)
	{
	sha256_process_block (ctx->buffer, ctx->buflen & ~63, ctx);

	ctx->buflen &= 63;
	/* The regions in the following copy operation cannot overlap. */
	memcpy (ctx->buffer,
	&((char *) ctx->buffer)[(left_over + add) & ~63],
	ctx->buflen);
	}

	buffer = (const char *) buffer + add;
	len -= add;
	}

	/* Process available complete blocks. */
	if (len >= 64)
	{
	#if !_STRING_ARCH_unaligned
	# define alignof(type) offsetof (struct { char c; type x; }, x)
	# define UNALIGNED_P(p) (((size_t) p) % alignof (uint32_t) != 0)
	if (UNALIGNED_P (buffer))
	while (len > 64)
	{
	sha256_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
	buffer = (const char *) buffer + 64;
	len -= 64;
	}
	else
	#endif
	{
	sha256_process_block (buffer, len & ~63, ctx);
	buffer = (const char *) buffer + (len & ~63);
	len &= 63;
	}
	}

	/* Move remaining bytes in internal buffer. */
	if (len > 0)
	{
	size_t left_over = ctx->buflen;

	memcpy (&((char *) ctx->buffer)[left_over], buffer, len);
	left_over += len;
	if (left_over >= 64)
	{
	sha256_process_block (ctx->buffer, 64, ctx);
	left_over -= 64;
	memcpy (ctx->buffer, &ctx->buffer[16], left_over);
	}
	ctx->buflen = left_over;
	}
	}

	/* --- Code below is the primary difference between sha1.c and sha256.c --- */

	/* SHA256 round constants */
	#define K(I) sha256_round_constants[I]
	static const uint32_t sha256_round_constants[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,
	};

	/* Round functions. */
	#define F2(A,B,C) ( ( A & B ) \| ( C & ( A \| B ) ) )
	#define F1(E,F,G) ( G ^ ( E & ( F ^ G ) ) )

	/* Process LEN bytes of BUFFER, accumulating context into CTX.
	It is assumed that LEN % 64 == 0.
	Most of this code comes from GnuPG's cipher/sha1.c. */

	void
	sha256_process_block (const void buffer, size_t len, struct sha256_ctx ctx)
	{
	const uint32_t words = (const uint32_t )buffer;
	size_t nwords = len / sizeof (uint32_t);
	const uint32_t *endp = words + nwords;
	uint32_t x[16];
	uint32_t a = ctx->state[0];
	uint32_t b = ctx->state[1];
	uint32_t c = ctx->state[2];
	uint32_t d = ctx->state[3];
	uint32_t e = ctx->state[4];
	uint32_t f = ctx->state[5];
	uint32_t g = ctx->state[6];
	uint32_t h = ctx->state[7];

	/* First increment the byte count. FIPS PUB 180-2 specifies the possible
	length of the file up to 2^64 bits. Here we only compute the
	number of bytes. Do a double word increment. */
	ctx->total[0] += len;
	if (ctx->total[0] < len)
	++ctx->total[1];

	#define rol(x, n) (((x) << (n)) \| ((x) >> (32 - (n))))
	#define S0(x) (rol(x,25)^rol(x,14)^(x>>3))
	#define S1(x) (rol(x,15)^rol(x,13)^(x>>10))
	#define SS0(x) (rol(x,30)^rol(x,19)^rol(x,10))
	#define SS1(x) (rol(x,26)^rol(x,21)^rol(x,7))

	#define M(I) ( tm = S1(x[(I-2)&0x0f]) + x[(I-7)&0x0f] \
	+ S0(x[(I-15)&0x0f]) + x[I&0x0f] \
	, x[I&0x0f] = tm )

	#define R(A,B,C,D,E,F,G,H,K,M) do { t0 = SS0(A) + F2(A,B,C); \
	t1 = H + SS1(E) \
	+ F1(E,F,G) \
	+ K \
	+ M; \
	D += t1; H = t0 + t1; \
	} while(0)

	while (words < endp)
	{
	uint32_t tm;
	uint32_t t0, t1;
	int t;
	/* FIXME: see sha1.c for a better implementation. */
	for (t = 0; t < 16; t++)
	{
	x[t] = SWAP (*words);
	words++;
	}

	R( a, b, c, d, e, f, g, h, K( 0), x[ 0] );
	R( h, a, b, c, d, e, f, g, K( 1), x[ 1] );
	R( g, h, a, b, c, d, e, f, K( 2), x[ 2] );
	R( f, g, h, a, b, c, d, e, K( 3), x[ 3] );
	R( e, f, g, h, a, b, c, d, K( 4), x[ 4] );
	R( d, e, f, g, h, a, b, c, K( 5), x[ 5] );
	R( c, d, e, f, g, h, a, b, K( 6), x[ 6] );
	R( b, c, d, e, f, g, h, a, K( 7), x[ 7] );
	R( a, b, c, d, e, f, g, h, K( 8), x[ 8] );
	R( h, a, b, c, d, e, f, g, K( 9), x[ 9] );
	R( g, h, a, b, c, d, e, f, K(10), x[10] );
	R( f, g, h, a, b, c, d, e, K(11), x[11] );
	R( e, f, g, h, a, b, c, d, K(12), x[12] );
	R( d, e, f, g, h, a, b, c, K(13), x[13] );
	R( c, d, e, f, g, h, a, b, K(14), x[14] );
	R( b, c, d, e, f, g, h, a, K(15), x[15] );
	R( a, b, c, d, e, f, g, h, K(16), M(16) );
	R( h, a, b, c, d, e, f, g, K(17), M(17) );
	R( g, h, a, b, c, d, e, f, K(18), M(18) );
	R( f, g, h, a, b, c, d, e, K(19), M(19) );
	R( e, f, g, h, a, b, c, d, K(20), M(20) );
	R( d, e, f, g, h, a, b, c, K(21), M(21) );
	R( c, d, e, f, g, h, a, b, K(22), M(22) );
	R( b, c, d, e, f, g, h, a, K(23), M(23) );
	R( a, b, c, d, e, f, g, h, K(24), M(24) );
	R( h, a, b, c, d, e, f, g, K(25), M(25) );
	R( g, h, a, b, c, d, e, f, K(26), M(26) );
	R( f, g, h, a, b, c, d, e, K(27), M(27) );
	R( e, f, g, h, a, b, c, d, K(28), M(28) );
	R( d, e, f, g, h, a, b, c, K(29), M(29) );
	R( c, d, e, f, g, h, a, b, K(30), M(30) );
	R( b, c, d, e, f, g, h, a, K(31), M(31) );
	R( a, b, c, d, e, f, g, h, K(32), M(32) );
	R( h, a, b, c, d, e, f, g, K(33), M(33) );
	R( g, h, a, b, c, d, e, f, K(34), M(34) );
	R( f, g, h, a, b, c, d, e, K(35), M(35) );
	R( e, f, g, h, a, b, c, d, K(36), M(36) );
	R( d, e, f, g, h, a, b, c, K(37), M(37) );
	R( c, d, e, f, g, h, a, b, K(38), M(38) );
	R( b, c, d, e, f, g, h, a, K(39), M(39) );
	R( a, b, c, d, e, f, g, h, K(40), M(40) );
	R( h, a, b, c, d, e, f, g, K(41), M(41) );
	R( g, h, a, b, c, d, e, f, K(42), M(42) );
	R( f, g, h, a, b, c, d, e, K(43), M(43) );
	R( e, f, g, h, a, b, c, d, K(44), M(44) );
	R( d, e, f, g, h, a, b, c, K(45), M(45) );
	R( c, d, e, f, g, h, a, b, K(46), M(46) );
	R( b, c, d, e, f, g, h, a, K(47), M(47) );
	R( a, b, c, d, e, f, g, h, K(48), M(48) );
	R( h, a, b, c, d, e, f, g, K(49), M(49) );
	R( g, h, a, b, c, d, e, f, K(50), M(50) );
	R( f, g, h, a, b, c, d, e, K(51), M(51) );
	R( e, f, g, h, a, b, c, d, K(52), M(52) );
	R( d, e, f, g, h, a, b, c, K(53), M(53) );
	R( c, d, e, f, g, h, a, b, K(54), M(54) );
	R( b, c, d, e, f, g, h, a, K(55), M(55) );
	R( a, b, c, d, e, f, g, h, K(56), M(56) );
	R( h, a, b, c, d, e, f, g, K(57), M(57) );
	R( g, h, a, b, c, d, e, f, K(58), M(58) );
	R( f, g, h, a, b, c, d, e, K(59), M(59) );
	R( e, f, g, h, a, b, c, d, K(60), M(60) );
	R( d, e, f, g, h, a, b, c, K(61), M(61) );
	R( c, d, e, f, g, h, a, b, K(62), M(62) );
	R( b, c, d, e, f, g, h, a, K(63), M(63) );

	a = ctx->state[0] += a;
	b = ctx->state[1] += b;
	c = ctx->state[2] += c;
	d = ctx->state[3] += d;
	e = ctx->state[4] += e;
	f = ctx->state[5] += f;
	g = ctx->state[6] += g;
	h = ctx->state[7] += h;
	}
	}
	#ifdef __cplusplus
	}
	#endif