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) 1995,1996,1997,1999,2000,2001,2005
4    Free Software Foundation, Inc.
5   This file is part of the GNU C Library.
6
7   The GNU C Library is free software; you can redistribute it and/or
8   modify it under the terms of the GNU Lesser General Public
9   License as published by the Free Software Foundation; either
10   version 2.1 of the License, or (at your option) any later version.
11
12   The GNU C Library is distributed in the hope that it will be useful,
13   but WITHOUT ANY WARRANTY; without even the implied warranty of
14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15   Lesser General Public License for more details.
16
17   You should have received a copy of the GNU Lesser General Public
18   License along with the GNU C Library; if not, write to the Free
19   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
20   02111-1307 USA.  */
21
22/* Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.  */
23
24#include <sys/types.h>
25
26# include <stdlib.h>
27# include <string.h>
28
29#include "md5.h"
30
31/* #ifdef _LIBC */
32# include <endian.h>
33# if __BYTE_ORDER == __BIG_ENDIAN
34#  define WORDS_BIGENDIAN 1
35# endif
36/* We need to keep the namespace clean so define the MD5 function
37   protected using leading __ .  */
38# define md5_init_ctx __md5_init_ctx
39# define md5_process_block __md5_process_block
40# define md5_process_bytes __md5_process_bytes
41# define md5_finish_ctx __md5_finish_ctx
42# define md5_read_ctx __md5_read_ctx
43# define md5_stream __md5_stream
44# define md5_buffer __md5_buffer
45/* #endif */
46
47#ifdef WORDS_BIGENDIAN
48# define SWAP(n)                                                        \
49    (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
50#else
51# define SWAP(n) (n)
52#endif
53
54void
55md5_process_bytes (const void *buffer, size_t len, struct md5_ctx *ctx);
56void
57md5_process_block (const void *buffer, size_t len, struct md5_ctx *ctx);
58
59/* This array contains the bytes used to pad the buffer to the next
60   64-byte boundary.  (RFC 1321, 3.1: Step 1)  */
61static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */ };
62
63
64/* Initialize structure containing state of computation.
65   (RFC 1321, 3.3: Step 3)  */
66void
67md5_init_ctx (ctx)
68     struct md5_ctx *ctx;
69{
70  ctx->A = 0x67452301;
71  ctx->B = 0xefcdab89;
72  ctx->C = 0x98badcfe;
73  ctx->D = 0x10325476;
74
75  ctx->total[0] = ctx->total[1] = 0;
76  ctx->buflen = 0;
77}
78
79/* Put result from CTX in first 16 bytes following RESBUF.  The result
80   must be in little endian byte order.
81
82   IMPORTANT: On some systems it is required that RESBUF is correctly
83   aligned for a 32 bits value.  */
84void *
85md5_read_ctx (ctx, resbuf)
86     const struct md5_ctx *ctx;
87     void *resbuf;
88{
89  ((md5_uint32 *) resbuf)[0] = SWAP (ctx->A);
90  ((md5_uint32 *) resbuf)[1] = SWAP (ctx->B);
91  ((md5_uint32 *) resbuf)[2] = SWAP (ctx->C);
92  ((md5_uint32 *) resbuf)[3] = SWAP (ctx->D);
93
94  return resbuf;
95}
96
97/* Process the remaining bytes in the internal buffer and the usual
98   prolog according to the standard and write the result to RESBUF.
99
100   IMPORTANT: On some systems it is required that RESBUF is correctly
101   aligned for a 32 bits value.  */
102void *
103md5_finish_ctx (ctx, resbuf)
104     struct md5_ctx *ctx;
105     void *resbuf;
106{
107  /* Take yet unprocessed bytes into account.  */
108  md5_uint32 bytes = ctx->buflen;
109  size_t pad;
110
111  /* Now count remaining bytes.  */
112  ctx->total[0] += bytes;
113  if (ctx->total[0] < bytes)
114    ++ctx->total[1];
115
116  pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
117  memcpy (&ctx->buffer[bytes], fillbuf, pad);
118
119  /* Put the 64-bit file length in *bits* at the end of the buffer.  */
120  *(md5_uint32 *) &ctx->buffer[bytes + pad] = SWAP (ctx->total[0] << 3);
121  *(md5_uint32 *) &ctx->buffer[bytes + pad + 4] = SWAP ((ctx->total[1] << 3) |
122                            (ctx->total[0] >> 29));
123
124  /* Process last bytes.  */
125  md5_process_block (ctx->buffer, bytes + pad + 8, ctx);
126
127  return md5_read_ctx (ctx, resbuf);
128}
129
130/* Compute MD5 message digest for bytes read from STREAM.  The
131   resulting message digest number will be written into the 16 bytes
132   beginning at RESBLOCK.  */
133int
134md5_stream (stream, resblock)
135     FILE *stream;
136     void *resblock;
137{
138  /* Important: BLOCKSIZE must be a multiple of 64.  */
139#define BLOCKSIZE 4096
140  struct md5_ctx ctx;
141  char buffer[BLOCKSIZE + 72];
142  size_t sum;
143
144  /* Initialize the computation context.  */
145  md5_init_ctx (&ctx);
146
147  /* Iterate over full file contents.  */
148  while (1)
149    {
150      /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
151     computation function processes the whole buffer so that with the
152     next round of the loop another block can be read.  */
153      size_t n;
154      sum = 0;
155
156      /* Read block.  Take care for partial reads.  */
157      do
158    {
159      n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
160
161      sum += n;
162    }
163      while (sum < BLOCKSIZE && n != 0);
164      if (n == 0 && ferror (stream))
165        return 1;
166
167      /* If end of file is reached, end the loop.  */
168      if (n == 0)
169    break;
170
171      /* Process buffer with BLOCKSIZE bytes.  Note that
172            BLOCKSIZE % 64 == 0
173       */
174      md5_process_block (buffer, BLOCKSIZE, &ctx);
175    }
176
177  /* Add the last bytes if necessary.  */
178  if (sum > 0)
179    md5_process_bytes (buffer, sum, &ctx);
180
181  /* Construct result in desired memory.  */
182  md5_finish_ctx (&ctx, resblock);
183  return 0;
184}
185
186/* Compute MD5 message digest for LEN bytes beginning at BUFFER.  The
187   result is always in little endian byte order, so that a byte-wise
188   output yields to the wanted ASCII representation of the message
189   digest.  */
190void *
191md5_buffer (buffer, len, resblock)
192     const char *buffer;
193     size_t len;
194     void *resblock;
195{
196  struct md5_ctx ctx;
197
198  /* Initialize the computation context.  */
199  md5_init_ctx (&ctx);
200
201  /* Process whole buffer but last len % 64 bytes.  */
202  md5_process_bytes (buffer, len, &ctx);
203
204  /* Put result in desired memory area.  */
205  return md5_finish_ctx (&ctx, resblock);
206}
207
208
209void
210md5_process_bytes (buffer, len, ctx)
211     const void *buffer;
212     size_t len;
213     struct md5_ctx *ctx;
214{
215  /* When we already have some bits in our internal buffer concatenate
216     both inputs first.  */
217  if (ctx->buflen != 0)
218    {
219      size_t left_over = ctx->buflen;
220      size_t add = 128 - left_over > len ? len : 128 - left_over;
221
222      memcpy (&ctx->buffer[left_over], buffer, add);
223      ctx->buflen += add;
224
225      if (ctx->buflen > 64)
226    {
227      md5_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
228
229      ctx->buflen &= 63;
230      /* The regions in the following copy operation cannot overlap.  */
231      memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
232          ctx->buflen);
233    }
234
235      buffer = (const char *) buffer + add;
236      len -= add;
237    }
238
239  /* Process available complete blocks.  */
240  if (len >= 64)
241    {
242#if !_STRING_ARCH_unaligned
243/* To check alignment gcc has an appropriate operator.  Other
244   compilers don't.  */
245# if __GNUC__ >= 2
246#  define UNALIGNED_P(p) (((md5_uintptr) p) % __alignof__ (md5_uint32) != 0)
247# else
248#  define UNALIGNED_P(p) (((md5_uintptr) p) % sizeof (md5_uint32) != 0)
249# endif
250      if (UNALIGNED_P (buffer))
251    while (len > 64)
252      {
253        md5_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
254        buffer = (const char *) buffer + 64;
255        len -= 64;
256      }
257      else
258#endif
259    {
260      md5_process_block (buffer, len & ~63, ctx);
261      buffer = (const char *) buffer + (len & ~63);
262      len &= 63;
263    }
264    }
265
266  /* Move remaining bytes in internal buffer.  */
267  if (len > 0)
268    {
269      size_t left_over = ctx->buflen;
270
271      memcpy (&ctx->buffer[left_over], buffer, len);
272      left_over += len;
273      if (left_over >= 64)
274    {
275      md5_process_block (ctx->buffer, 64, ctx);
276      left_over -= 64;
277      memcpy (ctx->buffer, &ctx->buffer[64], left_over);
278    }
279      ctx->buflen = left_over;
280    }
281}
282
283
284/* These are the four functions used in the four steps of the MD5 algorithm
285   and defined in the RFC 1321.  The first function is a little bit optimized
286   (as found in Colin Plumbs public domain implementation).  */
287/* #define FF(b, c, d) ((b & c) | (~b & d)) */
288#define FF(b, c, d) (d ^ (b & (c ^ d)))
289#define FG(b, c, d) FF (d, b, c)
290#define FH(b, c, d) (b ^ c ^ d)
291#define FI(b, c, d) (c ^ (b | ~d))
292
293/* Process LEN bytes of BUFFER, accumulating context into CTX.
294   It is assumed that LEN % 64 == 0.  */
295
296void
297md5_process_block (buffer, len, ctx)
298     const void *buffer;
299     size_t len;
300     struct md5_ctx *ctx;
301{
302  md5_uint32 correct_words[16];
303  const md5_uint32 *words = buffer;
304  size_t nwords = len / sizeof (md5_uint32);
305  const md5_uint32 *endp = words + nwords;
306  md5_uint32 A = ctx->A;
307  md5_uint32 B = ctx->B;
308  md5_uint32 C = ctx->C;
309  md5_uint32 D = ctx->D;
310
311  /* First increment the byte count.  RFC 1321 specifies the possible
312     length of the file up to 2^64 bits.  Here we only compute the
313     number of bytes.  Do a double word increment.  */
314  ctx->total[0] += len;
315  if (ctx->total[0] < len)
316    ++ctx->total[1];
317
318  /* Process all bytes in the buffer with 64 bytes in each round of
319     the loop.  */
320  while (words < endp)
321    {
322      md5_uint32 *cwp = correct_words;
323      md5_uint32 A_save = A;
324      md5_uint32 B_save = B;
325      md5_uint32 C_save = C;
326      md5_uint32 D_save = D;
327
328      /* First round: using the given function, the context and a constant
329     the next context is computed.  Because the algorithms processing
330     unit is a 32-bit word and it is determined to work on words in
331     little endian byte order we perhaps have to change the byte order
332     before the computation.  To reduce the work for the next steps
333     we store the swapped words in the array CORRECT_WORDS.  */
334
335#define OP(a, b, c, d, s, T)                                            \
336      do                                                                \
337        {                                                               \
338      a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T;         \
339      ++words;                                                  \
340      CYCLIC (a, s);                                            \
341      a += b;                                                   \
342        }                                                               \
343      while (0)
344
345      /* It is unfortunate that C does not provide an operator for
346     cyclic rotation.  Hope the C compiler is smart enough.  */
347#define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s)))
348
349      /* Before we start, one word to the strange constants.
350     They are defined in RFC 1321 as
351
352     T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64
353       */
354
355      /* Round 1.  */
356      OP (A, B, C, D,  7, 0xd76aa478);
357      OP (D, A, B, C, 12, 0xe8c7b756);
358      OP (C, D, A, B, 17, 0x242070db);
359      OP (B, C, D, A, 22, 0xc1bdceee);
360      OP (A, B, C, D,  7, 0xf57c0faf);
361      OP (D, A, B, C, 12, 0x4787c62a);
362      OP (C, D, A, B, 17, 0xa8304613);
363      OP (B, C, D, A, 22, 0xfd469501);
364      OP (A, B, C, D,  7, 0x698098d8);
365      OP (D, A, B, C, 12, 0x8b44f7af);
366      OP (C, D, A, B, 17, 0xffff5bb1);
367      OP (B, C, D, A, 22, 0x895cd7be);
368      OP (A, B, C, D,  7, 0x6b901122);
369      OP (D, A, B, C, 12, 0xfd987193);
370      OP (C, D, A, B, 17, 0xa679438e);
371      OP (B, C, D, A, 22, 0x49b40821);
372
373      /* For the second to fourth round we have the possibly swapped words
374     in CORRECT_WORDS.  Redefine the macro to take an additional first
375     argument specifying the function to use.  */
376#undef OP
377#define OP(f, a, b, c, d, k, s, T)                                      \
378      do                                                                \
379    {                                                           \
380      a += f (b, c, d) + correct_words[k] + T;                  \
381      CYCLIC (a, s);                                            \
382      a += b;                                                   \
383    }                                                           \
384      while (0)
385
386      /* Round 2.  */
387      OP (FG, A, B, C, D,  1,  5, 0xf61e2562);
388      OP (FG, D, A, B, C,  6,  9, 0xc040b340);
389      OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
390      OP (FG, B, C, D, A,  0, 20, 0xe9b6c7aa);
391      OP (FG, A, B, C, D,  5,  5, 0xd62f105d);
392      OP (FG, D, A, B, C, 10,  9, 0x02441453);
393      OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
394      OP (FG, B, C, D, A,  4, 20, 0xe7d3fbc8);
395      OP (FG, A, B, C, D,  9,  5, 0x21e1cde6);
396      OP (FG, D, A, B, C, 14,  9, 0xc33707d6);
397      OP (FG, C, D, A, B,  3, 14, 0xf4d50d87);
398      OP (FG, B, C, D, A,  8, 20, 0x455a14ed);
399      OP (FG, A, B, C, D, 13,  5, 0xa9e3e905);
400      OP (FG, D, A, B, C,  2,  9, 0xfcefa3f8);
401      OP (FG, C, D, A, B,  7, 14, 0x676f02d9);
402      OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);
403
404      /* Round 3.  */
405      OP (FH, A, B, C, D,  5,  4, 0xfffa3942);
406      OP (FH, D, A, B, C,  8, 11, 0x8771f681);
407      OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
408      OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
409      OP (FH, A, B, C, D,  1,  4, 0xa4beea44);
410      OP (FH, D, A, B, C,  4, 11, 0x4bdecfa9);
411      OP (FH, C, D, A, B,  7, 16, 0xf6bb4b60);
412      OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
413      OP (FH, A, B, C, D, 13,  4, 0x289b7ec6);
414      OP (FH, D, A, B, C,  0, 11, 0xeaa127fa);
415      OP (FH, C, D, A, B,  3, 16, 0xd4ef3085);
416      OP (FH, B, C, D, A,  6, 23, 0x04881d05);
417      OP (FH, A, B, C, D,  9,  4, 0xd9d4d039);
418      OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
419      OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
420      OP (FH, B, C, D, A,  2, 23, 0xc4ac5665);
421
422      /* Round 4.  */
423      OP (FI, A, B, C, D,  0,  6, 0xf4292244);
424      OP (FI, D, A, B, C,  7, 10, 0x432aff97);
425      OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
426      OP (FI, B, C, D, A,  5, 21, 0xfc93a039);
427      OP (FI, A, B, C, D, 12,  6, 0x655b59c3);
428      OP (FI, D, A, B, C,  3, 10, 0x8f0ccc92);
429      OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
430      OP (FI, B, C, D, A,  1, 21, 0x85845dd1);
431      OP (FI, A, B, C, D,  8,  6, 0x6fa87e4f);
432      OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
433      OP (FI, C, D, A, B,  6, 15, 0xa3014314);
434      OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
435      OP (FI, A, B, C, D,  4,  6, 0xf7537e82);
436      OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
437      OP (FI, C, D, A, B,  2, 15, 0x2ad7d2bb);
438      OP (FI, B, C, D, A,  9, 21, 0xeb86d391);
439
440      /* Add the starting values of the context.  */
441      A += A_save;
442      B += B_save;
443      C += C_save;
444      D += D_save;
445    }
446
447  /* Put checksum in context given as argument.  */
448  ctx->A = A;
449  ctx->B = B;
450  ctx->C = C;
451  ctx->D = D;
452}
453