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., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, 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 (struct md5_ctx *ctx)
66{
67  ctx->A = (md5_uint32) 0x67452301;
68  ctx->B = (md5_uint32) 0xefcdab89;
69  ctx->C = (md5_uint32) 0x98badcfe;
70  ctx->D = (md5_uint32) 0x10325476;
71
72  ctx->total[0] = ctx->total[1] = 0;
73  ctx->buflen = 0;
74}
75
76/* Put result from CTX in first 16 bytes following RESBUF.  The result
77   must be in little endian byte order.
78
79   IMPORTANT: On some systems it is required that RESBUF is correctly
80   aligned for a 32 bits value.  */
81void *
82md5_read_ctx (const struct md5_ctx *ctx, void *resbuf)
83{
84  ((md5_uint32 *) resbuf)[0] = SWAP (ctx->A);
85  ((md5_uint32 *) resbuf)[1] = SWAP (ctx->B);
86  ((md5_uint32 *) resbuf)[2] = SWAP (ctx->C);
87  ((md5_uint32 *) resbuf)[3] = SWAP (ctx->D);
88
89  return resbuf;
90}
91
92/* Process the remaining bytes in the internal buffer and the usual
93   prolog according to the standard and write the result to RESBUF.
94
95   IMPORTANT: On some systems it is required that RESBUF is correctly
96   aligned for a 32 bits value.  */
97void *
98md5_finish_ctx (struct md5_ctx *ctx, void *resbuf)
99{
100  /* Take yet unprocessed bytes into account.  */
101  md5_uint32 bytes = ctx->buflen;
102  size_t pad;
103
104  /* Now count remaining bytes.  */
105  ctx->total[0] += bytes;
106  if (ctx->total[0] < bytes)
107    ++ctx->total[1];
108
109  pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
110  memcpy (&ctx->buffer[bytes], fillbuf, pad);
111
112  /* Put the 64-bit file length in *bits* at the end of the buffer.  */
113  *(md5_uint32 *) &ctx->buffer[bytes + pad] = SWAP (ctx->total[0] << 3);
114  *(md5_uint32 *) &ctx->buffer[bytes + pad + 4] = SWAP ((ctx->total[1] << 3) |
115							(ctx->total[0] >> 29));
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/* Compute MD5 message digest for bytes read from STREAM.  The
124   resulting message digest number will be written into the 16 bytes
125   beginning at RESBLOCK.  */
126int
127md5_stream (FILE *stream, void *resblock)
128{
129  /* Important: BLOCKSIZE must be a multiple of 64.  */
130#define BLOCKSIZE 4096
131  struct md5_ctx ctx;
132  char buffer[BLOCKSIZE + 72];
133  size_t sum;
134
135  /* Initialize the computation context.  */
136  md5_init_ctx (&ctx);
137
138  /* Iterate over full file contents.  */
139  while (1)
140    {
141      /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
142	 computation function processes the whole buffer so that with the
143	 next round of the loop another block can be read.  */
144      size_t n;
145      sum = 0;
146
147      /* Read block.  Take care for partial reads.  */
148      do
149	{
150	  n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
151
152	  sum += n;
153	}
154      while (sum < BLOCKSIZE && n != 0);
155      if (n == 0 && ferror (stream))
156        return 1;
157
158      /* If end of file is reached, end the loop.  */
159      if (n == 0)
160	break;
161
162      /* Process buffer with BLOCKSIZE bytes.  Note that
163			BLOCKSIZE % 64 == 0
164       */
165      md5_process_block (buffer, BLOCKSIZE, &ctx);
166    }
167
168  /* Add the last bytes if necessary.  */
169  if (sum > 0)
170    md5_process_bytes (buffer, sum, &ctx);
171
172  /* Construct result in desired memory.  */
173  md5_finish_ctx (&ctx, resblock);
174  return 0;
175}
176
177/* Compute MD5 message digest for LEN bytes beginning at BUFFER.  The
178   result is always in little endian byte order, so that a byte-wise
179   output yields to the wanted ASCII representation of the message
180   digest.  */
181void *
182md5_buffer (const char *buffer, size_t len, void *resblock)
183{
184  struct md5_ctx ctx;
185
186  /* Initialize the computation context.  */
187  md5_init_ctx (&ctx);
188
189  /* Process whole buffer but last len % 64 bytes.  */
190  md5_process_bytes (buffer, len, &ctx);
191
192  /* Put result in desired memory area.  */
193  return md5_finish_ctx (&ctx, resblock);
194}
195
196
197void
198md5_process_bytes (const void *buffer, size_t len, struct md5_ctx *ctx)
199{
200  /* When we already have some bits in our internal buffer concatenate
201     both inputs first.  */
202  if (ctx->buflen != 0)
203    {
204      size_t left_over = ctx->buflen;
205      size_t add = 128 - left_over > len ? len : 128 - left_over;
206
207      memcpy (&ctx->buffer[left_over], buffer, add);
208      ctx->buflen += add;
209
210      if (left_over + add > 64)
211	{
212	  md5_process_block (ctx->buffer, (left_over + add) & ~63, ctx);
213	  /* The regions in the following copy operation cannot overlap.  */
214	  memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
215		  (left_over + add) & 63);
216	  ctx->buflen = (left_over + add) & 63;
217	}
218
219      buffer = (const void *) ((const char *) buffer + add);
220      len -= add;
221    }
222
223  /* Process available complete blocks.  */
224  if (len > 64)
225    {
226#if !_STRING_ARCH_unaligned
227/* To check alignment gcc has an appropriate operator.  Other
228   compilers don't.  */
229# if __GNUC__ >= 2
230#  define UNALIGNED_P(p) (((md5_uintptr) p) % __alignof__ (md5_uint32) != 0)
231# else
232#  define UNALIGNED_P(p) (((md5_uintptr) p) % sizeof (md5_uint32) != 0)
233# endif
234      if (UNALIGNED_P (buffer))
235        while (len > 64)
236          {
237            md5_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
238            buffer = (const char *) buffer + 64;
239            len -= 64;
240          }
241      else
242#endif
243      md5_process_block (buffer, len & ~63, ctx);
244      buffer = (const void *) ((const char *) buffer + (len & ~63));
245      len &= 63;
246    }
247
248  /* Move remaining bytes in internal buffer.  */
249  if (len > 0)
250    {
251      memcpy (ctx->buffer, buffer, len);
252      ctx->buflen = len;
253    }
254}
255
256
257/* These are the four functions used in the four steps of the MD5 algorithm
258   and defined in the RFC 1321.  The first function is a little bit optimized
259   (as found in Colin Plumbs public domain implementation).  */
260/* #define FF(b, c, d) ((b & c) | (~b & d)) */
261#define FF(b, c, d) (d ^ (b & (c ^ d)))
262#define FG(b, c, d) FF (d, b, c)
263#define FH(b, c, d) (b ^ c ^ d)
264#define FI(b, c, d) (c ^ (b | ~d))
265
266/* Process LEN bytes of BUFFER, accumulating context into CTX.
267   It is assumed that LEN % 64 == 0.  */
268
269void
270md5_process_block (const void *buffer, size_t len, struct md5_ctx *ctx)
271{
272  md5_uint32 correct_words[16];
273  const md5_uint32 *words = (const md5_uint32 *) buffer;
274  size_t nwords = len / sizeof (md5_uint32);
275  const md5_uint32 *endp = words + nwords;
276  md5_uint32 A = ctx->A;
277  md5_uint32 B = ctx->B;
278  md5_uint32 C = ctx->C;
279  md5_uint32 D = ctx->D;
280
281  /* First increment the byte count.  RFC 1321 specifies the possible
282     length of the file up to 2^64 bits.  Here we only compute the
283     number of bytes.  Do a double word increment.  */
284  ctx->total[0] += len;
285  if (ctx->total[0] < len)
286    ++ctx->total[1];
287
288  /* Process all bytes in the buffer with 64 bytes in each round of
289     the loop.  */
290  while (words < endp)
291    {
292      md5_uint32 *cwp = correct_words;
293      md5_uint32 A_save = A;
294      md5_uint32 B_save = B;
295      md5_uint32 C_save = C;
296      md5_uint32 D_save = D;
297
298      /* First round: using the given function, the context and a constant
299	 the next context is computed.  Because the algorithms processing
300	 unit is a 32-bit word and it is determined to work on words in
301	 little endian byte order we perhaps have to change the byte order
302	 before the computation.  To reduce the work for the next steps
303	 we store the swapped words in the array CORRECT_WORDS.  */
304
305#define OP(a, b, c, d, s, T)						\
306      do								\
307        {								\
308	  a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T;		\
309	  ++words;							\
310	  CYCLIC (a, s);						\
311	  a += b;							\
312        }								\
313      while (0)
314
315      /* It is unfortunate that C does not provide an operator for
316	 cyclic rotation.  Hope the C compiler is smart enough.  */
317#define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s)))
318
319      /* Before we start, one word to the strange constants.
320	 They are defined in RFC 1321 as
321
322	 T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64
323       */
324
325      /* Round 1.  */
326      OP (A, B, C, D,  7, (md5_uint32) 0xd76aa478);
327      OP (D, A, B, C, 12, (md5_uint32) 0xe8c7b756);
328      OP (C, D, A, B, 17, (md5_uint32) 0x242070db);
329      OP (B, C, D, A, 22, (md5_uint32) 0xc1bdceee);
330      OP (A, B, C, D,  7, (md5_uint32) 0xf57c0faf);
331      OP (D, A, B, C, 12, (md5_uint32) 0x4787c62a);
332      OP (C, D, A, B, 17, (md5_uint32) 0xa8304613);
333      OP (B, C, D, A, 22, (md5_uint32) 0xfd469501);
334      OP (A, B, C, D,  7, (md5_uint32) 0x698098d8);
335      OP (D, A, B, C, 12, (md5_uint32) 0x8b44f7af);
336      OP (C, D, A, B, 17, (md5_uint32) 0xffff5bb1);
337      OP (B, C, D, A, 22, (md5_uint32) 0x895cd7be);
338      OP (A, B, C, D,  7, (md5_uint32) 0x6b901122);
339      OP (D, A, B, C, 12, (md5_uint32) 0xfd987193);
340      OP (C, D, A, B, 17, (md5_uint32) 0xa679438e);
341      OP (B, C, D, A, 22, (md5_uint32) 0x49b40821);
342
343      /* For the second to fourth round we have the possibly swapped words
344	 in CORRECT_WORDS.  Redefine the macro to take an additional first
345	 argument specifying the function to use.  */
346#undef OP
347#define OP(a, b, c, d, k, s, T)						\
348      do 								\
349	{								\
350	  a += FX (b, c, d) + correct_words[k] + T;			\
351	  CYCLIC (a, s);						\
352	  a += b;							\
353	}								\
354      while (0)
355
356#define FX(b, c, d) FG (b, c, d)
357
358      /* Round 2.  */
359      OP (A, B, C, D,  1,  5, (md5_uint32) 0xf61e2562);
360      OP (D, A, B, C,  6,  9, (md5_uint32) 0xc040b340);
361      OP (C, D, A, B, 11, 14, (md5_uint32) 0x265e5a51);
362      OP (B, C, D, A,  0, 20, (md5_uint32) 0xe9b6c7aa);
363      OP (A, B, C, D,  5,  5, (md5_uint32) 0xd62f105d);
364      OP (D, A, B, C, 10,  9, (md5_uint32) 0x02441453);
365      OP (C, D, A, B, 15, 14, (md5_uint32) 0xd8a1e681);
366      OP (B, C, D, A,  4, 20, (md5_uint32) 0xe7d3fbc8);
367      OP (A, B, C, D,  9,  5, (md5_uint32) 0x21e1cde6);
368      OP (D, A, B, C, 14,  9, (md5_uint32) 0xc33707d6);
369      OP (C, D, A, B,  3, 14, (md5_uint32) 0xf4d50d87);
370      OP (B, C, D, A,  8, 20, (md5_uint32) 0x455a14ed);
371      OP (A, B, C, D, 13,  5, (md5_uint32) 0xa9e3e905);
372      OP (D, A, B, C,  2,  9, (md5_uint32) 0xfcefa3f8);
373      OP (C, D, A, B,  7, 14, (md5_uint32) 0x676f02d9);
374      OP (B, C, D, A, 12, 20, (md5_uint32) 0x8d2a4c8a);
375
376#undef FX
377#define FX(b, c, d) FH (b, c, d)
378
379      /* Round 3.  */
380      OP (A, B, C, D,  5,  4, (md5_uint32) 0xfffa3942);
381      OP (D, A, B, C,  8, 11, (md5_uint32) 0x8771f681);
382      OP (C, D, A, B, 11, 16, (md5_uint32) 0x6d9d6122);
383      OP (B, C, D, A, 14, 23, (md5_uint32) 0xfde5380c);
384      OP (A, B, C, D,  1,  4, (md5_uint32) 0xa4beea44);
385      OP (D, A, B, C,  4, 11, (md5_uint32) 0x4bdecfa9);
386      OP (C, D, A, B,  7, 16, (md5_uint32) 0xf6bb4b60);
387      OP (B, C, D, A, 10, 23, (md5_uint32) 0xbebfbc70);
388      OP (A, B, C, D, 13,  4, (md5_uint32) 0x289b7ec6);
389      OP (D, A, B, C,  0, 11, (md5_uint32) 0xeaa127fa);
390      OP (C, D, A, B,  3, 16, (md5_uint32) 0xd4ef3085);
391      OP (B, C, D, A,  6, 23, (md5_uint32) 0x04881d05);
392      OP (A, B, C, D,  9,  4, (md5_uint32) 0xd9d4d039);
393      OP (D, A, B, C, 12, 11, (md5_uint32) 0xe6db99e5);
394      OP (C, D, A, B, 15, 16, (md5_uint32) 0x1fa27cf8);
395      OP (B, C, D, A,  2, 23, (md5_uint32) 0xc4ac5665);
396
397#undef FX
398#define FX(b, c, d) FI (b, c, d)
399
400      /* Round 4.  */
401      OP (A, B, C, D,  0,  6, (md5_uint32) 0xf4292244);
402      OP (D, A, B, C,  7, 10, (md5_uint32) 0x432aff97);
403      OP (C, D, A, B, 14, 15, (md5_uint32) 0xab9423a7);
404      OP (B, C, D, A,  5, 21, (md5_uint32) 0xfc93a039);
405      OP (A, B, C, D, 12,  6, (md5_uint32) 0x655b59c3);
406      OP (D, A, B, C,  3, 10, (md5_uint32) 0x8f0ccc92);
407      OP (C, D, A, B, 10, 15, (md5_uint32) 0xffeff47d);
408      OP (B, C, D, A,  1, 21, (md5_uint32) 0x85845dd1);
409      OP (A, B, C, D,  8,  6, (md5_uint32) 0x6fa87e4f);
410      OP (D, A, B, C, 15, 10, (md5_uint32) 0xfe2ce6e0);
411      OP (C, D, A, B,  6, 15, (md5_uint32) 0xa3014314);
412      OP (B, C, D, A, 13, 21, (md5_uint32) 0x4e0811a1);
413      OP (A, B, C, D,  4,  6, (md5_uint32) 0xf7537e82);
414      OP (D, A, B, C, 11, 10, (md5_uint32) 0xbd3af235);
415      OP (C, D, A, B,  2, 15, (md5_uint32) 0x2ad7d2bb);
416      OP (B, C, D, A,  9, 21, (md5_uint32) 0xeb86d391);
417
418      /* Add the starting values of the context.  */
419      A += A_save;
420      B += B_save;
421      C += C_save;
422      D += D_save;
423    }
424
425  /* Put checksum in context given as argument.  */
426  ctx->A = A;
427  ctx->B = B;
428  ctx->C = C;
429  ctx->D = D;
430}
431