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) 1995-2023 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: 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. */
81 void *
82 md5_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. */
101 void *
102 md5_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. */
134 int
135 md5_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. */
189 void *
190 md5_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
205 void
206 md5_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 || defined UBSAN_BOOTSTRAP
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
280 void
281 md5_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 }