Adding sha256.[ch]

Sorry forgot adding them.
Thanks for Graham Gower <graham.gower@gmail.com>

git-svn-id: http://opkg.googlecode.com/svn/trunk@223 e8e0d7a0-c8d9-11dd-a880-a1081c7ac358

2 files changed, 645 insertions, 0 deletions

diff --git a/libopkg/sha256.c b/libopkg/sha256.c
new file mode 100644
index 0000000..0ad9444
--- /dev/null
+++ b/libopkg/sha256.c
@@ -0,0 +1,554 @@
+/* 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 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 <http://www.gnu.org/licenses/>.  */
+
+/* Written by David Madore, considerably copypasting from
+   Scott G. Miller's sha1.c
+*/
+
+#include <config.h>
+
+#include "sha256.h"
+
+#include <stddef.h>
+#include <string.h>
+
+#if USE_UNLOCKED_IO
+# include "unlocked-io.h"
+#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  */
+static inline 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);
+}
+
+/* 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 = 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;
+    }
+}
diff --git a/libopkg/sha256.h b/libopkg/sha256.h
new file mode 100644
index 0000000..6a9aed4
--- /dev/null
+++ b/libopkg/sha256.h
@@ -0,0 +1,91 @@
+/* Declarations of functions and data types used for SHA256 and SHA224 sum
+   library functions.
+   Copyright (C) 2005, 2006, 2008, 2009 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 <http://www.gnu.org/licenses/>.  */
+
+#ifndef SHA256_H
+# define SHA256_H 1
+
+# include <stdio.h>
+# include <stdint.h>
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+/* Structure to save state of computation between the single steps.  */
+struct sha256_ctx
+{
+  uint32_t state[8];
+
+  uint32_t total[2];
+  size_t buflen;
+  uint32_t buffer[32];
+};
+
+enum { SHA224_DIGEST_SIZE = 224 / 8 };
+enum { SHA256_DIGEST_SIZE = 256 / 8 };
+
+/* Initialize structure containing state of computation. */
+extern void sha256_init_ctx (struct sha256_ctx *ctx);
+extern void sha224_init_ctx (struct sha256_ctx *ctx);
+
+/* Starting with the result of former calls of this function (or the
+   initialization function update the context for the next LEN bytes
+   starting at BUFFER.
+   It is necessary that LEN is a multiple of 64!!! */
+extern void sha256_process_block (const void *buffer, size_t len,
+				  struct sha256_ctx *ctx);
+
+/* Starting with the result of former calls of this function (or the
+   initialization function update the context for the next LEN bytes
+   starting at BUFFER.
+   It is NOT required that LEN is a multiple of 64.  */
+extern void sha256_process_bytes (const void *buffer, size_t len,
+				  struct sha256_ctx *ctx);
+
+/* Process the remaining bytes in the buffer and put result from CTX
+   in first 32 (28) bytes following RESBUF.  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.  */
+extern void *sha256_finish_ctx (struct sha256_ctx *ctx, void *resbuf);
+extern void *sha224_finish_ctx (struct sha256_ctx *ctx, void *resbuf);
+
+
+/* Put result from CTX in first 32 (28) bytes following RESBUF.  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.  */
+extern void *sha256_read_ctx (const struct sha256_ctx *ctx, void *resbuf);
+extern void *sha224_read_ctx (const struct sha256_ctx *ctx, void *resbuf);
+
+
+/* Compute SHA256 (SHA224) message digest for bytes read from STREAM.  The
+   resulting message digest number will be written into the 32 (28) bytes
+   beginning at RESBLOCK.  */
+extern int sha256_stream (FILE *stream, void *resblock);
+extern int sha224_stream (FILE *stream, void *resblock);
+
+/* Compute SHA256 (SHA224) 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.  */
+extern void *sha256_buffer (const char *buffer, size_t len, void *resblock);
+extern void *sha224_buffer (const char *buffer, size_t len, void *resblock);
+
+# ifdef __cplusplus
+}
+# endif
+
+#endif