Backport 2010-05-27T04:24:30Z!handa@etlken from trunk
[emacs.git] / src / md5.c
blob37ae2e6acb5c210985ad09b56767bac19a0fd423
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, 2002, 2003, 2004,
4 2005, 2006, 2007 Free Software Foundation, Inc.
6 This file is part of the GNU C Library.
8 The GNU C Library is free software; you can redistribute it and/or
9 modify it under the terms of the GNU General Public License as
10 published by the Free Software Foundation; either version 2 of the
11 License, or (at your option) any later version.
13 The GNU C Library 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 GNU
16 General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with the GNU C Library; see the file COPYING. If not, write to the
20 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
21 Boston, MA 02110-1301, USA. */
23 /* Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995. */
25 #ifdef HAVE_CONFIG_H
26 # include <config.h>
27 #endif
29 #include <sys/types.h>
31 #if STDC_HEADERS || defined _LIBC
32 # include <stdlib.h>
33 # include <string.h>
34 #else
35 # ifndef HAVE_MEMCPY
36 # define memcpy(d, s, n) bcopy ((s), (d), (n))
37 # endif
38 #endif
40 #ifdef _LIBC
41 # include <endian.h>
42 # if __BYTE_ORDER == __BIG_ENDIAN
43 # define WORDS_BIG_ENDIAN 1
44 # endif
45 /* We need to keep the namespace clean so define the MD5 function
46 protected using leading __ . */
47 # define md5_init_ctx __md5_init_ctx
48 # define md5_process_block __md5_process_block
49 # define md5_process_bytes __md5_process_bytes
50 # define md5_finish_ctx __md5_finish_ctx
51 # define md5_read_ctx __md5_read_ctx
52 # define md5_stream __md5_stream
53 # define md5_buffer __md5_buffer
54 #endif
56 #include "md5.h"
58 #ifdef WORDS_BIG_ENDIAN
59 # define SWAP(n) \
60 (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
61 #else
62 # define SWAP(n) (n)
63 #endif
66 /* This array contains the bytes used to pad the buffer to the next
67 64-byte boundary. (RFC 1321, 3.1: Step 1) */
68 static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ... */ };
71 /* Initialize structure containing state of computation.
72 (RFC 1321, 3.3: Step 3) */
73 void
74 md5_init_ctx (ctx)
75 struct md5_ctx *ctx;
77 ctx->A = 0x67452301;
78 ctx->B = 0xefcdab89;
79 ctx->C = 0x98badcfe;
80 ctx->D = 0x10325476;
82 ctx->total[0] = ctx->total[1] = 0;
83 ctx->buflen = 0;
86 /* Put result from CTX in first 16 bytes following RESBUF. The result
87 must be in little endian byte order.
89 IMPORTANT: On some systems it is required that RESBUF is correctly
90 aligned for a 32 bits value. */
91 void *
92 md5_read_ctx (ctx, resbuf)
93 const struct md5_ctx *ctx;
94 void *resbuf;
96 ((md5_uint32 *) resbuf)[0] = SWAP (ctx->A);
97 ((md5_uint32 *) resbuf)[1] = SWAP (ctx->B);
98 ((md5_uint32 *) resbuf)[2] = SWAP (ctx->C);
99 ((md5_uint32 *) resbuf)[3] = SWAP (ctx->D);
101 return resbuf;
104 /* Process the remaining bytes in the internal buffer and the usual
105 prolog according to the standard and write the result to RESBUF.
107 IMPORTANT: On some systems it is required that RESBUF is correctly
108 aligned for a 32 bits value. */
109 void *
110 md5_finish_ctx (ctx, resbuf)
111 struct md5_ctx *ctx;
112 void *resbuf;
114 /* Take yet unprocessed bytes into account. */
115 md5_uint32 bytes = ctx->buflen;
116 size_t pad;
118 /* Now count remaining bytes. */
119 ctx->total[0] += bytes;
120 if (ctx->total[0] < bytes)
121 ++ctx->total[1];
123 pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
124 memcpy (&ctx->buffer[bytes], fillbuf, pad);
126 /* Put the 64-bit file length in *bits* at the end of the buffer. */
127 *(md5_uint32 *) &ctx->buffer[bytes + pad] = SWAP (ctx->total[0] << 3);
128 *(md5_uint32 *) &ctx->buffer[bytes + pad + 4] = SWAP ((ctx->total[1] << 3) |
129 (ctx->total[0] >> 29));
131 /* Process last bytes. */
132 md5_process_block (ctx->buffer, bytes + pad + 8, ctx);
134 return md5_read_ctx (ctx, resbuf);
137 /* Compute MD5 message digest for bytes read from STREAM. The
138 resulting message digest number will be written into the 16 bytes
139 beginning at RESBLOCK. */
141 md5_stream (stream, resblock)
142 FILE *stream;
143 void *resblock;
145 /* Important: BLOCKSIZE must be a multiple of 64. */
146 #define BLOCKSIZE 4096
147 struct md5_ctx ctx;
148 char buffer[BLOCKSIZE + 72];
149 size_t sum;
151 /* Initialize the computation context. */
152 md5_init_ctx (&ctx);
154 /* Iterate over full file contents. */
155 while (1)
157 /* We read the file in blocks of BLOCKSIZE bytes. One call of the
158 computation function processes the whole buffer so that with the
159 next round of the loop another block can be read. */
160 size_t n;
161 sum = 0;
163 /* Read block. Take care for partial reads. */
166 n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
168 sum += n;
170 while (sum < BLOCKSIZE && n != 0);
171 if (n == 0 && ferror (stream))
172 return 1;
174 /* If end of file is reached, end the loop. */
175 if (n == 0)
176 break;
178 /* Process buffer with BLOCKSIZE bytes. Note that
179 BLOCKSIZE % 64 == 0
181 md5_process_block (buffer, BLOCKSIZE, &ctx);
184 /* Add the last bytes if necessary. */
185 if (sum > 0)
186 md5_process_bytes (buffer, sum, &ctx);
188 /* Construct result in desired memory. */
189 md5_finish_ctx (&ctx, resblock);
190 return 0;
193 /* Compute MD5 message digest for LEN bytes beginning at BUFFER. The
194 result is always in little endian byte order, so that a byte-wise
195 output yields to the wanted ASCII representation of the message
196 digest. */
197 void *
198 md5_buffer (buffer, len, resblock)
199 const char *buffer;
200 size_t len;
201 void *resblock;
203 struct md5_ctx ctx;
205 /* Initialize the computation context. */
206 md5_init_ctx (&ctx);
208 /* Process whole buffer but last len % 64 bytes. */
209 md5_process_bytes (buffer, len, &ctx);
211 /* Put result in desired memory area. */
212 return md5_finish_ctx (&ctx, resblock);
216 void
217 md5_process_bytes (buffer, len, ctx)
218 const void *buffer;
219 size_t len;
220 struct md5_ctx *ctx;
222 /* const void aligned_buffer = buffer; */
224 /* When we already have some bits in our internal buffer concatenate
225 both inputs first. */
226 if (ctx->buflen != 0)
228 size_t left_over = ctx->buflen;
229 size_t add = 128 - left_over > len ? len : 128 - left_over;
231 /* Only put full words in the buffer. */
232 add -= add % __alignof__ (md5_uint32);
234 memcpy (&ctx->buffer[left_over], buffer, add);
235 ctx->buflen += add;
237 if (ctx->buflen > 64)
239 md5_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
241 ctx->buflen &= 63;
242 /* The regions in the following copy operation cannot overlap. */
243 memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
244 ctx->buflen);
247 buffer = (const char *) buffer + add;
248 len -= add;
251 /* Process available complete blocks. */
252 if (len > 64)
254 md5_process_block (buffer, len & ~63, ctx);
255 buffer = (const char *) buffer + (len & ~63);
256 len &= 63;
259 /* Move remaining bytes in internal buffer. */
260 if (len > 0)
262 size_t left_over = ctx->buflen;
264 memcpy (&ctx->buffer[left_over], buffer, len);
265 left_over += len;
266 if (left_over >= 64)
268 md5_process_block (ctx->buffer, 64, ctx);
269 left_over -= 64;
270 memcpy (ctx->buffer, &ctx->buffer[64], left_over);
272 ctx->buflen = left_over;
277 /* These are the four functions used in the four steps of the MD5 algorithm
278 and defined in the RFC 1321. The first function is a little bit optimized
279 (as found in Colin Plumbs public domain implementation). */
280 /* #define FF(b, c, d) ((b & c) | (~b & d)) */
281 #define FF(b, c, d) (d ^ (b & (c ^ d)))
282 #define FG(b, c, d) FF (d, b, c)
283 #define FH(b, c, d) (b ^ c ^ d)
284 #define FI(b, c, d) (c ^ (b | ~d))
286 /* Process LEN bytes of BUFFER, accumulating context into CTX.
287 It is assumed that LEN % 64 == 0. */
289 void
290 md5_process_block (buffer, len, ctx)
291 const void *buffer;
292 size_t len;
293 struct md5_ctx *ctx;
295 md5_uint32 correct_words[16];
296 const md5_uint32 *words = buffer;
297 size_t nwords = len / sizeof (md5_uint32);
298 const md5_uint32 *endp = words + nwords;
299 md5_uint32 A = ctx->A;
300 md5_uint32 B = ctx->B;
301 md5_uint32 C = ctx->C;
302 md5_uint32 D = ctx->D;
304 /* First increment the byte count. RFC 1321 specifies the possible
305 length of the file up to 2^64 bits. Here we only compute the
306 number of bytes. Do a double word increment. */
307 ctx->total[0] += len;
308 if (ctx->total[0] < len)
309 ++ctx->total[1];
311 /* Process all bytes in the buffer with 64 bytes in each round of
312 the loop. */
313 while (words < endp)
315 md5_uint32 *cwp = correct_words;
316 md5_uint32 A_save = A;
317 md5_uint32 B_save = B;
318 md5_uint32 C_save = C;
319 md5_uint32 D_save = D;
321 /* First round: using the given function, the context and a constant
322 the next context is computed. Because the algorithms processing
323 unit is a 32-bit word and it is determined to work on words in
324 little endian byte order we perhaps have to change the byte order
325 before the computation. To reduce the work for the next steps
326 we store the swapped words in the array CORRECT_WORDS. */
328 #define OP(a, b, c, d, s, T) \
329 do \
331 a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T; \
332 ++words; \
333 CYCLIC (a, s); \
334 a += b; \
336 while (0)
338 /* It is unfortunate that C does not provide an operator for
339 cyclic rotation. Hope the C compiler is smart enough. */
340 #define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s)))
342 /* Before we start, one word to the strange constants.
343 They are defined in RFC 1321 as
345 T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64
348 /* Round 1. */
349 OP (A, B, C, D, 7, 0xd76aa478);
350 OP (D, A, B, C, 12, 0xe8c7b756);
351 OP (C, D, A, B, 17, 0x242070db);
352 OP (B, C, D, A, 22, 0xc1bdceee);
353 OP (A, B, C, D, 7, 0xf57c0faf);
354 OP (D, A, B, C, 12, 0x4787c62a);
355 OP (C, D, A, B, 17, 0xa8304613);
356 OP (B, C, D, A, 22, 0xfd469501);
357 OP (A, B, C, D, 7, 0x698098d8);
358 OP (D, A, B, C, 12, 0x8b44f7af);
359 OP (C, D, A, B, 17, 0xffff5bb1);
360 OP (B, C, D, A, 22, 0x895cd7be);
361 OP (A, B, C, D, 7, 0x6b901122);
362 OP (D, A, B, C, 12, 0xfd987193);
363 OP (C, D, A, B, 17, 0xa679438e);
364 OP (B, C, D, A, 22, 0x49b40821);
366 /* For the second to fourth round we have the possibly swapped words
367 in CORRECT_WORDS. Redefine the macro to take an additional first
368 argument specifying the function to use. */
369 #undef OP
370 #define OP(f, a, b, c, d, k, s, T) \
371 do \
373 a += f (b, c, d) + correct_words[k] + T; \
374 CYCLIC (a, s); \
375 a += b; \
377 while (0)
379 /* Round 2. */
380 OP (FG, A, B, C, D, 1, 5, 0xf61e2562);
381 OP (FG, D, A, B, C, 6, 9, 0xc040b340);
382 OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
383 OP (FG, B, C, D, A, 0, 20, 0xe9b6c7aa);
384 OP (FG, A, B, C, D, 5, 5, 0xd62f105d);
385 OP (FG, D, A, B, C, 10, 9, 0x02441453);
386 OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
387 OP (FG, B, C, D, A, 4, 20, 0xe7d3fbc8);
388 OP (FG, A, B, C, D, 9, 5, 0x21e1cde6);
389 OP (FG, D, A, B, C, 14, 9, 0xc33707d6);
390 OP (FG, C, D, A, B, 3, 14, 0xf4d50d87);
391 OP (FG, B, C, D, A, 8, 20, 0x455a14ed);
392 OP (FG, A, B, C, D, 13, 5, 0xa9e3e905);
393 OP (FG, D, A, B, C, 2, 9, 0xfcefa3f8);
394 OP (FG, C, D, A, B, 7, 14, 0x676f02d9);
395 OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);
397 /* Round 3. */
398 OP (FH, A, B, C, D, 5, 4, 0xfffa3942);
399 OP (FH, D, A, B, C, 8, 11, 0x8771f681);
400 OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
401 OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
402 OP (FH, A, B, C, D, 1, 4, 0xa4beea44);
403 OP (FH, D, A, B, C, 4, 11, 0x4bdecfa9);
404 OP (FH, C, D, A, B, 7, 16, 0xf6bb4b60);
405 OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
406 OP (FH, A, B, C, D, 13, 4, 0x289b7ec6);
407 OP (FH, D, A, B, C, 0, 11, 0xeaa127fa);
408 OP (FH, C, D, A, B, 3, 16, 0xd4ef3085);
409 OP (FH, B, C, D, A, 6, 23, 0x04881d05);
410 OP (FH, A, B, C, D, 9, 4, 0xd9d4d039);
411 OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
412 OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
413 OP (FH, B, C, D, A, 2, 23, 0xc4ac5665);
415 /* Round 4. */
416 OP (FI, A, B, C, D, 0, 6, 0xf4292244);
417 OP (FI, D, A, B, C, 7, 10, 0x432aff97);
418 OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
419 OP (FI, B, C, D, A, 5, 21, 0xfc93a039);
420 OP (FI, A, B, C, D, 12, 6, 0x655b59c3);
421 OP (FI, D, A, B, C, 3, 10, 0x8f0ccc92);
422 OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
423 OP (FI, B, C, D, A, 1, 21, 0x85845dd1);
424 OP (FI, A, B, C, D, 8, 6, 0x6fa87e4f);
425 OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
426 OP (FI, C, D, A, B, 6, 15, 0xa3014314);
427 OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
428 OP (FI, A, B, C, D, 4, 6, 0xf7537e82);
429 OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
430 OP (FI, C, D, A, B, 2, 15, 0x2ad7d2bb);
431 OP (FI, B, C, D, A, 9, 21, 0xeb86d391);
433 /* Add the starting values of the context. */
434 A += A_save;
435 B += B_save;
436 C += C_save;
437 D += D_save;
440 /* Put checksum in context given as argument. */
441 ctx->A = A;
442 ctx->B = B;
443 ctx->C = C;
444 ctx->D = D;
447 /* arch-tag: 60084f04-b434-42cb-9d2b-e91df01f4325
448 (do not change this comment) */