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  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
  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
  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. }
  441.