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author kent <kent@cr.ie.u-ryukyu.ac.jp>
date Fri, 17 Jul 2009 14:47:48 +0900
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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) */
59 static 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) */
64 void
65 md5_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. */
81 void *
82 md5_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. */
97 void *
98 md5_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. */
126 int
127 md5_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. */
181 void *
182 md5_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
197 void
198 md5_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 memcpy (ctx->buffer, buffer, 64);
238 md5_process_block (ctx->buffer, 64, ctx);
239 buffer = (const char *) buffer + 64;
240 len -= 64;
241 }
242 else
243 #endif
244 md5_process_block (buffer, len & ~63, ctx);
245 buffer = (const void *) ((const char *) buffer + (len & ~63));
246 len &= 63;
247 }
248
249 /* Move remaining bytes in internal buffer. */
250 if (len > 0)
251 {
252 memcpy (ctx->buffer, buffer, len);
253 ctx->buflen = len;
254 }
255 }
256
257
258 /* These are the four functions used in the four steps of the MD5 algorithm
259 and defined in the RFC 1321. The first function is a little bit optimized
260 (as found in Colin Plumbs public domain implementation). */
261 /* #define FF(b, c, d) ((b & c) | (~b & d)) */
262 #define FF(b, c, d) (d ^ (b & (c ^ d)))
263 #define FG(b, c, d) FF (d, b, c)
264 #define FH(b, c, d) (b ^ c ^ d)
265 #define FI(b, c, d) (c ^ (b | ~d))
266
267 /* Process LEN bytes of BUFFER, accumulating context into CTX.
268 It is assumed that LEN % 64 == 0. */
269
270 void
271 md5_process_block (const void *buffer, size_t len, struct md5_ctx *ctx)
272 {
273 md5_uint32 correct_words[16];
274 const md5_uint32 *words = (const md5_uint32 *) buffer;
275 size_t nwords = len / sizeof (md5_uint32);
276 const md5_uint32 *endp = words + nwords;
277 md5_uint32 A = ctx->A;
278 md5_uint32 B = ctx->B;
279 md5_uint32 C = ctx->C;
280 md5_uint32 D = ctx->D;
281
282 /* First increment the byte count. RFC 1321 specifies the possible
283 length of the file up to 2^64 bits. Here we only compute the
284 number of bytes. Do a double word increment. */
285 ctx->total[0] += len;
286 if (ctx->total[0] < len)
287 ++ctx->total[1];
288
289 /* Process all bytes in the buffer with 64 bytes in each round of
290 the loop. */
291 while (words < endp)
292 {
293 md5_uint32 *cwp = correct_words;
294 md5_uint32 A_save = A;
295 md5_uint32 B_save = B;
296 md5_uint32 C_save = C;
297 md5_uint32 D_save = D;
298
299 /* First round: using the given function, the context and a constant
300 the next context is computed. Because the algorithms processing
301 unit is a 32-bit word and it is determined to work on words in
302 little endian byte order we perhaps have to change the byte order
303 before the computation. To reduce the work for the next steps
304 we store the swapped words in the array CORRECT_WORDS. */
305
306 #define OP(a, b, c, d, s, T) \
307 do \
308 { \
309 a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T; \
310 ++words; \
311 CYCLIC (a, s); \
312 a += b; \
313 } \
314 while (0)
315
316 /* It is unfortunate that C does not provide an operator for
317 cyclic rotation. Hope the C compiler is smart enough. */
318 #define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s)))
319
320 /* Before we start, one word to the strange constants.
321 They are defined in RFC 1321 as
322
323 T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64
324 */
325
326 /* Round 1. */
327 OP (A, B, C, D, 7, (md5_uint32) 0xd76aa478);
328 OP (D, A, B, C, 12, (md5_uint32) 0xe8c7b756);
329 OP (C, D, A, B, 17, (md5_uint32) 0x242070db);
330 OP (B, C, D, A, 22, (md5_uint32) 0xc1bdceee);
331 OP (A, B, C, D, 7, (md5_uint32) 0xf57c0faf);
332 OP (D, A, B, C, 12, (md5_uint32) 0x4787c62a);
333 OP (C, D, A, B, 17, (md5_uint32) 0xa8304613);
334 OP (B, C, D, A, 22, (md5_uint32) 0xfd469501);
335 OP (A, B, C, D, 7, (md5_uint32) 0x698098d8);
336 OP (D, A, B, C, 12, (md5_uint32) 0x8b44f7af);
337 OP (C, D, A, B, 17, (md5_uint32) 0xffff5bb1);
338 OP (B, C, D, A, 22, (md5_uint32) 0x895cd7be);
339 OP (A, B, C, D, 7, (md5_uint32) 0x6b901122);
340 OP (D, A, B, C, 12, (md5_uint32) 0xfd987193);
341 OP (C, D, A, B, 17, (md5_uint32) 0xa679438e);
342 OP (B, C, D, A, 22, (md5_uint32) 0x49b40821);
343
344 /* For the second to fourth round we have the possibly swapped words
345 in CORRECT_WORDS. Redefine the macro to take an additional first
346 argument specifying the function to use. */
347 #undef OP
348 #define OP(a, b, c, d, k, s, T) \
349 do \
350 { \
351 a += FX (b, c, d) + correct_words[k] + T; \
352 CYCLIC (a, s); \
353 a += b; \
354 } \
355 while (0)
356
357 #define FX(b, c, d) FG (b, c, d)
358
359 /* Round 2. */
360 OP (A, B, C, D, 1, 5, (md5_uint32) 0xf61e2562);
361 OP (D, A, B, C, 6, 9, (md5_uint32) 0xc040b340);
362 OP (C, D, A, B, 11, 14, (md5_uint32) 0x265e5a51);
363 OP (B, C, D, A, 0, 20, (md5_uint32) 0xe9b6c7aa);
364 OP (A, B, C, D, 5, 5, (md5_uint32) 0xd62f105d);
365 OP (D, A, B, C, 10, 9, (md5_uint32) 0x02441453);
366 OP (C, D, A, B, 15, 14, (md5_uint32) 0xd8a1e681);
367 OP (B, C, D, A, 4, 20, (md5_uint32) 0xe7d3fbc8);
368 OP (A, B, C, D, 9, 5, (md5_uint32) 0x21e1cde6);
369 OP (D, A, B, C, 14, 9, (md5_uint32) 0xc33707d6);
370 OP (C, D, A, B, 3, 14, (md5_uint32) 0xf4d50d87);
371 OP (B, C, D, A, 8, 20, (md5_uint32) 0x455a14ed);
372 OP (A, B, C, D, 13, 5, (md5_uint32) 0xa9e3e905);
373 OP (D, A, B, C, 2, 9, (md5_uint32) 0xfcefa3f8);
374 OP (C, D, A, B, 7, 14, (md5_uint32) 0x676f02d9);
375 OP (B, C, D, A, 12, 20, (md5_uint32) 0x8d2a4c8a);
376
377 #undef FX
378 #define FX(b, c, d) FH (b, c, d)
379
380 /* Round 3. */
381 OP (A, B, C, D, 5, 4, (md5_uint32) 0xfffa3942);
382 OP (D, A, B, C, 8, 11, (md5_uint32) 0x8771f681);
383 OP (C, D, A, B, 11, 16, (md5_uint32) 0x6d9d6122);
384 OP (B, C, D, A, 14, 23, (md5_uint32) 0xfde5380c);
385 OP (A, B, C, D, 1, 4, (md5_uint32) 0xa4beea44);
386 OP (D, A, B, C, 4, 11, (md5_uint32) 0x4bdecfa9);
387 OP (C, D, A, B, 7, 16, (md5_uint32) 0xf6bb4b60);
388 OP (B, C, D, A, 10, 23, (md5_uint32) 0xbebfbc70);
389 OP (A, B, C, D, 13, 4, (md5_uint32) 0x289b7ec6);
390 OP (D, A, B, C, 0, 11, (md5_uint32) 0xeaa127fa);
391 OP (C, D, A, B, 3, 16, (md5_uint32) 0xd4ef3085);
392 OP (B, C, D, A, 6, 23, (md5_uint32) 0x04881d05);
393 OP (A, B, C, D, 9, 4, (md5_uint32) 0xd9d4d039);
394 OP (D, A, B, C, 12, 11, (md5_uint32) 0xe6db99e5);
395 OP (C, D, A, B, 15, 16, (md5_uint32) 0x1fa27cf8);
396 OP (B, C, D, A, 2, 23, (md5_uint32) 0xc4ac5665);
397
398 #undef FX
399 #define FX(b, c, d) FI (b, c, d)
400
401 /* Round 4. */
402 OP (A, B, C, D, 0, 6, (md5_uint32) 0xf4292244);
403 OP (D, A, B, C, 7, 10, (md5_uint32) 0x432aff97);
404 OP (C, D, A, B, 14, 15, (md5_uint32) 0xab9423a7);
405 OP (B, C, D, A, 5, 21, (md5_uint32) 0xfc93a039);
406 OP (A, B, C, D, 12, 6, (md5_uint32) 0x655b59c3);
407 OP (D, A, B, C, 3, 10, (md5_uint32) 0x8f0ccc92);
408 OP (C, D, A, B, 10, 15, (md5_uint32) 0xffeff47d);
409 OP (B, C, D, A, 1, 21, (md5_uint32) 0x85845dd1);
410 OP (A, B, C, D, 8, 6, (md5_uint32) 0x6fa87e4f);
411 OP (D, A, B, C, 15, 10, (md5_uint32) 0xfe2ce6e0);
412 OP (C, D, A, B, 6, 15, (md5_uint32) 0xa3014314);
413 OP (B, C, D, A, 13, 21, (md5_uint32) 0x4e0811a1);
414 OP (A, B, C, D, 4, 6, (md5_uint32) 0xf7537e82);
415 OP (D, A, B, C, 11, 10, (md5_uint32) 0xbd3af235);
416 OP (C, D, A, B, 2, 15, (md5_uint32) 0x2ad7d2bb);
417 OP (B, C, D, A, 9, 21, (md5_uint32) 0xeb86d391);
418
419 /* Add the starting values of the context. */
420 A += A_save;
421 B += B_save;
422 C += C_save;
423 D += D_save;
424 }
425
426 /* Put checksum in context given as argument. */
427 ctx->A = A;
428 ctx->B = B;
429 ctx->C = C;
430 ctx->D = D;
431 }