md5.c revision 130561 
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.
4
5   NOTE: This source is derived from an old version taken from the GNU C
6   Library (glibc).
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
39#include "ansidecl.h"
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)  */
59static 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)  */
64void
65md5_init_ctx (ctx)
66     struct md5_ctx *ctx;
67{
68  ctx->A = (md5_uint32) 0x67452301;
69  ctx->B = (md5_uint32) 0xefcdab89;
70  ctx->C = (md5_uint32) 0x98badcfe;
71  ctx->D = (md5_uint32) 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.  */
82void *
83md5_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.  */
100void *
101md5_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.  */
131int
132md5_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.  */
188void *
189md5_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
207void
208md5_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 void *) ((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 void *) ((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
265void
266md5_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 = (const md5_uint32 *) 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, (md5_uint32) 0xd76aa478);
326      OP (D, A, B, C, 12, (md5_uint32) 0xe8c7b756);
327      OP (C, D, A, B, 17, (md5_uint32) 0x242070db);
328      OP (B, C, D, A, 22, (md5_uint32) 0xc1bdceee);
329      OP (A, B, C, D,  7, (md5_uint32) 0xf57c0faf);
330      OP (D, A, B, C, 12, (md5_uint32) 0x4787c62a);
331      OP (C, D, A, B, 17, (md5_uint32) 0xa8304613);
332      OP (B, C, D, A, 22, (md5_uint32) 0xfd469501);
333      OP (A, B, C, D,  7, (md5_uint32) 0x698098d8);
334      OP (D, A, B, C, 12, (md5_uint32) 0x8b44f7af);
335      OP (C, D, A, B, 17, (md5_uint32) 0xffff5bb1);
336      OP (B, C, D, A, 22, (md5_uint32) 0x895cd7be);
337      OP (A, B, C, D,  7, (md5_uint32) 0x6b901122);
338      OP (D, A, B, C, 12, (md5_uint32) 0xfd987193);
339      OP (C, D, A, B, 17, (md5_uint32) 0xa679438e);
340      OP (B, C, D, A, 22, (md5_uint32) 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(a, b, c, d, k, s, T)						\
347      do 								\
348	{								\
349	  a += FX (b, c, d) + correct_words[k] + T;			\
350	  CYCLIC (a, s);						\
351	  a += b;							\
352	}								\
353      while (0)
354
355#define FX(b, c, d) FG (b, c, d)
356
357      /* Round 2.  */
358      OP (A, B, C, D,  1,  5, (md5_uint32) 0xf61e2562);
359      OP (D, A, B, C,  6,  9, (md5_uint32) 0xc040b340);
360      OP (C, D, A, B, 11, 14, (md5_uint32) 0x265e5a51);
361      OP (B, C, D, A,  0, 20, (md5_uint32) 0xe9b6c7aa);
362      OP (A, B, C, D,  5,  5, (md5_uint32) 0xd62f105d);
363      OP (D, A, B, C, 10,  9, (md5_uint32) 0x02441453);
364      OP (C, D, A, B, 15, 14, (md5_uint32) 0xd8a1e681);
365      OP (B, C, D, A,  4, 20, (md5_uint32) 0xe7d3fbc8);
366      OP (A, B, C, D,  9,  5, (md5_uint32) 0x21e1cde6);
367      OP (D, A, B, C, 14,  9, (md5_uint32) 0xc33707d6);
368      OP (C, D, A, B,  3, 14, (md5_uint32) 0xf4d50d87);
369      OP (B, C, D, A,  8, 20, (md5_uint32) 0x455a14ed);
370      OP (A, B, C, D, 13,  5, (md5_uint32) 0xa9e3e905);
371      OP (D, A, B, C,  2,  9, (md5_uint32) 0xfcefa3f8);
372      OP (C, D, A, B,  7, 14, (md5_uint32) 0x676f02d9);
373      OP (B, C, D, A, 12, 20, (md5_uint32) 0x8d2a4c8a);
374
375#undef FX
376#define FX(b, c, d) FH (b, c, d)
377
378      /* Round 3.  */
379      OP (A, B, C, D,  5,  4, (md5_uint32) 0xfffa3942);
380      OP (D, A, B, C,  8, 11, (md5_uint32) 0x8771f681);
381      OP (C, D, A, B, 11, 16, (md5_uint32) 0x6d9d6122);
382      OP (B, C, D, A, 14, 23, (md5_uint32) 0xfde5380c);
383      OP (A, B, C, D,  1,  4, (md5_uint32) 0xa4beea44);
384      OP (D, A, B, C,  4, 11, (md5_uint32) 0x4bdecfa9);
385      OP (C, D, A, B,  7, 16, (md5_uint32) 0xf6bb4b60);
386      OP (B, C, D, A, 10, 23, (md5_uint32) 0xbebfbc70);
387      OP (A, B, C, D, 13,  4, (md5_uint32) 0x289b7ec6);
388      OP (D, A, B, C,  0, 11, (md5_uint32) 0xeaa127fa);
389      OP (C, D, A, B,  3, 16, (md5_uint32) 0xd4ef3085);
390      OP (B, C, D, A,  6, 23, (md5_uint32) 0x04881d05);
391      OP (A, B, C, D,  9,  4, (md5_uint32) 0xd9d4d039);
392      OP (D, A, B, C, 12, 11, (md5_uint32) 0xe6db99e5);
393      OP (C, D, A, B, 15, 16, (md5_uint32) 0x1fa27cf8);
394      OP (B, C, D, A,  2, 23, (md5_uint32) 0xc4ac5665);
395
396#undef FX
397#define FX(b, c, d) FI (b, c, d)
398
399      /* Round 4.  */
400      OP (A, B, C, D,  0,  6, (md5_uint32) 0xf4292244);
401      OP (D, A, B, C,  7, 10, (md5_uint32) 0x432aff97);
402      OP (C, D, A, B, 14, 15, (md5_uint32) 0xab9423a7);
403      OP (B, C, D, A,  5, 21, (md5_uint32) 0xfc93a039);
404      OP (A, B, C, D, 12,  6, (md5_uint32) 0x655b59c3);
405      OP (D, A, B, C,  3, 10, (md5_uint32) 0x8f0ccc92);
406      OP (C, D, A, B, 10, 15, (md5_uint32) 0xffeff47d);
407      OP (B, C, D, A,  1, 21, (md5_uint32) 0x85845dd1);
408      OP (A, B, C, D,  8,  6, (md5_uint32) 0x6fa87e4f);
409      OP (D, A, B, C, 15, 10, (md5_uint32) 0xfe2ce6e0);
410      OP (C, D, A, B,  6, 15, (md5_uint32) 0xa3014314);
411      OP (B, C, D, A, 13, 21, (md5_uint32) 0x4e0811a1);
412      OP (A, B, C, D,  4,  6, (md5_uint32) 0xf7537e82);
413      OP (D, A, B, C, 11, 10, (md5_uint32) 0xbd3af235);
414      OP (C, D, A, B,  2, 15, (md5_uint32) 0x2ad7d2bb);
415      OP (B, C, D, A,  9, 21, (md5_uint32) 0xeb86d391);
416
417      /* Add the starting values of the context.  */
418      A += A_save;
419      B += B_save;
420      C += C_save;
421      D += D_save;
422    }
423
424  /* Put checksum in context given as argument.  */
425  ctx->A = A;
426  ctx->B = B;
427  ctx->C = C;
428  ctx->D = D;
429}
430