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 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library.
18 If not, see <https://www.gnu.org/licenses/>. */
19
20 /* Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995. */
21
22 #ifdef HAVE_CONFIG_H
23 # include <config.h>
24 #endif
25
26 #include <sys/types.h>
27
28 #include <stdlib.h>
29 #include <string.h>
30
31 #include "md5.h"
32
33 #ifdef _LIBC
34 # include <endian.h>
35 # if __BYTE_ORDER == __BIG_ENDIAN
36 # define WORDS_BIGENDIAN 1
37 # endif
38 /* We need to keep the namespace clean so define the MD5 function
39 protected using leading __ . */
40 # define md5_init_ctx __md5_init_ctx
41 # define md5_process_block __md5_process_block
42 # define md5_process_bytes __md5_process_bytes
43 # define md5_finish_ctx __md5_finish_ctx
44 # define md5_read_ctx __md5_read_ctx
45 # define md5_stream __md5_stream
46 # define md5_buffer __md5_buffer
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 void
63 md5_init_ctx (struct md5_ctx *ctx);
64 void *
65 md5_read_ctx (const struct md5_ctx *ctx, void *resbuf);
66 void *
67 md5_finish_ctx (struct md5_ctx *ctx, void *resbuf);
68 int
69 md5_stream (FILE *stream, void *resblock);
70 void *
71 md5_buffer (const char *buffer, size_t len, void *resblock);
72 void
73 md5_process_bytes (const void *buffer, size_t len, struct md5_ctx *ctx);
74 void
75 md5_process_block (const void *buffer, size_t len, struct md5_ctx *ctx);
76
77
78 /* Initialize structure containing state of computation.
79 (RFC 1321, 3.3: Step 3) */
80 void
md5_init_ctx(struct md5_ctx *ctx)81 md5_init_ctx (struct md5_ctx *ctx)
82 {
83 ctx->A = 0x67452301;
84 ctx->B = 0xefcdab89;
85 ctx->C = 0x98badcfe;
86 ctx->D = 0x10325476;
87
88 ctx->total[0] = ctx->total[1] = 0;
89 ctx->buflen = 0;
90 }
91
92 /* Put result from CTX in first 16 bytes following RESBUF. The result
93 must be in little endian byte order.
94
95 IMPORTANT: On some systems it is required that RESBUF is correctly
96 aligned for a 32 bits value. */
97 void *
md5_read_ctx(const struct md5_ctx *ctx, void *resbuf)98 md5_read_ctx (const struct md5_ctx *ctx, void *resbuf)
99 {
100 ((md5_uint32 *) resbuf)[0] = SWAP (ctx->A);
101 ((md5_uint32 *) resbuf)[1] = SWAP (ctx->B);
102 ((md5_uint32 *) resbuf)[2] = SWAP (ctx->C);
103 ((md5_uint32 *) resbuf)[3] = SWAP (ctx->D);
104
105 return resbuf;
106 }
107
108 /* Process the remaining bytes in the internal buffer and the usual
109 prolog according to the standard and write the result to RESBUF.
110
111 IMPORTANT: On some systems it is required that RESBUF is correctly
112 aligned for a 32 bits value. */
113 void *
md5_finish_ctx(struct md5_ctx *ctx, void *resbuf)114 md5_finish_ctx (struct md5_ctx *ctx, void *resbuf)
115 {
116 /* Take yet unprocessed bytes into account. */
117 md5_uint32 bytes = ctx->buflen;
118 size_t pad;
119 size_t offset;
120
121 /* Now count remaining bytes. */
122 ctx->total[0] += bytes;
123 if (ctx->total[0] < bytes)
124 ++ctx->total[1];
125
126 pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
127 memcpy (&ctx->buffer[bytes], fillbuf, pad);
128
129 /* Put the 64-bit file length in *bits* at the end of the buffer. */
130 offset = (bytes + pad) / sizeof (md5_uint32);
131 ((md5_uint32 *) ctx->buffer)[offset] = SWAP (ctx->total[0] << 3);
132 offset = (bytes + pad + 4) / sizeof (md5_uint32);
133 ((md5_uint32 *) ctx->buffer)[offset] = SWAP ((ctx->total[1] << 3) |
134 (ctx->total[0] >> 29));
135
136 /* Process last bytes. */
137 md5_process_block (ctx->buffer, bytes + pad + 8, ctx);
138
139 return md5_read_ctx (ctx, resbuf);
140 }
141
142 /* Compute MD5 message digest for bytes read from STREAM. The
143 resulting message digest number will be written into the 16 bytes
144 beginning at RESBLOCK. */
145 int
md5_stream(FILE *stream, void *resblock)146 md5_stream (FILE *stream, void *resblock)
147 {
148 /* Important: BLOCKSIZE must be a multiple of 64. */
149 #define BLOCKSIZE 4096
150 struct md5_ctx ctx;
151 char buffer[BLOCKSIZE + 72];
152 size_t sum;
153
154 /* Initialize the computation context. */
155 md5_init_ctx (&ctx);
156
157 /* Iterate over full file contents. */
158 while (1)
159 {
160 /* We read the file in blocks of BLOCKSIZE bytes. One call of the
161 computation function processes the whole buffer so that with the
162 next round of the loop another block can be read. */
163 size_t n;
164 sum = 0;
165
166 /* Read block. Take care for partial reads. */
167 do
168 {
169 n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
170
171 sum += n;
172 }
173 while (sum < BLOCKSIZE && n != 0);
174 if (n == 0 && ferror (stream))
175 return 1;
176
177 /* If end of file is reached, end the loop. */
178 if (n == 0)
179 break;
180
181 /* Process buffer with BLOCKSIZE bytes. Note that
182 BLOCKSIZE % 64 == 0
183 */
184 md5_process_block (buffer, BLOCKSIZE, &ctx);
185 }
186
187 /* Add the last bytes if necessary. */
188 if (sum > 0)
189 md5_process_bytes (buffer, sum, &ctx);
190
191 /* Construct result in desired memory. */
192 md5_finish_ctx (&ctx, resblock);
193 return 0;
194 }
195
196 /* Compute MD5 message digest for LEN bytes beginning at BUFFER. The
197 result is always in little endian byte order, so that a byte-wise
198 output yields to the wanted ASCII representation of the message
199 digest. */
200 void *
md5_buffer(const char *buffer, size_t len, void *resblock)201 md5_buffer (const char *buffer, size_t len, void *resblock)
202 {
203 struct md5_ctx ctx;
204
205 /* Initialize the computation context. */
206 md5_init_ctx (&ctx);
207
208 /* Process whole buffer but last len % 64 bytes. */
209 md5_process_bytes (buffer, len, &ctx);
210
211 /* Put result in desired memory area. */
212 return md5_finish_ctx (&ctx, resblock);
213 }
214
215
216 void
md5_process_bytes(const void *buffer, size_t len, struct md5_ctx *ctx)217 md5_process_bytes (const void *buffer, size_t len, struct md5_ctx *ctx)
218 {
219 /* When we already have some bits in our internal buffer concatenate
220 both inputs first. */
221 if (ctx->buflen != 0)
222 {
223 size_t left_over = ctx->buflen;
224 size_t add = 128 - left_over > len ? len : 128 - left_over;
225
226 memcpy (&ctx->buffer[left_over], buffer, add);
227 ctx->buflen += add;
228
229 if (ctx->buflen > 64)
230 {
231 md5_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
232
233 ctx->buflen &= 63;
234 /* The regions in the following copy operation cannot overlap. */
235 memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
236 ctx->buflen);
237 }
238
239 buffer = (const char *) buffer + add;
240 len -= add;
241 }
242
243 /* Process available complete blocks. */
244 if (len >= 64)
245 {
246 #if !_STRING_ARCH_unaligned
247 /* To check alignment gcc has an appropriate operator. Other
248 compilers don't. */
249 # if __GNUC__ >= 2
250 # define UNALIGNED_P(p) (((md5_uintptr) p) % __alignof__ (md5_uint32) != 0)
251 # else
252 # define UNALIGNED_P(p) (((md5_uintptr) p) % sizeof (md5_uint32) != 0)
253 # endif
254 if (UNALIGNED_P (buffer))
255 while (len > 64)
256 {
257 md5_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
258 buffer = (const char *) buffer + 64;
259 len -= 64;
260 }
261 else
262 #endif
263 {
264 md5_process_block (buffer, len & ~63, ctx);
265 buffer = (const char *) buffer + (len & ~63);
266 len &= 63;
267 }
268 }
269
270 /* Move remaining bytes in internal buffer. */
271 if (len > 0)
272 {
273 size_t left_over = ctx->buflen;
274
275 memcpy (&ctx->buffer[left_over], buffer, len);
276 left_over += len;
277 if (left_over >= 64)
278 {
279 md5_process_block (ctx->buffer, 64, ctx);
280 left_over -= 64;
281 memcpy (ctx->buffer, &ctx->buffer[64], left_over);
282 }
283 ctx->buflen = left_over;
284 }
285 }
286
287
288 /* These are the four functions used in the four steps of the MD5 algorithm
289 and defined in the RFC 1321. The first function is a little bit optimized
290 (as found in Colin Plumbs public domain implementation). */
291 /* #define FF(b, c, d) ((b & c) | (~b & d)) */
292 #define FF(b, c, d) (d ^ (b & (c ^ d)))
293 #define FG(b, c, d) FF (d, b, c)
294 #define FH(b, c, d) (b ^ c ^ d)
295 #define FI(b, c, d) (c ^ (b | ~d))
296
297 /* Process LEN bytes of BUFFER, accumulating context into CTX.
298 It is assumed that LEN % 64 == 0. */
299
300 void
md5_process_block(const void *buffer, size_t len, struct md5_ctx *ctx)301 md5_process_block (const void *buffer, size_t len, struct md5_ctx *ctx)
302 {
303 md5_uint32 correct_words[16];
304 const md5_uint32 *words = buffer;
305 size_t nwords = len / sizeof (md5_uint32);
306 const md5_uint32 *endp = words + nwords;
307 md5_uint32 A = ctx->A;
308 md5_uint32 B = ctx->B;
309 md5_uint32 C = ctx->C;
310 md5_uint32 D = ctx->D;
311
312 /* First increment the byte count. RFC 1321 specifies the possible
313 length of the file up to 2^64 bits. Here we only compute the
314 number of bytes. Do a double word increment. */
315 ctx->total[0] += len;
316 if (ctx->total[0] < len)
317 ++ctx->total[1];
318
319 /* Process all bytes in the buffer with 64 bytes in each round of
320 the loop. */
321 while (words < endp)
322 {
323 md5_uint32 *cwp = correct_words;
324 md5_uint32 A_save = A;
325 md5_uint32 B_save = B;
326 md5_uint32 C_save = C;
327 md5_uint32 D_save = D;
328
329 /* First round: using the given function, the context and a constant
330 the next context is computed. Because the algorithms processing
331 unit is a 32-bit word and it is determined to work on words in
332 little endian byte order we perhaps have to change the byte order
333 before the computation. To reduce the work for the next steps
334 we store the swapped words in the array CORRECT_WORDS. */
335
336 #define OP(a, b, c, d, s, T) \
337 do \
338 { \
339 a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T; \
340 ++words; \
341 CYCLIC (a, s); \
342 a += b; \
343 } \
344 while (0)
345
346 /* It is unfortunate that C does not provide an operator for
347 cyclic rotation. Hope the C compiler is smart enough. */
348 #define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s)))
349
350 /* Before we start, one word to the strange constants.
351 They are defined in RFC 1321 as
352
353 T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64
354 */
355
356 /* Round 1. */
357 OP (A, B, C, D, 7, 0xd76aa478);
358 OP (D, A, B, C, 12, 0xe8c7b756);
359 OP (C, D, A, B, 17, 0x242070db);
360 OP (B, C, D, A, 22, 0xc1bdceee);
361 OP (A, B, C, D, 7, 0xf57c0faf);
362 OP (D, A, B, C, 12, 0x4787c62a);
363 OP (C, D, A, B, 17, 0xa8304613);
364 OP (B, C, D, A, 22, 0xfd469501);
365 OP (A, B, C, D, 7, 0x698098d8);
366 OP (D, A, B, C, 12, 0x8b44f7af);
367 OP (C, D, A, B, 17, 0xffff5bb1);
368 OP (B, C, D, A, 22, 0x895cd7be);
369 OP (A, B, C, D, 7, 0x6b901122);
370 OP (D, A, B, C, 12, 0xfd987193);
371 OP (C, D, A, B, 17, 0xa679438e);
372 OP (B, C, D, A, 22, 0x49b40821);
373
374 /* For the second to fourth round we have the possibly swapped words
375 in CORRECT_WORDS. Redefine the macro to take an additional first
376 argument specifying the function to use. */
377 #undef OP
378 #define OP(f, a, b, c, d, k, s, T) \
379 do \
380 { \
381 a += f (b, c, d) + correct_words[k] + T; \
382 CYCLIC (a, s); \
383 a += b; \
384 } \
385 while (0)
386
387 /* Round 2. */
388 OP (FG, A, B, C, D, 1, 5, 0xf61e2562);
389 OP (FG, D, A, B, C, 6, 9, 0xc040b340);
390 OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
391 OP (FG, B, C, D, A, 0, 20, 0xe9b6c7aa);
392 OP (FG, A, B, C, D, 5, 5, 0xd62f105d);
393 OP (FG, D, A, B, C, 10, 9, 0x02441453);
394 OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
395 OP (FG, B, C, D, A, 4, 20, 0xe7d3fbc8);
396 OP (FG, A, B, C, D, 9, 5, 0x21e1cde6);
397 OP (FG, D, A, B, C, 14, 9, 0xc33707d6);
398 OP (FG, C, D, A, B, 3, 14, 0xf4d50d87);
399 OP (FG, B, C, D, A, 8, 20, 0x455a14ed);
400 OP (FG, A, B, C, D, 13, 5, 0xa9e3e905);
401 OP (FG, D, A, B, C, 2, 9, 0xfcefa3f8);
402 OP (FG, C, D, A, B, 7, 14, 0x676f02d9);
403 OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);
404
405 /* Round 3. */
406 OP (FH, A, B, C, D, 5, 4, 0xfffa3942);
407 OP (FH, D, A, B, C, 8, 11, 0x8771f681);
408 OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
409 OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
410 OP (FH, A, B, C, D, 1, 4, 0xa4beea44);
411 OP (FH, D, A, B, C, 4, 11, 0x4bdecfa9);
412 OP (FH, C, D, A, B, 7, 16, 0xf6bb4b60);
413 OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
414 OP (FH, A, B, C, D, 13, 4, 0x289b7ec6);
415 OP (FH, D, A, B, C, 0, 11, 0xeaa127fa);
416 OP (FH, C, D, A, B, 3, 16, 0xd4ef3085);
417 OP (FH, B, C, D, A, 6, 23, 0x04881d05);
418 OP (FH, A, B, C, D, 9, 4, 0xd9d4d039);
419 OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
420 OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
421 OP (FH, B, C, D, A, 2, 23, 0xc4ac5665);
422
423 /* Round 4. */
424 OP (FI, A, B, C, D, 0, 6, 0xf4292244);
425 OP (FI, D, A, B, C, 7, 10, 0x432aff97);
426 OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
427 OP (FI, B, C, D, A, 5, 21, 0xfc93a039);
428 OP (FI, A, B, C, D, 12, 6, 0x655b59c3);
429 OP (FI, D, A, B, C, 3, 10, 0x8f0ccc92);
430 OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
431 OP (FI, B, C, D, A, 1, 21, 0x85845dd1);
432 OP (FI, A, B, C, D, 8, 6, 0x6fa87e4f);
433 OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
434 OP (FI, C, D, A, B, 6, 15, 0xa3014314);
435 OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
436 OP (FI, A, B, C, D, 4, 6, 0xf7537e82);
437 OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
438 OP (FI, C, D, A, B, 2, 15, 0x2ad7d2bb);
439 OP (FI, B, C, D, A, 9, 21, 0xeb86d391);
440
441 /* Add the starting values of the context. */
442 A += A_save;
443 B += B_save;
444 C += C_save;
445 D += D_save;
446 }
447
448 /* Put checksum in context given as argument. */
449 ctx->A = A;
450 ctx->B = B;
451 ctx->C = C;
452 ctx->D = D;
453 }
454