1/* 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) 1995-2011 Red Hat, Inc.
4   This file is part of Red Hat elfutils.
5   Written by Ulrich Drepper <drepper@redhat.com>, 1995.
6
7   Red Hat elfutils is free software; you can redistribute it and/or modify
8   it under the terms of the GNU General Public License as published by the
9   Free Software Foundation; version 2 of the License.
10
11   Red Hat elfutils is distributed in the hope that it will be useful, but
12   WITHOUT ANY WARRANTY; without even the implied warranty of
13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14   General Public License for more details.
15
16   You should have received a copy of the GNU General Public License along
17   with Red Hat elfutils; if not, write to the Free Software Foundation,
18   Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
19
20   Red Hat elfutils is an included package of the Open Invention Network.
21   An included package of the Open Invention Network is a package for which
22   Open Invention Network licensees cross-license their patents.  No patent
23   license is granted, either expressly or impliedly, by designation as an
24   included package.  Should you wish to participate in the Open Invention
25   Network licensing program, please visit www.openinventionnetwork.com
26   <http://www.openinventionnetwork.com>.  */
27
28#ifdef HAVE_CONFIG_H
29# include <config.h>
30#endif
31
32#include <stdlib.h>
33#include <string.h>
34#include <sys/types.h>
35
36#include "md5.h"
37#include "system.h"
38
39#define SWAP(n) LE32 (n)
40
41/* This array contains the bytes used to pad the buffer to the next
42   64-byte boundary.  (RFC 1321, 3.1: Step 1)  */
43static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */ };
44
45
46/* Initialize structure containing state of computation.
47   (RFC 1321, 3.3: Step 3)  */
48void
49md5_init_ctx (ctx)
50     struct md5_ctx *ctx;
51{
52  ctx->A = 0x67452301;
53  ctx->B = 0xefcdab89;
54  ctx->C = 0x98badcfe;
55  ctx->D = 0x10325476;
56
57  ctx->total[0] = ctx->total[1] = 0;
58  ctx->buflen = 0;
59}
60
61/* Put result from CTX in first 16 bytes following RESBUF.  The result
62   must be in little endian byte order.
63
64   IMPORTANT: On some systems it is required that RESBUF is correctly
65   aligned for a 32 bits value.  */
66void *
67md5_read_ctx (ctx, resbuf)
68     const struct md5_ctx *ctx;
69     void *resbuf;
70{
71  ((md5_uint32 *) resbuf)[0] = SWAP (ctx->A);
72  ((md5_uint32 *) resbuf)[1] = SWAP (ctx->B);
73  ((md5_uint32 *) resbuf)[2] = SWAP (ctx->C);
74  ((md5_uint32 *) resbuf)[3] = SWAP (ctx->D);
75
76  return resbuf;
77}
78
79static void
80le64_copy (char *dest, uint64_t x)
81{
82  for (size_t i = 0; i < 8; ++i)
83    {
84      dest[i] = (uint8_t) x;
85      x >>= 8;
86    }
87}
88
89/* Process the remaining bytes in the internal buffer and the usual
90   prolog according to the standard and write the result to RESBUF.
91
92   IMPORTANT: On some systems it is required that RESBUF is correctly
93   aligned for a 32 bits value.  */
94void *
95md5_finish_ctx (ctx, resbuf)
96     struct md5_ctx *ctx;
97     void *resbuf;
98{
99  /* Take yet unprocessed bytes into account.  */
100  md5_uint32 bytes = ctx->buflen;
101  size_t pad;
102
103  /* Now count remaining bytes.  */
104  ctx->total[0] += bytes;
105  if (ctx->total[0] < bytes)
106    ++ctx->total[1];
107
108  pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
109  memcpy (&ctx->buffer[bytes], fillbuf, pad);
110
111  /* Put the 64-bit file length in *bits* at the end of the buffer.  */
112  const uint64_t bit_length = ((ctx->total[0] << 3)
113			       + ((uint64_t) ((ctx->total[1] << 3) |
114					      (ctx->total[0] >> 29)) << 32));
115  le64_copy (&ctx->buffer[bytes + pad], bit_length);
116
117  /* Process last bytes.  */
118  md5_process_block (ctx->buffer, bytes + pad + 8, ctx);
119
120  return md5_read_ctx (ctx, resbuf);
121}
122
123
124#ifdef NEED_MD5_STREAM
125/* Compute MD5 message digest for bytes read from STREAM.  The
126   resulting message digest number will be written into the 16 bytes
127   beginning at RESBLOCK.  */
128int
129md5_stream (stream, resblock)
130     FILE *stream;
131     void *resblock;
132{
133  /* Important: BLOCKSIZE must be a multiple of 64.  */
134#define BLOCKSIZE 4096
135  struct md5_ctx ctx;
136  char buffer[BLOCKSIZE + 72];
137  size_t sum;
138
139  /* Initialize the computation context.  */
140  md5_init_ctx (&ctx);
141
142  /* Iterate over full file contents.  */
143  while (1)
144    {
145      /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
146	 computation function processes the whole buffer so that with the
147	 next round of the loop another block can be read.  */
148      size_t n;
149      sum = 0;
150
151      /* Read block.  Take care for partial reads.  */
152      do
153	{
154	  n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
155
156	  sum += n;
157	}
158      while (sum < BLOCKSIZE && n != 0);
159      if (n == 0 && ferror (stream))
160        return 1;
161
162      /* If end of file is reached, end the loop.  */
163      if (n == 0)
164	break;
165
166      /* Process buffer with BLOCKSIZE bytes.  Note that
167			BLOCKSIZE % 64 == 0
168       */
169      md5_process_block (buffer, BLOCKSIZE, &ctx);
170    }
171
172  /* Add the last bytes if necessary.  */
173  if (sum > 0)
174    md5_process_bytes (buffer, sum, &ctx);
175
176  /* Construct result in desired memory.  */
177  md5_finish_ctx (&ctx, resblock);
178  return 0;
179}
180#endif
181
182
183#ifdef NEED_MD5_BUFFER
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#endif
206
207
208void
209md5_process_bytes (buffer, len, ctx)
210     const void *buffer;
211     size_t len;
212     struct md5_ctx *ctx;
213{
214  /* When we already have some bits in our internal buffer concatenate
215     both inputs first.  */
216  if (ctx->buflen != 0)
217    {
218      size_t left_over = ctx->buflen;
219      size_t add = 128 - left_over > len ? len : 128 - left_over;
220
221      memcpy (&ctx->buffer[left_over], buffer, add);
222      ctx->buflen += add;
223
224      if (ctx->buflen > 64)
225	{
226	  md5_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
227
228	  ctx->buflen &= 63;
229	  /* The regions in the following copy operation cannot overlap.  */
230	  memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
231		  ctx->buflen);
232	}
233
234      buffer = (const char *) buffer + add;
235      len -= add;
236    }
237
238  /* Process available complete blocks.  */
239  if (len >= 64)
240    {
241#if !_STRING_ARCH_unaligned
242/* To check alignment gcc has an appropriate operator.  Other
243   compilers don't.  */
244# if __GNUC__ >= 2
245#  define UNALIGNED_P(p) (((md5_uintptr) p) % __alignof__ (md5_uint32) != 0)
246# else
247#  define UNALIGNED_P(p) (((md5_uintptr) p) % sizeof (md5_uint32) != 0)
248# endif
249      if (UNALIGNED_P (buffer))
250	while (len > 64)
251	  {
252	    md5_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
253	    buffer = (const char *) buffer + 64;
254	    len -= 64;
255	  }
256      else
257#endif
258	{
259	  md5_process_block (buffer, len & ~63, ctx);
260	  buffer = (const char *) buffer + (len & ~63);
261	  len &= 63;
262	}
263    }
264
265  /* Move remaining bytes in internal buffer.  */
266  if (len > 0)
267    {
268      size_t left_over = ctx->buflen;
269
270      memcpy (&ctx->buffer[left_over], buffer, len);
271      left_over += len;
272      if (left_over >= 64)
273	{
274	  md5_process_block (ctx->buffer, 64, ctx);
275	  left_over -= 64;
276	  memcpy (ctx->buffer, &ctx->buffer[64], left_over);
277	}
278      ctx->buflen = left_over;
279    }
280}
281
282
283/* These are the four functions used in the four steps of the MD5 algorithm
284   and defined in the RFC 1321.  The first function is a little bit optimized
285   (as found in Colin Plumbs public domain implementation).  */
286/* #define FF(b, c, d) ((b & c) | (~b & d)) */
287#define FF(b, c, d) (d ^ (b & (c ^ d)))
288#define FG(b, c, d) FF (d, b, c)
289#define FH(b, c, d) (b ^ c ^ d)
290#define FI(b, c, d) (c ^ (b | ~d))
291
292/* Process LEN bytes of BUFFER, accumulating context into CTX.
293   It is assumed that LEN % 64 == 0.  */
294
295void
296md5_process_block (buffer, len, ctx)
297     const void *buffer;
298     size_t len;
299     struct md5_ctx *ctx;
300{
301  md5_uint32 correct_words[16];
302  const md5_uint32 *words = buffer;
303  size_t nwords = len / sizeof (md5_uint32);
304  const md5_uint32 *endp = words + nwords;
305  md5_uint32 A = ctx->A;
306  md5_uint32 B = ctx->B;
307  md5_uint32 C = ctx->C;
308  md5_uint32 D = ctx->D;
309
310  /* First increment the byte count.  RFC 1321 specifies the possible
311     length of the file up to 2^64 bits.  Here we only compute the
312     number of bytes.  Do a double word increment.  */
313  ctx->total[0] += len;
314  if (ctx->total[0] < len)
315    ++ctx->total[1];
316
317  /* Process all bytes in the buffer with 64 bytes in each round of
318     the loop.  */
319  while (words < endp)
320    {
321      md5_uint32 *cwp = correct_words;
322      md5_uint32 A_save = A;
323      md5_uint32 B_save = B;
324      md5_uint32 C_save = C;
325      md5_uint32 D_save = D;
326
327      /* First round: using the given function, the context and a constant
328	 the next context is computed.  Because the algorithms processing
329	 unit is a 32-bit word and it is determined to work on words in
330	 little endian byte order we perhaps have to change the byte order
331	 before the computation.  To reduce the work for the next steps
332	 we store the swapped words in the array CORRECT_WORDS.  */
333
334#define OP(a, b, c, d, s, T)						\
335      do								\
336        {								\
337	  a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T;		\
338	  ++words;							\
339	  CYCLIC (a, s);						\
340	  a += b;							\
341        }								\
342      while (0)
343
344      /* It is unfortunate that C does not provide an operator for
345	 cyclic rotation.  Hope the C compiler is smart enough.  */
346#define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s)))
347
348      /* Before we start, one word to the strange constants.
349	 They are defined in RFC 1321 as
350
351	 T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64
352       */
353
354      /* Round 1.  */
355      OP (A, B, C, D,  7, 0xd76aa478);
356      OP (D, A, B, C, 12, 0xe8c7b756);
357      OP (C, D, A, B, 17, 0x242070db);
358      OP (B, C, D, A, 22, 0xc1bdceee);
359      OP (A, B, C, D,  7, 0xf57c0faf);
360      OP (D, A, B, C, 12, 0x4787c62a);
361      OP (C, D, A, B, 17, 0xa8304613);
362      OP (B, C, D, A, 22, 0xfd469501);
363      OP (A, B, C, D,  7, 0x698098d8);
364      OP (D, A, B, C, 12, 0x8b44f7af);
365      OP (C, D, A, B, 17, 0xffff5bb1);
366      OP (B, C, D, A, 22, 0x895cd7be);
367      OP (A, B, C, D,  7, 0x6b901122);
368      OP (D, A, B, C, 12, 0xfd987193);
369      OP (C, D, A, B, 17, 0xa679438e);
370      OP (B, C, D, A, 22, 0x49b40821);
371
372      /* For the second to fourth round we have the possibly swapped words
373	 in CORRECT_WORDS.  Redefine the macro to take an additional first
374	 argument specifying the function to use.  */
375#undef OP
376#define OP(f, a, b, c, d, k, s, T)					\
377      do 								\
378	{								\
379	  a += f (b, c, d) + correct_words[k] + T;			\
380	  CYCLIC (a, s);						\
381	  a += b;							\
382	}								\
383      while (0)
384
385      /* Round 2.  */
386      OP (FG, A, B, C, D,  1,  5, 0xf61e2562);
387      OP (FG, D, A, B, C,  6,  9, 0xc040b340);
388      OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
389      OP (FG, B, C, D, A,  0, 20, 0xe9b6c7aa);
390      OP (FG, A, B, C, D,  5,  5, 0xd62f105d);
391      OP (FG, D, A, B, C, 10,  9, 0x02441453);
392      OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
393      OP (FG, B, C, D, A,  4, 20, 0xe7d3fbc8);
394      OP (FG, A, B, C, D,  9,  5, 0x21e1cde6);
395      OP (FG, D, A, B, C, 14,  9, 0xc33707d6);
396      OP (FG, C, D, A, B,  3, 14, 0xf4d50d87);
397      OP (FG, B, C, D, A,  8, 20, 0x455a14ed);
398      OP (FG, A, B, C, D, 13,  5, 0xa9e3e905);
399      OP (FG, D, A, B, C,  2,  9, 0xfcefa3f8);
400      OP (FG, C, D, A, B,  7, 14, 0x676f02d9);
401      OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);
402
403      /* Round 3.  */
404      OP (FH, A, B, C, D,  5,  4, 0xfffa3942);
405      OP (FH, D, A, B, C,  8, 11, 0x8771f681);
406      OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
407      OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
408      OP (FH, A, B, C, D,  1,  4, 0xa4beea44);
409      OP (FH, D, A, B, C,  4, 11, 0x4bdecfa9);
410      OP (FH, C, D, A, B,  7, 16, 0xf6bb4b60);
411      OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
412      OP (FH, A, B, C, D, 13,  4, 0x289b7ec6);
413      OP (FH, D, A, B, C,  0, 11, 0xeaa127fa);
414      OP (FH, C, D, A, B,  3, 16, 0xd4ef3085);
415      OP (FH, B, C, D, A,  6, 23, 0x04881d05);
416      OP (FH, A, B, C, D,  9,  4, 0xd9d4d039);
417      OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
418      OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
419      OP (FH, B, C, D, A,  2, 23, 0xc4ac5665);
420
421      /* Round 4.  */
422      OP (FI, A, B, C, D,  0,  6, 0xf4292244);
423      OP (FI, D, A, B, C,  7, 10, 0x432aff97);
424      OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
425      OP (FI, B, C, D, A,  5, 21, 0xfc93a039);
426      OP (FI, A, B, C, D, 12,  6, 0x655b59c3);
427      OP (FI, D, A, B, C,  3, 10, 0x8f0ccc92);
428      OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
429      OP (FI, B, C, D, A,  1, 21, 0x85845dd1);
430      OP (FI, A, B, C, D,  8,  6, 0x6fa87e4f);
431      OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
432      OP (FI, C, D, A, B,  6, 15, 0xa3014314);
433      OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
434      OP (FI, A, B, C, D,  4,  6, 0xf7537e82);
435      OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
436      OP (FI, C, D, A, B,  2, 15, 0x2ad7d2bb);
437      OP (FI, B, C, D, A,  9, 21, 0xeb86d391);
438
439      /* Add the starting values of the context.  */
440      A += A_save;
441      B += B_save;
442      C += C_save;
443      D += D_save;
444    }
445
446  /* Put checksum in context given as argument.  */
447  ctx->A = A;
448  ctx->B = B;
449  ctx->C = C;
450  ctx->D = D;
451}
452