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, 2011 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
md5_init_ctx(struct md5_ctx * ctx)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 *
md5_read_ctx(const struct md5_ctx * ctx,void * resbuf)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 *
md5_finish_ctx(struct md5_ctx * ctx,void * resbuf)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
md5_stream(FILE * stream,void * resblock)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 *
md5_buffer(const char * buffer,size_t len,void * resblock)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
md5_process_bytes(const void * buffer,size_t len,struct md5_ctx * ctx)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
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
md5_process_block(const void * buffer,size_t len,struct md5_ctx * ctx)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 }
441