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, 2001, 2003, 2004, 2005 Free Software Foundation, Inc.
4 NOTE: The canonical source of this file is maintained with the GNU C
5 Library. Bugs can be reported to bug-glibc@prep.ai.mit.edu.
6
7 This program is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by the
9 Free Software Foundation; either version 2, or (at your option) any
10 later version.
11
12 This program 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
15 GNU General Public License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, write to the Free Software Foundation,
19 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
20 #include <sys/cdefs.h>
21 __RCSID("$NetBSD: md5.c,v 1.2 2016/05/17 14:00:09 christos Exp $");
22
23
24 /* Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995. */
25
26 #ifdef HAVE_CONFIG_H
27 # include <config.h>
28 #endif
29
30 #include "md5.h"
31
32 #include <stddef.h>
33 #include <string.h>
34
35 #if USE_UNLOCKED_IO
36 # include "unlocked-io.h"
37 #endif
38
39 #ifdef _LIBC
40 # include <endian.h>
41 # if __BYTE_ORDER == __BIG_ENDIAN
42 # define WORDS_BIGENDIAN 1
43 # endif
44 /* We need to keep the namespace clean so define the MD5 function
45 protected using leading __ . */
46 # define md5_init_ctx __md5_init_ctx
47 # define md5_process_block __md5_process_block
48 # define md5_process_bytes __md5_process_bytes
49 # define md5_finish_ctx __md5_finish_ctx
50 # define md5_read_ctx __md5_read_ctx
51 # define md5_stream __md5_stream
52 # define md5_buffer __md5_buffer
53 #endif
54
55 #ifdef WORDS_BIGENDIAN
56 # define SWAP(n) \
57 (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
58 #else
59 # define SWAP(n) (n)
60 #endif
61
62 #define BLOCKSIZE 4096
63 #if BLOCKSIZE % 64 != 0
64 # error "invalid BLOCKSIZE"
65 #endif
66
67 /* This array contains the bytes used to pad the buffer to the next
68 64-byte boundary. (RFC 1321, 3.1: Step 1) */
69 static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ... */ };
70
71
72 /* Initialize structure containing state of computation.
73 (RFC 1321, 3.3: Step 3) */
74 void
md5_init_ctx(struct md5_ctx * ctx)75 md5_init_ctx (struct md5_ctx *ctx)
76 {
77 ctx->A = 0x67452301;
78 ctx->B = 0xefcdab89;
79 ctx->C = 0x98badcfe;
80 ctx->D = 0x10325476;
81
82 ctx->total[0] = ctx->total[1] = 0;
83 ctx->buflen = 0;
84 }
85
86 /* Put result from CTX in first 16 bytes following RESBUF. The result
87 must be in little endian byte order.
88
89 IMPORTANT: On some systems it is required that RESBUF is correctly
90 aligned for a 32 bits value. */
91 void *
md5_read_ctx(const struct md5_ctx * ctx,void * resbuf)92 md5_read_ctx (const struct md5_ctx *ctx, void *resbuf)
93 {
94 ((md5_uint32 *) resbuf)[0] = SWAP (ctx->A);
95 ((md5_uint32 *) resbuf)[1] = SWAP (ctx->B);
96 ((md5_uint32 *) resbuf)[2] = SWAP (ctx->C);
97 ((md5_uint32 *) resbuf)[3] = SWAP (ctx->D);
98
99 return resbuf;
100 }
101
102 /* Process the remaining bytes in the internal buffer and the usual
103 prolog according to the standard and write the result to RESBUF.
104
105 IMPORTANT: On some systems it is required that RESBUF is correctly
106 aligned for a 32 bits value. */
107 void *
md5_finish_ctx(struct md5_ctx * ctx,void * resbuf)108 md5_finish_ctx (struct md5_ctx *ctx, void *resbuf)
109 {
110 /* Take yet unprocessed bytes into account. */
111 md5_uint32 bytes = ctx->buflen;
112 size_t pad;
113
114 /* Now count remaining bytes. */
115 ctx->total[0] += bytes;
116 if (ctx->total[0] < bytes)
117 ++ctx->total[1];
118
119 pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
120 memcpy (&ctx->buffer[bytes], fillbuf, pad);
121
122 /* Put the 64-bit file length in *bits* at the end of the buffer. */
123 *(md5_uint32 *) &ctx->buffer[bytes + pad] = SWAP (ctx->total[0] << 3);
124 *(md5_uint32 *) &ctx->buffer[bytes + pad + 4] = SWAP ((ctx->total[1] << 3) |
125 (ctx->total[0] >> 29));
126
127 /* Process last bytes. */
128 md5_process_block (ctx->buffer, bytes + pad + 8, ctx);
129
130 return md5_read_ctx (ctx, resbuf);
131 }
132
133 /* Compute MD5 message digest for bytes read from STREAM. The
134 resulting message digest number will be written into the 16 bytes
135 beginning at RESBLOCK. */
136 int
md5_stream(FILE * stream,void * resblock)137 md5_stream (FILE *stream, void *resblock)
138 {
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 while (1)
157 {
158 n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
159
160 sum += n;
161
162 if (sum == BLOCKSIZE)
163 break;
164
165 if (n == 0)
166 {
167 /* Check for the error flag IFF N == 0, so that we don't
168 exit the loop after a partial read due to e.g., EAGAIN
169 or EWOULDBLOCK. */
170 if (ferror (stream))
171 return 1;
172 goto process_partial_block;
173 }
174
175 /* We've read at least one byte, so ignore errors. But always
176 check for EOF, since feof may be true even though N > 0.
177 Otherwise, we could end up calling fread after EOF. */
178 if (feof (stream))
179 goto process_partial_block;
180 }
181
182 /* Process buffer with BLOCKSIZE bytes. Note that
183 BLOCKSIZE % 64 == 0
184 */
185 md5_process_block (buffer, BLOCKSIZE, &ctx);
186 }
187
188 process_partial_block:;
189
190 /* Process any remaining bytes. */
191 if (sum > 0)
192 md5_process_bytes (buffer, sum, &ctx);
193
194 /* Construct result in desired memory. */
195 md5_finish_ctx (&ctx, resblock);
196 return 0;
197 }
198
199 /* Compute MD5 message digest for LEN bytes beginning at BUFFER. The
200 result is always in little endian byte order, so that a byte-wise
201 output yields to the wanted ASCII representation of the message
202 digest. */
203 void *
md5_buffer(const char * buffer,size_t len,void * resblock)204 md5_buffer (const char *buffer, size_t len, void *resblock)
205 {
206 struct md5_ctx ctx;
207
208 /* Initialize the computation context. */
209 md5_init_ctx (&ctx);
210
211 /* Process whole buffer but last len % 64 bytes. */
212 md5_process_bytes (buffer, len, &ctx);
213
214 /* Put result in desired memory area. */
215 return md5_finish_ctx (&ctx, resblock);
216 }
217
218
219 void
md5_process_bytes(const void * buffer,size_t len,struct md5_ctx * ctx)220 md5_process_bytes (const void *buffer, size_t len, struct md5_ctx *ctx)
221 {
222 /* When we already have some bits in our internal buffer concatenate
223 both inputs first. */
224 if (ctx->buflen != 0)
225 {
226 size_t left_over = ctx->buflen;
227 size_t add = 128 - left_over > len ? len : 128 - left_over;
228
229 memcpy (&ctx->buffer[left_over], buffer, add);
230 ctx->buflen += add;
231
232 if (ctx->buflen > 64)
233 {
234 md5_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
235
236 ctx->buflen &= 63;
237 /* The regions in the following copy operation cannot overlap. */
238 memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
239 ctx->buflen);
240 }
241
242 buffer = (const char *) buffer + add;
243 len -= add;
244 }
245
246 /* Process available complete blocks. */
247 if (len >= 64)
248 {
249 #if !_STRING_ARCH_unaligned
250 # define alignof(type) offsetof (struct { char c; type x; }, x)
251 # define UNALIGNED_P(p) (((size_t) p) % alignof (md5_uint32) != 0)
252 if (UNALIGNED_P (buffer))
253 while (len > 64)
254 {
255 md5_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
256 buffer = (const char *) buffer + 64;
257 len -= 64;
258 }
259 else
260 #endif
261 {
262 md5_process_block (buffer, len & ~63, ctx);
263 buffer = (const char *) buffer + (len & ~63);
264 len &= 63;
265 }
266 }
267
268 /* Move remaining bytes in internal buffer. */
269 if (len > 0)
270 {
271 size_t left_over = ctx->buflen;
272
273 memcpy (&ctx->buffer[left_over], buffer, len);
274 left_over += len;
275 if (left_over >= 64)
276 {
277 md5_process_block (ctx->buffer, 64, ctx);
278 left_over -= 64;
279 memcpy (ctx->buffer, &ctx->buffer[64], left_over);
280 }
281 ctx->buflen = left_over;
282 }
283 }
284
285
286 /* These are the four functions used in the four steps of the MD5 algorithm
287 and defined in the RFC 1321. The first function is a little bit optimized
288 (as found in Colin Plumbs public domain implementation). */
289 /* #define FF(b, c, d) ((b & c) | (~b & d)) */
290 #define FF(b, c, d) (d ^ (b & (c ^ d)))
291 #define FG(b, c, d) FF (d, b, c)
292 #define FH(b, c, d) (b ^ c ^ d)
293 #define FI(b, c, d) (c ^ (b | ~d))
294
295 /* Process LEN bytes of BUFFER, accumulating context into CTX.
296 It is assumed that LEN % 64 == 0. */
297
298 void
md5_process_block(const void * buffer,size_t len,struct md5_ctx * ctx)299 md5_process_block (const void *buffer, size_t len, struct md5_ctx *ctx)
300 {
301 md5_uint32 correct_words[16];
302 const md5_uint32 *words = buffer;
303 size_t nwords = len / sizeof (md5_uint32);
304 const md5_uint32 *endp = words + nwords;
305 md5_uint32 A = ctx->A;
306 md5_uint32 B = ctx->B;
307 md5_uint32 C = ctx->C;
308 md5_uint32 D = ctx->D;
309
310 /* First increment the byte count. RFC 1321 specifies the possible
311 length of the file up to 2^64 bits. Here we only compute the
312 number of bytes. Do a double word increment. */
313 ctx->total[0] += len;
314 if (ctx->total[0] < len)
315 ++ctx->total[1];
316
317 /* Process all bytes in the buffer with 64 bytes in each round of
318 the loop. */
319 while (words < endp)
320 {
321 md5_uint32 *cwp = correct_words;
322 md5_uint32 A_save = A;
323 md5_uint32 B_save = B;
324 md5_uint32 C_save = C;
325 md5_uint32 D_save = D;
326
327 /* First round: using the given function, the context and a constant
328 the next context is computed. Because the algorithms processing
329 unit is a 32-bit word and it is determined to work on words in
330 little endian byte order we perhaps have to change the byte order
331 before the computation. To reduce the work for the next steps
332 we store the swapped words in the array CORRECT_WORDS. */
333
334 #define OP(a, b, c, d, s, T) \
335 do \
336 { \
337 a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T; \
338 ++words; \
339 CYCLIC (a, s); \
340 a += b; \
341 } \
342 while (0)
343
344 /* It is unfortunate that C does not provide an operator for
345 cyclic rotation. Hope the C compiler is smart enough. */
346 #define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s)))
347
348 /* Before we start, one word to the strange constants.
349 They are defined in RFC 1321 as
350
351 T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64
352
353 Here is an equivalent invocation using Perl:
354
355 perl -e 'foreach(1..64){printf "0x%08x\n", int (4294967296 * abs (sin $_))}'
356 */
357
358 /* Round 1. */
359 OP (A, B, C, D, 7, 0xd76aa478);
360 OP (D, A, B, C, 12, 0xe8c7b756);
361 OP (C, D, A, B, 17, 0x242070db);
362 OP (B, C, D, A, 22, 0xc1bdceee);
363 OP (A, B, C, D, 7, 0xf57c0faf);
364 OP (D, A, B, C, 12, 0x4787c62a);
365 OP (C, D, A, B, 17, 0xa8304613);
366 OP (B, C, D, A, 22, 0xfd469501);
367 OP (A, B, C, D, 7, 0x698098d8);
368 OP (D, A, B, C, 12, 0x8b44f7af);
369 OP (C, D, A, B, 17, 0xffff5bb1);
370 OP (B, C, D, A, 22, 0x895cd7be);
371 OP (A, B, C, D, 7, 0x6b901122);
372 OP (D, A, B, C, 12, 0xfd987193);
373 OP (C, D, A, B, 17, 0xa679438e);
374 OP (B, C, D, A, 22, 0x49b40821);
375
376 /* For the second to fourth round we have the possibly swapped words
377 in CORRECT_WORDS. Redefine the macro to take an additional first
378 argument specifying the function to use. */
379 #undef OP
380 #define OP(f, a, b, c, d, k, s, T) \
381 do \
382 { \
383 a += f (b, c, d) + correct_words[k] + T; \
384 CYCLIC (a, s); \
385 a += b; \
386 } \
387 while (0)
388
389 /* Round 2. */
390 OP (FG, A, B, C, D, 1, 5, 0xf61e2562);
391 OP (FG, D, A, B, C, 6, 9, 0xc040b340);
392 OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
393 OP (FG, B, C, D, A, 0, 20, 0xe9b6c7aa);
394 OP (FG, A, B, C, D, 5, 5, 0xd62f105d);
395 OP (FG, D, A, B, C, 10, 9, 0x02441453);
396 OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
397 OP (FG, B, C, D, A, 4, 20, 0xe7d3fbc8);
398 OP (FG, A, B, C, D, 9, 5, 0x21e1cde6);
399 OP (FG, D, A, B, C, 14, 9, 0xc33707d6);
400 OP (FG, C, D, A, B, 3, 14, 0xf4d50d87);
401 OP (FG, B, C, D, A, 8, 20, 0x455a14ed);
402 OP (FG, A, B, C, D, 13, 5, 0xa9e3e905);
403 OP (FG, D, A, B, C, 2, 9, 0xfcefa3f8);
404 OP (FG, C, D, A, B, 7, 14, 0x676f02d9);
405 OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);
406
407 /* Round 3. */
408 OP (FH, A, B, C, D, 5, 4, 0xfffa3942);
409 OP (FH, D, A, B, C, 8, 11, 0x8771f681);
410 OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
411 OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
412 OP (FH, A, B, C, D, 1, 4, 0xa4beea44);
413 OP (FH, D, A, B, C, 4, 11, 0x4bdecfa9);
414 OP (FH, C, D, A, B, 7, 16, 0xf6bb4b60);
415 OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
416 OP (FH, A, B, C, D, 13, 4, 0x289b7ec6);
417 OP (FH, D, A, B, C, 0, 11, 0xeaa127fa);
418 OP (FH, C, D, A, B, 3, 16, 0xd4ef3085);
419 OP (FH, B, C, D, A, 6, 23, 0x04881d05);
420 OP (FH, A, B, C, D, 9, 4, 0xd9d4d039);
421 OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
422 OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
423 OP (FH, B, C, D, A, 2, 23, 0xc4ac5665);
424
425 /* Round 4. */
426 OP (FI, A, B, C, D, 0, 6, 0xf4292244);
427 OP (FI, D, A, B, C, 7, 10, 0x432aff97);
428 OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
429 OP (FI, B, C, D, A, 5, 21, 0xfc93a039);
430 OP (FI, A, B, C, D, 12, 6, 0x655b59c3);
431 OP (FI, D, A, B, C, 3, 10, 0x8f0ccc92);
432 OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
433 OP (FI, B, C, D, A, 1, 21, 0x85845dd1);
434 OP (FI, A, B, C, D, 8, 6, 0x6fa87e4f);
435 OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
436 OP (FI, C, D, A, B, 6, 15, 0xa3014314);
437 OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
438 OP (FI, A, B, C, D, 4, 6, 0xf7537e82);
439 OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
440 OP (FI, C, D, A, B, 2, 15, 0x2ad7d2bb);
441 OP (FI, B, C, D, A, 9, 21, 0xeb86d391);
442
443 /* Add the starting values of the context. */
444 A += A_save;
445 B += B_save;
446 C += C_save;
447 D += D_save;
448 }
449
450 /* Put checksum in context given as argument. */
451 ctx->A = A;
452 ctx->B = B;
453 ctx->C = C;
454 ctx->D = D;
455 }
456