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, 2011 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: RESBUF may not be aligned as strongly as MD5_UNIT32 so we
80   put things in a local (aligned) buffer first, then memcpy into RESBUF.  */
81void *
82md5_read_ctx (const struct md5_ctx *ctx, void *resbuf)
83{
84  md5_uint32 buffer[4];
85
86  buffer[0] = SWAP (ctx->A);
87  buffer[1] = SWAP (ctx->B);
88  buffer[2] = SWAP (ctx->C);
89  buffer[3] = SWAP (ctx->D);
90
91  memcpy (resbuf, buffer, 16);
92
93  return resbuf;
94}
95
96/* Process the remaining bytes in the internal buffer and the usual
97   prolog according to the standard and write the result to RESBUF.
98
99   IMPORTANT: On some systems it is required that RESBUF is correctly
100   aligned for a 32 bits value.  */
101void *
102md5_finish_ctx (struct md5_ctx *ctx, void *resbuf)
103{
104  /* Take yet unprocessed bytes into account.  */
105  md5_uint32 bytes = ctx->buflen;
106  md5_uint32 swap_bytes;
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     Use memcpy to avoid aliasing problems.  On most systems, this
119     will be optimized away to the same code.  */
120  swap_bytes = SWAP (ctx->total[0] << 3);
121  memcpy (&ctx->buffer[bytes + pad], &swap_bytes, sizeof (swap_bytes));
122  swap_bytes = SWAP ((ctx->total[1] << 3) | (ctx->total[0] >> 29));
123  memcpy (&ctx->buffer[bytes + pad + 4], &swap_bytes, sizeof (swap_bytes));
124
125  /* Process last bytes.  */
126  md5_process_block (ctx->buffer, bytes + pad + 8, ctx);
127
128  return md5_read_ctx (ctx, resbuf);
129}
130
131/* Compute MD5 message digest for bytes read from STREAM.  The
132   resulting message digest number will be written into the 16 bytes
133   beginning at RESBLOCK.  */
134int
135md5_stream (FILE *stream, void *resblock)
136{
137  /* Important: BLOCKSIZE must be a multiple of 64.  */
138#define BLOCKSIZE 4096
139  struct md5_ctx ctx;
140  char buffer[BLOCKSIZE + 72];
141  size_t sum;
142
143  /* Initialize the computation context.  */
144  md5_init_ctx (&ctx);
145
146  /* Iterate over full file contents.  */
147  while (1)
148    {
149      /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
150	 computation function processes the whole buffer so that with the
151	 next round of the loop another block can be read.  */
152      size_t n;
153      sum = 0;
154
155      /* Read block.  Take care for partial reads.  */
156      do
157	{
158	  n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
159
160	  sum += n;
161	}
162      while (sum < BLOCKSIZE && n != 0);
163      if (n == 0 && ferror (stream))
164        return 1;
165
166      /* If end of file is reached, end the loop.  */
167      if (n == 0)
168	break;
169
170      /* Process buffer with BLOCKSIZE bytes.  Note that
171			BLOCKSIZE % 64 == 0
172       */
173      md5_process_block (buffer, BLOCKSIZE, &ctx);
174    }
175
176  /* Add the last bytes if necessary.  */
177  if (sum > 0)
178    md5_process_bytes (buffer, sum, &ctx);
179
180  /* Construct result in desired memory.  */
181  md5_finish_ctx (&ctx, resblock);
182  return 0;
183}
184
185/* Compute MD5 message digest for LEN bytes beginning at BUFFER.  The
186   result is always in little endian byte order, so that a byte-wise
187   output yields to the wanted ASCII representation of the message
188   digest.  */
189void *
190md5_buffer (const char *buffer, size_t len, void *resblock)
191{
192  struct md5_ctx ctx;
193
194  /* Initialize the computation context.  */
195  md5_init_ctx (&ctx);
196
197  /* Process whole buffer but last len % 64 bytes.  */
198  md5_process_bytes (buffer, len, &ctx);
199
200  /* Put result in desired memory area.  */
201  return md5_finish_ctx (&ctx, resblock);
202}
203
204
205void
206md5_process_bytes (const void *buffer, size_t len, struct md5_ctx *ctx)
207{
208  /* When we already have some bits in our internal buffer concatenate
209     both inputs first.  */
210  if (ctx->buflen != 0)
211    {
212      size_t left_over = ctx->buflen;
213      size_t add = 128 - left_over > len ? len : 128 - left_over;
214
215      memcpy (&ctx->buffer[left_over], buffer, add);
216      ctx->buflen += add;
217
218      if (left_over + add > 64)
219	{
220	  md5_process_block (ctx->buffer, (left_over + add) & ~63, ctx);
221	  /* The regions in the following copy operation cannot overlap.  */
222	  memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
223		  (left_over + add) & 63);
224	  ctx->buflen = (left_over + add) & 63;
225	}
226
227      buffer = (const void *) ((const char *) buffer + add);
228      len -= add;
229    }
230
231  /* Process available complete blocks.  */
232  if (len > 64)
233    {
234#if !_STRING_ARCH_unaligned
235/* To check alignment gcc has an appropriate operator.  Other
236   compilers don't.  */
237# if __GNUC__ >= 2
238#  define UNALIGNED_P(p) (((md5_uintptr) p) % __alignof__ (md5_uint32) != 0)
239# else
240#  define UNALIGNED_P(p) (((md5_uintptr) p) % sizeof (md5_uint32) != 0)
241# endif
242      if (UNALIGNED_P (buffer))
243        while (len > 64)
244          {
245	    memcpy (ctx->buffer, buffer, 64);
246            md5_process_block (ctx->buffer, 64, ctx);
247            buffer = (const char *) buffer + 64;
248            len -= 64;
249          }
250      else
251#endif
252	{
253	  md5_process_block (buffer, len & ~63, ctx);
254	  buffer = (const void *) ((const char *) buffer + (len & ~63));
255	  len &= 63;
256	}
257    }
258
259  /* Move remaining bytes in internal buffer.  */
260  if (len > 0)
261    {
262      memcpy (ctx->buffer, buffer, len);
263      ctx->buflen = len;
264    }
265}
266
267
268/* These are the four functions used in the four steps of the MD5 algorithm
269   and defined in the RFC 1321.  The first function is a little bit optimized
270   (as found in Colin Plumbs public domain implementation).  */
271/* #define FF(b, c, d) ((b & c) | (~b & d)) */
272#define FF(b, c, d) (d ^ (b & (c ^ d)))
273#define FG(b, c, d) FF (d, b, c)
274#define FH(b, c, d) (b ^ c ^ d)
275#define FI(b, c, d) (c ^ (b | ~d))
276
277/* Process LEN bytes of BUFFER, accumulating context into CTX.
278   It is assumed that LEN % 64 == 0.  */
279
280void
281md5_process_block (const void *buffer, size_t len, struct md5_ctx *ctx)
282{
283  md5_uint32 correct_words[16];
284  const md5_uint32 *words = (const md5_uint32 *) buffer;
285  size_t nwords = len / sizeof (md5_uint32);
286  const md5_uint32 *endp = words + nwords;
287  md5_uint32 A = ctx->A;
288  md5_uint32 B = ctx->B;
289  md5_uint32 C = ctx->C;
290  md5_uint32 D = ctx->D;
291
292  /* First increment the byte count.  RFC 1321 specifies the possible
293     length of the file up to 2^64 bits.  Here we only compute the
294     number of bytes.  Do a double word increment.  */
295  ctx->total[0] += len;
296  ctx->total[1] += ((len >> 31) >> 1) + (ctx->total[0] < len);
297
298  /* Process all bytes in the buffer with 64 bytes in each round of
299     the loop.  */
300  while (words < endp)
301    {
302      md5_uint32 *cwp = correct_words;
303      md5_uint32 A_save = A;
304      md5_uint32 B_save = B;
305      md5_uint32 C_save = C;
306      md5_uint32 D_save = D;
307
308      /* First round: using the given function, the context and a constant
309	 the next context is computed.  Because the algorithms processing
310	 unit is a 32-bit word and it is determined to work on words in
311	 little endian byte order we perhaps have to change the byte order
312	 before the computation.  To reduce the work for the next steps
313	 we store the swapped words in the array CORRECT_WORDS.  */
314
315#define OP(a, b, c, d, s, T)						\
316      do								\
317        {								\
318	  a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T;		\
319	  ++words;							\
320	  CYCLIC (a, s);						\
321	  a += b;							\
322        }								\
323      while (0)
324
325      /* It is unfortunate that C does not provide an operator for
326	 cyclic rotation.  Hope the C compiler is smart enough.  */
327#define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s)))
328
329      /* Before we start, one word to the strange constants.
330	 They are defined in RFC 1321 as
331
332	 T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64
333       */
334
335      /* Round 1.  */
336      OP (A, B, C, D,  7, (md5_uint32) 0xd76aa478);
337      OP (D, A, B, C, 12, (md5_uint32) 0xe8c7b756);
338      OP (C, D, A, B, 17, (md5_uint32) 0x242070db);
339      OP (B, C, D, A, 22, (md5_uint32) 0xc1bdceee);
340      OP (A, B, C, D,  7, (md5_uint32) 0xf57c0faf);
341      OP (D, A, B, C, 12, (md5_uint32) 0x4787c62a);
342      OP (C, D, A, B, 17, (md5_uint32) 0xa8304613);
343      OP (B, C, D, A, 22, (md5_uint32) 0xfd469501);
344      OP (A, B, C, D,  7, (md5_uint32) 0x698098d8);
345      OP (D, A, B, C, 12, (md5_uint32) 0x8b44f7af);
346      OP (C, D, A, B, 17, (md5_uint32) 0xffff5bb1);
347      OP (B, C, D, A, 22, (md5_uint32) 0x895cd7be);
348      OP (A, B, C, D,  7, (md5_uint32) 0x6b901122);
349      OP (D, A, B, C, 12, (md5_uint32) 0xfd987193);
350      OP (C, D, A, B, 17, (md5_uint32) 0xa679438e);
351      OP (B, C, D, A, 22, (md5_uint32) 0x49b40821);
352
353      /* For the second to fourth round we have the possibly swapped words
354	 in CORRECT_WORDS.  Redefine the macro to take an additional first
355	 argument specifying the function to use.  */
356#undef OP
357#define OP(a, b, c, d, k, s, T)						\
358      do 								\
359	{								\
360	  a += FX (b, c, d) + correct_words[k] + T;			\
361	  CYCLIC (a, s);						\
362	  a += b;							\
363	}								\
364      while (0)
365
366#define FX(b, c, d) FG (b, c, d)
367
368      /* Round 2.  */
369      OP (A, B, C, D,  1,  5, (md5_uint32) 0xf61e2562);
370      OP (D, A, B, C,  6,  9, (md5_uint32) 0xc040b340);
371      OP (C, D, A, B, 11, 14, (md5_uint32) 0x265e5a51);
372      OP (B, C, D, A,  0, 20, (md5_uint32) 0xe9b6c7aa);
373      OP (A, B, C, D,  5,  5, (md5_uint32) 0xd62f105d);
374      OP (D, A, B, C, 10,  9, (md5_uint32) 0x02441453);
375      OP (C, D, A, B, 15, 14, (md5_uint32) 0xd8a1e681);
376      OP (B, C, D, A,  4, 20, (md5_uint32) 0xe7d3fbc8);
377      OP (A, B, C, D,  9,  5, (md5_uint32) 0x21e1cde6);
378      OP (D, A, B, C, 14,  9, (md5_uint32) 0xc33707d6);
379      OP (C, D, A, B,  3, 14, (md5_uint32) 0xf4d50d87);
380      OP (B, C, D, A,  8, 20, (md5_uint32) 0x455a14ed);
381      OP (A, B, C, D, 13,  5, (md5_uint32) 0xa9e3e905);
382      OP (D, A, B, C,  2,  9, (md5_uint32) 0xfcefa3f8);
383      OP (C, D, A, B,  7, 14, (md5_uint32) 0x676f02d9);
384      OP (B, C, D, A, 12, 20, (md5_uint32) 0x8d2a4c8a);
385
386#undef FX
387#define FX(b, c, d) FH (b, c, d)
388
389      /* Round 3.  */
390      OP (A, B, C, D,  5,  4, (md5_uint32) 0xfffa3942);
391      OP (D, A, B, C,  8, 11, (md5_uint32) 0x8771f681);
392      OP (C, D, A, B, 11, 16, (md5_uint32) 0x6d9d6122);
393      OP (B, C, D, A, 14, 23, (md5_uint32) 0xfde5380c);
394      OP (A, B, C, D,  1,  4, (md5_uint32) 0xa4beea44);
395      OP (D, A, B, C,  4, 11, (md5_uint32) 0x4bdecfa9);
396      OP (C, D, A, B,  7, 16, (md5_uint32) 0xf6bb4b60);
397      OP (B, C, D, A, 10, 23, (md5_uint32) 0xbebfbc70);
398      OP (A, B, C, D, 13,  4, (md5_uint32) 0x289b7ec6);
399      OP (D, A, B, C,  0, 11, (md5_uint32) 0xeaa127fa);
400      OP (C, D, A, B,  3, 16, (md5_uint32) 0xd4ef3085);
401      OP (B, C, D, A,  6, 23, (md5_uint32) 0x04881d05);
402      OP (A, B, C, D,  9,  4, (md5_uint32) 0xd9d4d039);
403      OP (D, A, B, C, 12, 11, (md5_uint32) 0xe6db99e5);
404      OP (C, D, A, B, 15, 16, (md5_uint32) 0x1fa27cf8);
405      OP (B, C, D, A,  2, 23, (md5_uint32) 0xc4ac5665);
406
407#undef FX
408#define FX(b, c, d) FI (b, c, d)
409
410      /* Round 4.  */
411      OP (A, B, C, D,  0,  6, (md5_uint32) 0xf4292244);
412      OP (D, A, B, C,  7, 10, (md5_uint32) 0x432aff97);
413      OP (C, D, A, B, 14, 15, (md5_uint32) 0xab9423a7);
414      OP (B, C, D, A,  5, 21, (md5_uint32) 0xfc93a039);
415      OP (A, B, C, D, 12,  6, (md5_uint32) 0x655b59c3);
416      OP (D, A, B, C,  3, 10, (md5_uint32) 0x8f0ccc92);
417      OP (C, D, A, B, 10, 15, (md5_uint32) 0xffeff47d);
418      OP (B, C, D, A,  1, 21, (md5_uint32) 0x85845dd1);
419      OP (A, B, C, D,  8,  6, (md5_uint32) 0x6fa87e4f);
420      OP (D, A, B, C, 15, 10, (md5_uint32) 0xfe2ce6e0);
421      OP (C, D, A, B,  6, 15, (md5_uint32) 0xa3014314);
422      OP (B, C, D, A, 13, 21, (md5_uint32) 0x4e0811a1);
423      OP (A, B, C, D,  4,  6, (md5_uint32) 0xf7537e82);
424      OP (D, A, B, C, 11, 10, (md5_uint32) 0xbd3af235);
425      OP (C, D, A, B,  2, 15, (md5_uint32) 0x2ad7d2bb);
426      OP (B, C, D, A,  9, 21, (md5_uint32) 0xeb86d391);
427
428      /* Add the starting values of the context.  */
429      A += A_save;
430      B += B_save;
431      C += C_save;
432      D += D_save;
433    }
434
435  /* Put checksum in context given as argument.  */
436  ctx->A = A;
437  ctx->B = B;
438  ctx->C = C;
439  ctx->D = D;
440}
441