gnulib/lib/sha256.c - toolchain/make - Git at Google

 /* sha256.c - Functions to compute SHA256 and SHA224 message digest of files or
    memory blocks according to the NIST specification FIPS-180-2.

    Copyright (C) 2005-2006, 2008-2020 Free Software Foundation, Inc.

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

 /* Written by David Madore, considerably copypasting from
    Scott G. Miller's sha1.c
 */

 #include <config.h>

 #if HAVE_OPENSSL_SHA256
 # define GL_OPENSSL_INLINE _GL_EXTERN_INLINE
 #endif
 #include "sha256.h"

 #include <stdalign.h>
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>

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

 #include <byteswap.h>
 #ifdef WORDS_BIGENDIAN
 # define SWAP(n) (n)
 #else
 # define SWAP(n) bswap_32 (n)
 #endif

 #define BLOCKSIZE 32768
 #if BLOCKSIZE % 64 != 0
 # error "invalid BLOCKSIZE"
 #endif

 #if ! HAVE_OPENSSL_SHA256
 /* 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
   initializes 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
    * (__typeof__ (v) *) cp = v  */
 static void
 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 = 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 = 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);
 }
 #endif

 #ifdef GL_COMPILE_CRYPTO_STREAM

 #include "af_alg.h"

 /* Compute message digest for bytes read from STREAM using algorithm ALG.
    Write the message digest into RESBLOCK, which contains HASHLEN bytes.
    The initial and finishing operations are INIT_CTX and FINISH_CTX.
    Return zero if and only if successful.  */
 static int
 shaxxx_stream (FILE *stream, char const *alg, void *resblock,
                ssize_t hashlen, void (*init_ctx) (struct sha256_ctx *),
                void *(*finish_ctx) (struct sha256_ctx *, void *))
 {
   switch (afalg_stream (stream, alg, resblock, hashlen))
     {
     case 0: return 0;
     case -EIO: return 1;
     }

   char *buffer = malloc (BLOCKSIZE + 72);
   if (!buffer)
     return 1;

   struct sha256_ctx ctx;
   init_ctx (&ctx);
   size_t sum;

   /* 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)
         {
           /* Either process a partial fread() from this loop,
              or the fread() in afalg_stream may have gotten EOF.
              We need to avoid a subsequent fread() as EOF may
              not be sticky.  For details of such systems, see:
              https://sourceware.org/bugzilla/show_bug.cgi?id=1190  */
           if (feof (stream))
             goto process_partial_block;

           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))
                 {
                   free (buffer);
                   return 1;
                 }
               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.  */
   finish_ctx (&ctx, resblock);
   free (buffer);
   return 0;
 }

 int
 sha256_stream (FILE *stream, void *resblock)
 {
   return shaxxx_stream (stream, "sha256", resblock, SHA256_DIGEST_SIZE,
                         sha256_init_ctx, sha256_finish_ctx);
 }

 int
 sha224_stream (FILE *stream, void *resblock)
 {
   return shaxxx_stream (stream, "sha224", resblock, SHA224_DIGEST_SIZE,
                         sha224_init_ctx, sha224_finish_ctx);
 }
 #endif

 #if ! HAVE_OPENSSL_SHA256
 /* Compute SHA256 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,
              because ctx->buflen < 64 ≤ (left_over + add) & ~63.  */
           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 || _STRING_INLINE_unaligned)
 # define UNALIGNED_P(p) ((uintptr_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;
           /* The regions in the following copy operation cannot overlap,
              because 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 = 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];
   uint32_t lolen = len;

   /* 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] += lolen;
   ctx->total[1] += (len >> 31 >> 1) + (ctx->total[0] < lolen);

 #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;
     }
 }
 #endif

 /*
  * Hey Emacs!
  * Local Variables:
  * coding: utf-8
  * End:
  */
	/* sha256.c - Functions to compute SHA256 and SHA224 message digest of files or
	memory blocks according to the NIST specification FIPS-180-2.

	Copyright (C) 2005-2006, 2008-2020 Free Software Foundation, Inc.

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program. If not, see <https://www.gnu.org/licenses/>. */

	/* Written by David Madore, considerably copypasting from
	Scott G. Miller's sha1.c
	*/

	#include <config.h>

	#if HAVE_OPENSSL_SHA256
	# define GL_OPENSSL_INLINE _GL_EXTERN_INLINE
	#endif
	#include "sha256.h"

	#include <stdalign.h>
	#include <stdint.h>
	#include <stdlib.h>
	#include <string.h>

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

	#include <byteswap.h>
	#ifdef WORDS_BIGENDIAN
	# define SWAP(n) (n)
	#else
	# define SWAP(n) bswap_32 (n)
	#endif

	#define BLOCKSIZE 32768
	#if BLOCKSIZE % 64 != 0
	# error "invalid BLOCKSIZE"
	#endif

	#if ! HAVE_OPENSSL_SHA256
	/* 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
	initializes 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
	* (__typeof__ (v) ) cp = v /
	static void
	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 = 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 = 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);
	}
	#endif

	#ifdef GL_COMPILE_CRYPTO_STREAM

	#include "af_alg.h"

	/* Compute message digest for bytes read from STREAM using algorithm ALG.
	Write the message digest into RESBLOCK, which contains HASHLEN bytes.
	The initial and finishing operations are INIT_CTX and FINISH_CTX.
	Return zero if and only if successful. */
	static int
	shaxxx_stream (FILE stream, char const alg, void *resblock,
	ssize_t hashlen, void (init_ctx) (struct sha256_ctx ),
	void (finish_ctx) (struct sha256_ctx , void ))
	{
	switch (afalg_stream (stream, alg, resblock, hashlen))
	{
	case 0: return 0;
	case -EIO: return 1;
	}

	char *buffer = malloc (BLOCKSIZE + 72);
	if (!buffer)
	return 1;

	struct sha256_ctx ctx;
	init_ctx (&ctx);
	size_t sum;

	/* 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)
	{
	/* Either process a partial fread() from this loop,
	or the fread() in afalg_stream may have gotten EOF.
	We need to avoid a subsequent fread() as EOF may
	not be sticky. For details of such systems, see:
	https://sourceware.org/bugzilla/show_bug.cgi?id=1190 */
	if (feof (stream))
	goto process_partial_block;

	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))
	{
	free (buffer);
	return 1;
	}
	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. */
	finish_ctx (&ctx, resblock);
	free (buffer);
	return 0;
	}

	int
	sha256_stream (FILE stream, void resblock)
	{
	return shaxxx_stream (stream, "sha256", resblock, SHA256_DIGEST_SIZE,
	sha256_init_ctx, sha256_finish_ctx);
	}

	int
	sha224_stream (FILE stream, void resblock)
	{
	return shaxxx_stream (stream, "sha224", resblock, SHA224_DIGEST_SIZE,
	sha224_init_ctx, sha224_finish_ctx);
	}
	#endif

	#if ! HAVE_OPENSSL_SHA256
	/* Compute SHA256 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,
	because ctx->buflen < 64 ≤ (left_over + add) & ~63. */
	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 \|\| _STRING_INLINE_unaligned)
	# define UNALIGNED_P(p) ((uintptr_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;
	/* The regions in the following copy operation cannot overlap,
	because 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 = 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];
	uint32_t lolen = len;

	/* 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] += lolen;
	ctx->total[1] += (len >> 31 >> 1) + (ctx->total[0] < lolen);

	#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;
	}
	}
	#endif

	/*
	* Hey Emacs!
	* Local Variables:
	* coding: utf-8
	* End:
	*/