[deliverable/binutils-gdb.git] / libiberty / md5.c

/* md5.c - Functions to compute MD5 message digest of files or memory blocks
   according to the definition of MD5 in RFC 1321 from April 1992.
   Copyright (C) 1995, 1996 Free Software Foundation, Inc.

   NOTE: This source is derived from an old version taken from the GNU C
   Library (glibc).

   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 2, 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, write to the Free Software Foundation,
   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

/* Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.  */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <sys/types.h>

#if STDC_HEADERS || defined _LIBC
# include <stdlib.h>
# include <string.h>
#else
# ifndef HAVE_MEMCPY
#  define memcpy(d, s, n) bcopy ((s), (d), (n))
# endif
#endif

#include "ansidecl.h"
#include "md5.h"

#ifdef _LIBC
# include <endian.h>
# if __BYTE_ORDER == __BIG_ENDIAN
#  define WORDS_BIGENDIAN 1
# endif
#endif

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


/* This array contains the bytes used to pad the buffer to the next
   64-byte boundary.  (RFC 1321, 3.1: Step 1)  */
static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */ };


/* Initialize structure containing state of computation.
   (RFC 1321, 3.3: Step 3)  */
void
md5_init_ctx (ctx)
     struct md5_ctx *ctx;
{
  ctx->A = 0x67452301;
  ctx->B = 0xefcdab89;
  ctx->C = 0x98badcfe;
  ctx->D = 0x10325476;

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

/* Put result from CTX in first 16 bytes following RESBUF.  The result
   must be in little endian byte order.

   IMPORTANT: On some systems it is required that RESBUF is correctly
   aligned for a 32 bits value.  */
void *
md5_read_ctx (ctx, resbuf)
     const struct md5_ctx *ctx;
     void *resbuf;
{
  ((md5_uint32 *) resbuf)[0] = SWAP (ctx->A);
  ((md5_uint32 *) resbuf)[1] = SWAP (ctx->B);
  ((md5_uint32 *) resbuf)[2] = SWAP (ctx->C);
  ((md5_uint32 *) resbuf)[3] = SWAP (ctx->D);

  return resbuf;
}

/* Process the remaining bytes in the internal buffer and the usual
   prolog according to the standard and write the result to RESBUF.

   IMPORTANT: On some systems it is required that RESBUF is correctly
   aligned for a 32 bits value.  */
void *
md5_finish_ctx (ctx, resbuf)
     struct md5_ctx *ctx;
     void *resbuf;
{
  /* Take yet unprocessed bytes into account.  */
  md5_uint32 bytes = ctx->buflen;
  size_t pad;

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

  pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
  memcpy (&ctx->buffer[bytes], fillbuf, pad);

  /* Put the 64-bit file length in *bits* at the end of the buffer.  */
  *(md5_uint32 *) &ctx->buffer[bytes + pad] = SWAP (ctx->total[0] << 3);
  *(md5_uint32 *) &ctx->buffer[bytes + pad + 4] = SWAP ((ctx->total[1] << 3) |
							(ctx->total[0] >> 29));

  /* Process last bytes.  */
  md5_process_block (ctx->buffer, bytes + pad + 8, ctx);

  return md5_read_ctx (ctx, resbuf);
}

/* Compute MD5 message digest for bytes read from STREAM.  The
   resulting message digest number will be written into the 16 bytes
   beginning at RESBLOCK.  */
int
md5_stream (stream, resblock)
     FILE *stream;
     void *resblock;
{
  /* Important: BLOCKSIZE must be a multiple of 64.  */
#define BLOCKSIZE 4096
  struct md5_ctx ctx;
  char buffer[BLOCKSIZE + 72];
  size_t sum;

  /* Initialize the computation context.  */
  md5_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.  */
      do
	{
	  n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);

	  sum += n;
	}
      while (sum < BLOCKSIZE && n != 0);
      if (n == 0 && ferror (stream))
        return 1;

      /* If end of file is reached, end the loop.  */
      if (n == 0)
	break;

      /* Process buffer with BLOCKSIZE bytes.  Note that
			BLOCKSIZE % 64 == 0
       */
      md5_process_block (buffer, BLOCKSIZE, &ctx);
    }

  /* Add the last bytes if necessary.  */
  if (sum > 0)
    md5_process_bytes (buffer, sum, &ctx);

  /* Construct result in desired memory.  */
  md5_finish_ctx (&ctx, resblock);
  return 0;
}

/* Compute MD5 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 *
md5_buffer (buffer, len, resblock)
     const char *buffer;
     size_t len;
     void *resblock;
{
  struct md5_ctx ctx;

  /* Initialize the computation context.  */
  md5_init_ctx (&ctx);

  /* Process whole buffer but last len % 64 bytes.  */
  md5_process_bytes (buffer, len, &ctx);

  /* Put result in desired memory area.  */
  return md5_finish_ctx (&ctx, resblock);
}


void
md5_process_bytes (buffer, len, ctx)
     const void *buffer;
     size_t len;
     struct md5_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 (&ctx->buffer[left_over], buffer, add);
      ctx->buflen += add;

      if (left_over + add > 64)
	{
	  md5_process_block (ctx->buffer, (left_over + add) & ~63, ctx);
	  /* The regions in the following copy operation cannot overlap.  */
	  memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
		  (left_over + add) & 63);
	  ctx->buflen = (left_over + add) & 63;
	}

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

  /* Process available complete blocks.  */
  if (len > 64)
    {
      md5_process_block (buffer, len & ~63, ctx);
      buffer = (const char *) buffer + (len & ~63);
      len &= 63;
    }

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


/* These are the four functions used in the four steps of the MD5 algorithm
   and defined in the RFC 1321.  The first function is a little bit optimized
   (as found in Colin Plumbs public domain implementation).  */
/* #define FF(b, c, d) ((b & c) | (~b & d)) */
#define FF(b, c, d) (d ^ (b & (c ^ d)))
#define FG(b, c, d) FF (d, b, c)
#define FH(b, c, d) (b ^ c ^ d)
#define FI(b, c, d) (c ^ (b | ~d))

/* Process LEN bytes of BUFFER, accumulating context into CTX.
   It is assumed that LEN % 64 == 0.  */

void
md5_process_block (buffer, len, ctx)
     const void *buffer;
     size_t len;
     struct md5_ctx *ctx;
{
  md5_uint32 correct_words[16];
  const md5_uint32 *words = buffer;
  size_t nwords = len / sizeof (md5_uint32);
  const md5_uint32 *endp = words + nwords;
  md5_uint32 A = ctx->A;
  md5_uint32 B = ctx->B;
  md5_uint32 C = ctx->C;
  md5_uint32 D = ctx->D;

  /* First increment the byte count.  RFC 1321 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];

  /* Process all bytes in the buffer with 64 bytes in each round of
     the loop.  */
  while (words < endp)
    {
      md5_uint32 *cwp = correct_words;
      md5_uint32 A_save = A;
      md5_uint32 B_save = B;
      md5_uint32 C_save = C;
      md5_uint32 D_save = D;

      /* First round: using the given function, the context and a constant
	 the next context is computed.  Because the algorithms processing
	 unit is a 32-bit word and it is determined to work on words in
	 little endian byte order we perhaps have to change the byte order
	 before the computation.  To reduce the work for the next steps
	 we store the swapped words in the array CORRECT_WORDS.  */

#define OP(a, b, c, d, s, T)						\
      do								\
        {								\
	  a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T;		\
	  ++words;							\
	  CYCLIC (a, s);						\
	  a += b;							\
        }								\
      while (0)

      /* It is unfortunate that C does not provide an operator for
	 cyclic rotation.  Hope the C compiler is smart enough.  */
#define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s)))

      /* Before we start, one word to the strange constants.
	 They are defined in RFC 1321 as

	 T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64
       */

      /* Round 1.  */
      OP (A, B, C, D,  7, 0xd76aa478);
      OP (D, A, B, C, 12, 0xe8c7b756);
      OP (C, D, A, B, 17, 0x242070db);
      OP (B, C, D, A, 22, 0xc1bdceee);
      OP (A, B, C, D,  7, 0xf57c0faf);
      OP (D, A, B, C, 12, 0x4787c62a);
      OP (C, D, A, B, 17, 0xa8304613);
      OP (B, C, D, A, 22, 0xfd469501);
      OP (A, B, C, D,  7, 0x698098d8);
      OP (D, A, B, C, 12, 0x8b44f7af);
      OP (C, D, A, B, 17, 0xffff5bb1);
      OP (B, C, D, A, 22, 0x895cd7be);
      OP (A, B, C, D,  7, 0x6b901122);
      OP (D, A, B, C, 12, 0xfd987193);
      OP (C, D, A, B, 17, 0xa679438e);
      OP (B, C, D, A, 22, 0x49b40821);

      /* For the second to fourth round we have the possibly swapped words
	 in CORRECT_WORDS.  Redefine the macro to take an additional first
	 argument specifying the function to use.  */
#undef OP
#define OP(f, a, b, c, d, k, s, T)					\
      do 								\
	{								\
	  a += f (b, c, d) + correct_words[k] + T;			\
	  CYCLIC (a, s);						\
	  a += b;							\
	}								\
      while (0)

      /* Round 2.  */
      OP (FG, A, B, C, D,  1,  5, 0xf61e2562);
      OP (FG, D, A, B, C,  6,  9, 0xc040b340);
      OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
      OP (FG, B, C, D, A,  0, 20, 0xe9b6c7aa);
      OP (FG, A, B, C, D,  5,  5, 0xd62f105d);
      OP (FG, D, A, B, C, 10,  9, 0x02441453);
      OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
      OP (FG, B, C, D, A,  4, 20, 0xe7d3fbc8);
      OP (FG, A, B, C, D,  9,  5, 0x21e1cde6);
      OP (FG, D, A, B, C, 14,  9, 0xc33707d6);
      OP (FG, C, D, A, B,  3, 14, 0xf4d50d87);
      OP (FG, B, C, D, A,  8, 20, 0x455a14ed);
      OP (FG, A, B, C, D, 13,  5, 0xa9e3e905);
      OP (FG, D, A, B, C,  2,  9, 0xfcefa3f8);
      OP (FG, C, D, A, B,  7, 14, 0x676f02d9);
      OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);

      /* Round 3.  */
      OP (FH, A, B, C, D,  5,  4, 0xfffa3942);
      OP (FH, D, A, B, C,  8, 11, 0x8771f681);
      OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
      OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
      OP (FH, A, B, C, D,  1,  4, 0xa4beea44);
      OP (FH, D, A, B, C,  4, 11, 0x4bdecfa9);
      OP (FH, C, D, A, B,  7, 16, 0xf6bb4b60);
      OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
      OP (FH, A, B, C, D, 13,  4, 0x289b7ec6);
      OP (FH, D, A, B, C,  0, 11, 0xeaa127fa);
      OP (FH, C, D, A, B,  3, 16, 0xd4ef3085);
      OP (FH, B, C, D, A,  6, 23, 0x04881d05);
      OP (FH, A, B, C, D,  9,  4, 0xd9d4d039);
      OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
      OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
      OP (FH, B, C, D, A,  2, 23, 0xc4ac5665);

      /* Round 4.  */
      OP (FI, A, B, C, D,  0,  6, 0xf4292244);
      OP (FI, D, A, B, C,  7, 10, 0x432aff97);
      OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
      OP (FI, B, C, D, A,  5, 21, 0xfc93a039);
      OP (FI, A, B, C, D, 12,  6, 0x655b59c3);
      OP (FI, D, A, B, C,  3, 10, 0x8f0ccc92);
      OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
      OP (FI, B, C, D, A,  1, 21, 0x85845dd1);
      OP (FI, A, B, C, D,  8,  6, 0x6fa87e4f);
      OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
      OP (FI, C, D, A, B,  6, 15, 0xa3014314);
      OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
      OP (FI, A, B, C, D,  4,  6, 0xf7537e82);
      OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
      OP (FI, C, D, A, B,  2, 15, 0x2ad7d2bb);
      OP (FI, B, C, D, A,  9, 21, 0xeb86d391);

      /* Add the starting values of the context.  */
      A += A_save;
      B += B_save;
      C += C_save;
      D += D_save;
    }

  /* Put checksum in context given as argument.  */
  ctx->A = A;
  ctx->B = B;
  ctx->C = C;
  ctx->D = D;
}
Commit	Line	Data
050823ca JM	1	/* md5.c - Functions to compute MD5 message digest of files or memory blocks
	2	according to the definition of MD5 in RFC 1321 from April 1992.
	3	Copyright (C) 1995, 1996 Free Software Foundation, Inc.
f6528837 DD	4
	5	NOTE: This source is derived from an old version taken from the GNU C
	6	Library (glibc).
050823ca JM	7
	8	This program is free software; you can redistribute it and/or modify it
	9	under the terms of the GNU General Public License as published by the
	10	Free Software Foundation; either version 2, or (at your option) any
	11	later version.
	12
	13	This program is distributed in the hope that it will be useful,
	14	but WITHOUT ANY WARRANTY; without even the implied warranty of
	15	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	16	GNU General Public License for more details.
	17
	18	You should have received a copy of the GNU General Public License
	19	along with this program; if not, write to the Free Software Foundation,
	20	Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
	21
	22	/* Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995. */
	23
	24	#ifdef HAVE_CONFIG_H
	25	# include <config.h>
	26	#endif
	27
	28	#include <sys/types.h>
	29
	30	#if STDC_HEADERS \|\| defined _LIBC
	31	# include <stdlib.h>
	32	# include <string.h>
	33	#else
	34	# ifndef HAVE_MEMCPY
	35	# define memcpy(d, s, n) bcopy ((s), (d), (n))
	36	# endif
	37	#endif
	38
87263c36	39	#include "ansidecl.h"
050823ca JM	40	#include "md5.h"
	41
	42	#ifdef _LIBC
	43	# include <endian.h>
	44	# if __BYTE_ORDER == __BIG_ENDIAN
	45	# define WORDS_BIGENDIAN 1
	46	# endif
	47	#endif
	48
	49	#ifdef WORDS_BIGENDIAN
	50	# define SWAP(n) \
	51	(((n) << 24) \| (((n) & 0xff00) << 8) \| (((n) >> 8) & 0xff00) \| ((n) >> 24))
	52	#else
	53	# define SWAP(n) (n)
	54	#endif
	55
	56
	57	/* This array contains the bytes used to pad the buffer to the next
	58	64-byte boundary. (RFC 1321, 3.1: Step 1) */
	59	static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ... */ };
	60
	61
	62	/* Initialize structure containing state of computation.
	63	(RFC 1321, 3.3: Step 3) */
	64	void
	65	md5_init_ctx (ctx)
	66	struct md5_ctx *ctx;
	67	{
	68	ctx->A = 0x67452301;
	69	ctx->B = 0xefcdab89;
	70	ctx->C = 0x98badcfe;
	71	ctx->D = 0x10325476;
	72
	73	ctx->total[0] = ctx->total[1] = 0;
	74	ctx->buflen = 0;
	75	}
	76
	77	/* Put result from CTX in first 16 bytes following RESBUF. The result
	78	must be in little endian byte order.
	79
	80	IMPORTANT: On some systems it is required that RESBUF is correctly
	81	aligned for a 32 bits value. */
	82	void *
	83	md5_read_ctx (ctx, resbuf)
	84	const struct md5_ctx *ctx;
	85	void *resbuf;
	86	{
	87	((md5_uint32 *) resbuf)[0] = SWAP (ctx->A);
	88	((md5_uint32 *) resbuf)[1] = SWAP (ctx->B);
	89	((md5_uint32 *) resbuf)[2] = SWAP (ctx->C);
	90	((md5_uint32 *) resbuf)[3] = SWAP (ctx->D);
	91
	92	return resbuf;
	93	}
	94
	95	/* Process the remaining bytes in the internal buffer and the usual
	96	prolog according to the standard and write the result to RESBUF.
	97
	98	IMPORTANT: On some systems it is required that RESBUF is correctly
	99	aligned for a 32 bits value. */
	100	void *
	101	md5_finish_ctx (ctx, resbuf)
	102	struct md5_ctx *ctx;
	103	void *resbuf;
104	{
105	/* Take yet unprocessed bytes into account. */
106	md5_uint32 bytes = ctx->buflen;
107	size_t pad;
108
109	/* Now count remaining bytes. */
110	ctx->total[0] += bytes;
111	if (ctx->total[0] < bytes)
112	++ctx->total[1];
113
114	pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
115	memcpy (&ctx->buffer[bytes], fillbuf, pad);
116
117	/* Put the 64-bit file length in bits at the end of the buffer. */
118	(md5_uint32 ) &ctx->buffer[bytes + pad] = SWAP (ctx->total[0] << 3);
119	(md5_uint32 ) &ctx->buffer[bytes + pad + 4] = SWAP ((ctx->total[1] << 3) \|
120	(ctx->total[0] >> 29));
121
122	/* Process last bytes. */
123	md5_process_block (ctx->buffer, bytes + pad + 8, ctx);
124
125	return md5_read_ctx (ctx, resbuf);
126	}
127
128	/* Compute MD5 message digest for bytes read from STREAM. The
129	resulting message digest number will be written into the 16 bytes
130	beginning at RESBLOCK. */
131	int
132	md5_stream (stream, resblock)
133	FILE *stream;
134	void *resblock;
135	{
136	/* Important: BLOCKSIZE must be a multiple of 64. */
137	#define BLOCKSIZE 4096
138	struct md5_ctx ctx;
139	char buffer[BLOCKSIZE + 72];
140	size_t sum;
141
142	/* Initialize the computation context. */
143	md5_init_ctx (&ctx);
144
145	/* Iterate over full file contents. */
146	while (1)
147	{
148	/* We read the file in blocks of BLOCKSIZE bytes. One call of the
149	computation function processes the whole buffer so that with the
150	next round of the loop another block can be read. */
151	size_t n;
152	sum = 0;
153
154	/* Read block. Take care for partial reads. */
155	do
156	{
157	n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
158
159	sum += n;
160	}
161	while (sum < BLOCKSIZE && n != 0);
162	if (n == 0 && ferror (stream))
163	return 1;
164
165	/* If end of file is reached, end the loop. */
166	if (n == 0)
167	break;
168
169	/* Process buffer with BLOCKSIZE bytes. Note that
170	BLOCKSIZE % 64 == 0
171	*/
172	md5_process_block (buffer, BLOCKSIZE, &ctx);
173	}
174
175	/* Add the last bytes if necessary. */
176	if (sum > 0)
177	md5_process_bytes (buffer, sum, &ctx);
178
179	/* Construct result in desired memory. */
180	md5_finish_ctx (&ctx, resblock);
181	return 0;
182	}
183
184	/* Compute MD5 message digest for LEN bytes beginning at BUFFER. The
185	result is always in little endian byte order, so that a byte-wise
186	output yields to the wanted ASCII representation of the message
187	digest. */
188	void *
189	md5_buffer (buffer, len, resblock)
190	const char *buffer;
191	size_t len;
192	void *resblock;
193	{
194	struct md5_ctx ctx;
195
196	/* Initialize the computation context. */
197	md5_init_ctx (&ctx);
198
199	/* Process whole buffer but last len % 64 bytes. */
200	md5_process_bytes (buffer, len, &ctx);
201
202	/* Put result in desired memory area. */
203	return md5_finish_ctx (&ctx, resblock);
204	}
205
206
207	void
208	md5_process_bytes (buffer, len, ctx)
209	const void *buffer;
210	size_t len;
211	struct md5_ctx *ctx;
212	{
213	/* When we already have some bits in our internal buffer concatenate
214	both inputs first. */
215	if (ctx->buflen != 0)
216	{
217	size_t left_over = ctx->buflen;
218	size_t add = 128 - left_over > len ? len : 128 - left_over;
219
220	memcpy (&ctx->buffer[left_over], buffer, add);
221	ctx->buflen += add;
222
223	if (left_over + add > 64)
224	{
225	md5_process_block (ctx->buffer, (left_over + add) & ~63, ctx);
226	/* The regions in the following copy operation cannot overlap. */
227	memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
228	(left_over + add) & 63);
229	ctx->buflen = (left_over + add) & 63;
230	}
231
232	buffer = (const char *) buffer + add;
233	len -= add;
234	}
235
236	/* Process available complete blocks. */
237	if (len > 64)
238	{
239	md5_process_block (buffer, len & ~63, ctx);
240	buffer = (const char *) buffer + (len & ~63);
241	len &= 63;
242	}
243
244	/* Move remaining bytes in internal buffer. */
245	if (len > 0)
246	{
247	memcpy (ctx->buffer, buffer, len);
248	ctx->buflen = len;
249	}
250	}
251
252
253	/* These are the four functions used in the four steps of the MD5 algorithm
254	and defined in the RFC 1321. The first function is a little bit optimized
255	(as found in Colin Plumbs public domain implementation). */
256	/* #define FF(b, c, d) ((b & c) \| (~b & d)) */
257	#define FF(b, c, d) (d ^ (b & (c ^ d)))
258	#define FG(b, c, d) FF (d, b, c)
259	#define FH(b, c, d) (b ^ c ^ d)
260	#define FI(b, c, d) (c ^ (b \| ~d))
261
262	/* Process LEN bytes of BUFFER, accumulating context into CTX.
263	It is assumed that LEN % 64 == 0. */
264
265	void
266	md5_process_block (buffer, len, ctx)
267	const void *buffer;
268	size_t len;
269	struct md5_ctx *ctx;
270	{
271	md5_uint32 correct_words[16];
272	const md5_uint32 *words = buffer;
273	size_t nwords = len / sizeof (md5_uint32);
274	const md5_uint32 *endp = words + nwords;
275	md5_uint32 A = ctx->A;
276	md5_uint32 B = ctx->B;
277	md5_uint32 C = ctx->C;
278	md5_uint32 D = ctx->D;
279
280	/* First increment the byte count. RFC 1321 specifies the possible
281	length of the file up to 2^64 bits. Here we only compute the
282	number of bytes. Do a double word increment. */
283	ctx->total[0] += len;
284	if (ctx->total[0] < len)
285	++ctx->total[1];
286
287	/* Process all bytes in the buffer with 64 bytes in each round of
288	the loop. */
289	while (words < endp)
290	{
291	md5_uint32 *cwp = correct_words;
292	md5_uint32 A_save = A;
293	md5_uint32 B_save = B;
294	md5_uint32 C_save = C;
295	md5_uint32 D_save = D;
296
297	/* First round: using the given function, the context and a constant
298	the next context is computed. Because the algorithms processing
299	unit is a 32-bit word and it is determined to work on words in
300	little endian byte order we perhaps have to change the byte order
301	before the computation. To reduce the work for the next steps
302	we store the swapped words in the array CORRECT_WORDS. */
303
304	#define OP(a, b, c, d, s, T) \
305	do \
306	{ \
307	a += FF (b, c, d) + (cwp++ = SWAP (words)) + T; \
308	++words; \
309	CYCLIC (a, s); \
310	a += b; \
311	} \
312	while (0)
313
314	/* It is unfortunate that C does not provide an operator for
315	cyclic rotation. Hope the C compiler is smart enough. */
316	#define CYCLIC(w, s) (w = (w << s) \| (w >> (32 - s)))
317
318	/* Before we start, one word to the strange constants.
319	They are defined in RFC 1321 as
320
321	T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64
322	*/
323
324	/* Round 1. */
325	OP (A, B, C, D, 7, 0xd76aa478);
326	OP (D, A, B, C, 12, 0xe8c7b756);
327	OP (C, D, A, B, 17, 0x242070db);
328	OP (B, C, D, A, 22, 0xc1bdceee);
329	OP (A, B, C, D, 7, 0xf57c0faf);
330	OP (D, A, B, C, 12, 0x4787c62a);
331	OP (C, D, A, B, 17, 0xa8304613);
332	OP (B, C, D, A, 22, 0xfd469501);
333	OP (A, B, C, D, 7, 0x698098d8);
334	OP (D, A, B, C, 12, 0x8b44f7af);
335	OP (C, D, A, B, 17, 0xffff5bb1);
336	OP (B, C, D, A, 22, 0x895cd7be);
337	OP (A, B, C, D, 7, 0x6b901122);
338	OP (D, A, B, C, 12, 0xfd987193);
339	OP (C, D, A, B, 17, 0xa679438e);
340	OP (B, C, D, A, 22, 0x49b40821);
341
342	/* For the second to fourth round we have the possibly swapped words
343	in CORRECT_WORDS. Redefine the macro to take an additional first
344	argument specifying the function to use. */
345	#undef OP
346	#define OP(f, a, b, c, d, k, s, T) \
347	do \
348	{ \
349	a += f (b, c, d) + correct_words[k] + T; \
350	CYCLIC (a, s); \
351	a += b; \
352	} \
353	while (0)
354
355	/* Round 2. */
356	OP (FG, A, B, C, D, 1, 5, 0xf61e2562);
357	OP (FG, D, A, B, C, 6, 9, 0xc040b340);
358	OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
359	OP (FG, B, C, D, A, 0, 20, 0xe9b6c7aa);
360	OP (FG, A, B, C, D, 5, 5, 0xd62f105d);
361	OP (FG, D, A, B, C, 10, 9, 0x02441453);
362	OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
363	OP (FG, B, C, D, A, 4, 20, 0xe7d3fbc8);
364	OP (FG, A, B, C, D, 9, 5, 0x21e1cde6);
365	OP (FG, D, A, B, C, 14, 9, 0xc33707d6);
366	OP (FG, C, D, A, B, 3, 14, 0xf4d50d87);
367	OP (FG, B, C, D, A, 8, 20, 0x455a14ed);
368	OP (FG, A, B, C, D, 13, 5, 0xa9e3e905);
369	OP (FG, D, A, B, C, 2, 9, 0xfcefa3f8);
370	OP (FG, C, D, A, B, 7, 14, 0x676f02d9);
371	OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);
372
373	/* Round 3. */
374	OP (FH, A, B, C, D, 5, 4, 0xfffa3942);
375	OP (FH, D, A, B, C, 8, 11, 0x8771f681);
376	OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
377	OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
378	OP (FH, A, B, C, D, 1, 4, 0xa4beea44);
379	OP (FH, D, A, B, C, 4, 11, 0x4bdecfa9);
380	OP (FH, C, D, A, B, 7, 16, 0xf6bb4b60);
381	OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
382	OP (FH, A, B, C, D, 13, 4, 0x289b7ec6);
383	OP (FH, D, A, B, C, 0, 11, 0xeaa127fa);
384	OP (FH, C, D, A, B, 3, 16, 0xd4ef3085);
385	OP (FH, B, C, D, A, 6, 23, 0x04881d05);
386	OP (FH, A, B, C, D, 9, 4, 0xd9d4d039);
387	OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
388	OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
389	OP (FH, B, C, D, A, 2, 23, 0xc4ac5665);
390
391	/* Round 4. */
392	OP (FI, A, B, C, D, 0, 6, 0xf4292244);
393	OP (FI, D, A, B, C, 7, 10, 0x432aff97);
394	OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
395	OP (FI, B, C, D, A, 5, 21, 0xfc93a039);
396	OP (FI, A, B, C, D, 12, 6, 0x655b59c3);
397	OP (FI, D, A, B, C, 3, 10, 0x8f0ccc92);
398	OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
399	OP (FI, B, C, D, A, 1, 21, 0x85845dd1);
400	OP (FI, A, B, C, D, 8, 6, 0x6fa87e4f);
401	OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
402	OP (FI, C, D, A, B, 6, 15, 0xa3014314);
403	OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
404	OP (FI, A, B, C, D, 4, 6, 0xf7537e82);
405	OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
406	OP (FI, C, D, A, B, 2, 15, 0x2ad7d2bb);
407	OP (FI, B, C, D, A, 9, 21, 0xeb86d391);
408
409	/* Add the starting values of the context. */
410	A += A_save;
411	B += B_save;
412	C += C_save;
413	D += D_save;
414	}
415
416	/* Put checksum in context given as argument. */
417	ctx->A = A;
418	ctx->B = B;
419	ctx->C = C;
420	ctx->D = D;
421	}