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) 1995-2011, 2015 Red Hat, Inc.
4    This file is part of elfutils.
5    Written by Ulrich Drepper <drepper@redhat.com>, 1995.
6 
7    This file is free software; you can redistribute it and/or modify
8    it under the terms of either
9 
10      * the GNU Lesser General Public License as published by the Free
11        Software Foundation; either version 3 of the License, or (at
12        your option) any later version
13 
14    or
15 
16      * the GNU General Public License as published by the Free
17        Software Foundation; either version 2 of the License, or (at
18        your option) any later version
19 
20    or both in parallel, as here.
21 
22    elfutils is distributed in the hope that it will be useful, but
23    WITHOUT ANY WARRANTY; without even the implied warranty of
24    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
25    General Public License for more details.
26 
27    You should have received copies of the GNU General Public License and
28    the GNU Lesser General Public License along with this program.  If
29    not, see <http://www.gnu.org/licenses/>.  */
30 
31 #ifdef HAVE_CONFIG_H
32 # include <config.h>
33 #endif
34 
35 #include <stdlib.h>
36 #include <string.h>
37 #include <sys/types.h>
38 
39 #include "md5.h"
40 #include "system.h"
41 
42 #define SWAP(n) LE32 (n)
43 
44 /* This array contains the bytes used to pad the buffer to the next
45    64-byte boundary.  (RFC 1321, 3.1: Step 1)  */
46 static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */ };
47 
48 
49 /* Initialize structure containing state of computation.
50    (RFC 1321, 3.3: Step 3)  */
51 void
md5_init_ctx(struct md5_ctx * ctx)52 md5_init_ctx (struct md5_ctx *ctx)
53 {
54   ctx->A = 0x67452301;
55   ctx->B = 0xefcdab89;
56   ctx->C = 0x98badcfe;
57   ctx->D = 0x10325476;
58 
59   ctx->total[0] = ctx->total[1] = 0;
60   ctx->buflen = 0;
61 }
62 
63 /* Put result from CTX in first 16 bytes following RESBUF.  The result
64    must be in little endian byte order.
65 
66    IMPORTANT: On some systems it is required that RESBUF is correctly
67    aligned for a 32 bits value.  */
68 void *
md5_read_ctx(const struct md5_ctx * ctx,void * resbuf)69 md5_read_ctx (const struct md5_ctx *ctx, void *resbuf)
70 {
71   ((md5_uint32 *) resbuf)[0] = SWAP (ctx->A);
72   ((md5_uint32 *) resbuf)[1] = SWAP (ctx->B);
73   ((md5_uint32 *) resbuf)[2] = SWAP (ctx->C);
74   ((md5_uint32 *) resbuf)[3] = SWAP (ctx->D);
75 
76   return resbuf;
77 }
78 
79 static void
le64_copy(char * dest,uint64_t x)80 le64_copy (char *dest, uint64_t x)
81 {
82   for (size_t i = 0; i < 8; ++i)
83     {
84       dest[i] = (uint8_t) x;
85       x >>= 8;
86     }
87 }
88 
89 /* Process the remaining bytes in the internal buffer and the usual
90    prolog according to the standard and write the result to RESBUF.
91 
92    IMPORTANT: On some systems it is required that RESBUF is correctly
93    aligned for a 32 bits value.  */
94 void *
md5_finish_ctx(struct md5_ctx * ctx,void * resbuf)95 md5_finish_ctx (struct md5_ctx *ctx, void *resbuf)
96 {
97   /* Take yet unprocessed bytes into account.  */
98   md5_uint32 bytes = ctx->buflen;
99   size_t pad;
100 
101   /* Now count remaining bytes.  */
102   ctx->total[0] += bytes;
103   if (ctx->total[0] < bytes)
104     ++ctx->total[1];
105 
106   pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
107   memcpy (&ctx->buffer[bytes], fillbuf, pad);
108 
109   /* Put the 64-bit file length in *bits* at the end of the buffer.  */
110   const uint64_t bit_length = ((ctx->total[0] << 3)
111 			       + ((uint64_t) ((ctx->total[1] << 3) |
112 					      (ctx->total[0] >> 29)) << 32));
113   le64_copy (&ctx->buffer[bytes + pad], bit_length);
114 
115   /* Process last bytes.  */
116   md5_process_block (ctx->buffer, bytes + pad + 8, ctx);
117 
118   return md5_read_ctx (ctx, resbuf);
119 }
120 
121 
122 #ifdef NEED_MD5_STREAM
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
md5_stream(FILE * stream,void * resblock)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 #endif
177 
178 
179 #ifdef NEED_MD5_BUFFER
180 /* Compute MD5 message digest for LEN bytes beginning at BUFFER.  The
181    result is always in little endian byte order, so that a byte-wise
182    output yields to the wanted ASCII representation of the message
183    digest.  */
184 void *
md5_buffer(const char * buffer,size_t len,void * resblock)185 md5_buffer (const char *buffer, size_t len, void *resblock)
186 {
187   struct md5_ctx ctx;
188 
189   /* Initialize the computation context.  */
190   md5_init_ctx (&ctx);
191 
192   /* Process whole buffer but last len % 64 bytes.  */
193   md5_process_bytes (buffer, len, &ctx);
194 
195   /* Put result in desired memory area.  */
196   return md5_finish_ctx (&ctx, resblock);
197 }
198 #endif
199 
200 
201 void
md5_process_bytes(const void * buffer,size_t len,struct md5_ctx * ctx)202 md5_process_bytes (const void *buffer, size_t len, struct md5_ctx *ctx)
203 {
204   /* When we already have some bits in our internal buffer concatenate
205      both inputs first.  */
206   if (ctx->buflen != 0)
207     {
208       size_t left_over = ctx->buflen;
209       size_t add = 128 - left_over > len ? len : 128 - left_over;
210 
211       memcpy (&ctx->buffer[left_over], buffer, add);
212       ctx->buflen += add;
213 
214       if (ctx->buflen > 64)
215 	{
216 	  md5_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
217 
218 	  ctx->buflen &= 63;
219 	  /* The regions in the following copy operation cannot overlap.  */
220 	  memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
221 		  ctx->buflen);
222 	}
223 
224       buffer = (const char *) buffer + add;
225       len -= add;
226     }
227 
228   /* Process available complete blocks.  */
229   if (len >= 64)
230     {
231 #if !_STRING_ARCH_unaligned
232 /* To check alignment gcc has an appropriate operator.  Other
233    compilers don't.  */
234 # if __GNUC__ >= 2
235 #  define UNALIGNED_P(p) (((md5_uintptr) p) % __alignof__ (md5_uint32) != 0)
236 # else
237 #  define UNALIGNED_P(p) (((md5_uintptr) p) % sizeof (md5_uint32) != 0)
238 # endif
239       if (UNALIGNED_P (buffer))
240 	while (len > 64)
241 	  {
242 	    md5_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
243 	    buffer = (const char *) buffer + 64;
244 	    len -= 64;
245 	  }
246       else
247 #endif
248 	{
249 	  md5_process_block (buffer, len & ~63, ctx);
250 	  buffer = (const char *) buffer + (len & ~63);
251 	  len &= 63;
252 	}
253     }
254 
255   /* Move remaining bytes in internal buffer.  */
256   if (len > 0)
257     {
258       size_t left_over = ctx->buflen;
259 
260       memcpy (&ctx->buffer[left_over], buffer, len);
261       left_over += len;
262       if (left_over >= 64)
263 	{
264 	  md5_process_block (ctx->buffer, 64, ctx);
265 	  left_over -= 64;
266 	  memcpy (ctx->buffer, &ctx->buffer[64], left_over);
267 	}
268       ctx->buflen = left_over;
269     }
270 }
271 
272 
273 /* These are the four functions used in the four steps of the MD5 algorithm
274    and defined in the RFC 1321.  The first function is a little bit optimized
275    (as found in Colin Plumbs public domain implementation).  */
276 /* #define FF(b, c, d) ((b & c) | (~b & d)) */
277 #define FF(b, c, d) (d ^ (b & (c ^ d)))
278 #define FG(b, c, d) FF (d, b, c)
279 #define FH(b, c, d) (b ^ c ^ d)
280 #define FI(b, c, d) (c ^ (b | ~d))
281 
282 /* Process LEN bytes of BUFFER, accumulating context into CTX.
283    It is assumed that LEN % 64 == 0.  */
284 
285 void
md5_process_block(const void * buffer,size_t len,struct md5_ctx * ctx)286 md5_process_block (const void *buffer, size_t len, struct md5_ctx *ctx)
287 {
288   md5_uint32 correct_words[16];
289   const md5_uint32 *words = buffer;
290   size_t nwords = len / sizeof (md5_uint32);
291   const md5_uint32 *endp = words + nwords;
292   md5_uint32 A = ctx->A;
293   md5_uint32 B = ctx->B;
294   md5_uint32 C = ctx->C;
295   md5_uint32 D = ctx->D;
296 
297   /* First increment the byte count.  RFC 1321 specifies the possible
298      length of the file up to 2^64 bits.  Here we only compute the
299      number of bytes.  Do a double word increment.  */
300   ctx->total[0] += len;
301   if (ctx->total[0] < len)
302     ++ctx->total[1];
303 
304   /* Process all bytes in the buffer with 64 bytes in each round of
305      the loop.  */
306   while (words < endp)
307     {
308       md5_uint32 *cwp = correct_words;
309       md5_uint32 A_save = A;
310       md5_uint32 B_save = B;
311       md5_uint32 C_save = C;
312       md5_uint32 D_save = D;
313 
314       /* First round: using the given function, the context and a constant
315 	 the next context is computed.  Because the algorithms processing
316 	 unit is a 32-bit word and it is determined to work on words in
317 	 little endian byte order we perhaps have to change the byte order
318 	 before the computation.  To reduce the work for the next steps
319 	 we store the swapped words in the array CORRECT_WORDS.  */
320 
321 #define OP(a, b, c, d, s, T)						\
322       do								\
323         {								\
324 	  a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T;		\
325 	  ++words;							\
326 	  CYCLIC (a, s);						\
327 	  a += b;							\
328         }								\
329       while (0)
330 
331       /* It is unfortunate that C does not provide an operator for
332 	 cyclic rotation.  Hope the C compiler is smart enough.  */
333 #define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s)))
334 
335       /* Before we start, one word to the strange constants.
336 	 They are defined in RFC 1321 as
337 
338 	 T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64
339        */
340 
341       /* Round 1.  */
342       OP (A, B, C, D,  7, 0xd76aa478);
343       OP (D, A, B, C, 12, 0xe8c7b756);
344       OP (C, D, A, B, 17, 0x242070db);
345       OP (B, C, D, A, 22, 0xc1bdceee);
346       OP (A, B, C, D,  7, 0xf57c0faf);
347       OP (D, A, B, C, 12, 0x4787c62a);
348       OP (C, D, A, B, 17, 0xa8304613);
349       OP (B, C, D, A, 22, 0xfd469501);
350       OP (A, B, C, D,  7, 0x698098d8);
351       OP (D, A, B, C, 12, 0x8b44f7af);
352       OP (C, D, A, B, 17, 0xffff5bb1);
353       OP (B, C, D, A, 22, 0x895cd7be);
354       OP (A, B, C, D,  7, 0x6b901122);
355       OP (D, A, B, C, 12, 0xfd987193);
356       OP (C, D, A, B, 17, 0xa679438e);
357       OP (B, C, D, A, 22, 0x49b40821);
358 
359       /* For the second to fourth round we have the possibly swapped words
360 	 in CORRECT_WORDS.  Redefine the macro to take an additional first
361 	 argument specifying the function to use.  */
362 #undef OP
363 #define OP(f, a, b, c, d, k, s, T)					\
364       do 								\
365 	{								\
366 	  a += f (b, c, d) + correct_words[k] + T;			\
367 	  CYCLIC (a, s);						\
368 	  a += b;							\
369 	}								\
370       while (0)
371 
372       /* Round 2.  */
373       OP (FG, A, B, C, D,  1,  5, 0xf61e2562);
374       OP (FG, D, A, B, C,  6,  9, 0xc040b340);
375       OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
376       OP (FG, B, C, D, A,  0, 20, 0xe9b6c7aa);
377       OP (FG, A, B, C, D,  5,  5, 0xd62f105d);
378       OP (FG, D, A, B, C, 10,  9, 0x02441453);
379       OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
380       OP (FG, B, C, D, A,  4, 20, 0xe7d3fbc8);
381       OP (FG, A, B, C, D,  9,  5, 0x21e1cde6);
382       OP (FG, D, A, B, C, 14,  9, 0xc33707d6);
383       OP (FG, C, D, A, B,  3, 14, 0xf4d50d87);
384       OP (FG, B, C, D, A,  8, 20, 0x455a14ed);
385       OP (FG, A, B, C, D, 13,  5, 0xa9e3e905);
386       OP (FG, D, A, B, C,  2,  9, 0xfcefa3f8);
387       OP (FG, C, D, A, B,  7, 14, 0x676f02d9);
388       OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);
389 
390       /* Round 3.  */
391       OP (FH, A, B, C, D,  5,  4, 0xfffa3942);
392       OP (FH, D, A, B, C,  8, 11, 0x8771f681);
393       OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
394       OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
395       OP (FH, A, B, C, D,  1,  4, 0xa4beea44);
396       OP (FH, D, A, B, C,  4, 11, 0x4bdecfa9);
397       OP (FH, C, D, A, B,  7, 16, 0xf6bb4b60);
398       OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
399       OP (FH, A, B, C, D, 13,  4, 0x289b7ec6);
400       OP (FH, D, A, B, C,  0, 11, 0xeaa127fa);
401       OP (FH, C, D, A, B,  3, 16, 0xd4ef3085);
402       OP (FH, B, C, D, A,  6, 23, 0x04881d05);
403       OP (FH, A, B, C, D,  9,  4, 0xd9d4d039);
404       OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
405       OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
406       OP (FH, B, C, D, A,  2, 23, 0xc4ac5665);
407 
408       /* Round 4.  */
409       OP (FI, A, B, C, D,  0,  6, 0xf4292244);
410       OP (FI, D, A, B, C,  7, 10, 0x432aff97);
411       OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
412       OP (FI, B, C, D, A,  5, 21, 0xfc93a039);
413       OP (FI, A, B, C, D, 12,  6, 0x655b59c3);
414       OP (FI, D, A, B, C,  3, 10, 0x8f0ccc92);
415       OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
416       OP (FI, B, C, D, A,  1, 21, 0x85845dd1);
417       OP (FI, A, B, C, D,  8,  6, 0x6fa87e4f);
418       OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
419       OP (FI, C, D, A, B,  6, 15, 0xa3014314);
420       OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
421       OP (FI, A, B, C, D,  4,  6, 0xf7537e82);
422       OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
423       OP (FI, C, D, A, B,  2, 15, 0x2ad7d2bb);
424       OP (FI, B, C, D, A,  9, 21, 0xeb86d391);
425 
426       /* Add the starting values of the context.  */
427       A += A_save;
428       B += B_save;
429       C += C_save;
430       D += D_save;
431     }
432 
433   /* Put checksum in context given as argument.  */
434   ctx->A = A;
435   ctx->B = B;
436   ctx->C = C;
437   ctx->D = D;
438 }
439