1  /*
  2   * written by Colin Plumb in 1993, no copyright is claimed.
  3   * This code is in the public domain; do with it what you wish.
  4   *
  5   * Equivalent code is available from RSA Data Security, Inc.
  6   * This code has been tested against that, and is equivalent,
  7   * except that you don't need to include two pages of legalese
  8   * with every copy.
  9   *
 10   * To compute the message digest of a chunk of bytes, declare an
 11   * MD5Context structure, pass it to MD5Init, call MD5Update as
 12   * needed on buffers full of bytes, and then call MD5Final, which
 13   * will fill a supplied 16-byte array with the digest.
 14   */
 15  
 16  #ifdef HAVE_CONFIG_H
 17  #include <config.h>  // Must come first
 18  #endif
 19  
 20  #include <string.h>
 21  
 22  #include "common/md5.h"
 23  
 24  namespace google_breakpad {
 25  
 26  #ifndef WORDS_BIGENDIAN
 27  #define byteReverse(buf, len)   /* Nothing */
 28  #else
 29  /*
 30   * Note: this code is harmless on little-endian machines.
 31   */
 32  static void byteReverse(unsigned char *buf, unsigned longs)
 33  {
 34    u32 t;
 35    do {
 36      t = (u32) ((unsigned) buf[3] << 8 | buf[2]) << 16 |
 37        ((unsigned) buf[1] << 8 | buf[0]);
 38      *(u32*) buf = t;
 39      buf += 4;
 40    } while (--longs);
 41  }
 42  #endif
 43  
 44  static void MD5Transform(u32 buf[4], u32 const in[16]);
 45  
 46  /*
 47   * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
 48   * initialization constants.
 49   */
 50  void MD5Init(struct MD5Context *ctx)
 51  {
 52    ctx->buf[0] = 0x67452301;
 53    ctx->buf[1] = 0xefcdab89;
 54    ctx->buf[2] = 0x98badcfe;
 55    ctx->buf[3] = 0x10325476;
 56  
 57    ctx->bits[0] = 0;
 58    ctx->bits[1] = 0;
 59  }
 60  
 61  /*
 62   * Update context to reflect the concatenation of another buffer full
 63   * of bytes.
 64   */
 65  void MD5Update(struct MD5Context *ctx, unsigned char const *buf, size_t len)
 66  {
 67    u32 t;
 68  
 69    /* Update bitcount */
 70  
 71    t = ctx->bits[0];
 72    if ((ctx->bits[0] = t + ((u32) len << 3)) < t)
 73      ctx->bits[1]++;         /* Carry from low to high */
 74    ctx->bits[1] += len >> 29;
 75  
 76    t = (t >> 3) & 0x3f;        /* Bytes already in shsInfo->data */
 77  
 78    /* Handle any leading odd-sized chunks */
 79  
 80    if (t) {
 81      unsigned char *p = (unsigned char*) ctx->in + t;
 82  
 83      t = 64 - t;
 84      if (len < t) {
 85        memcpy(p, buf, len);
 86        return;
 87      }
 88      memcpy(p, buf, t);
 89      byteReverse(ctx->in, 16);
 90      MD5Transform(ctx->buf, (u32*) ctx->in);
 91      buf += t;
 92      len -= t;
 93    }
 94    /* Process data in 64-byte chunks */
 95  
 96    while (len >= 64) {
 97      memcpy(ctx->in, buf, 64);
 98      byteReverse(ctx->in, 16);
 99      MD5Transform(ctx->buf, (u32*) ctx->in);
100      buf += 64;
101      len -= 64;
102    }
103  
104    /* Handle any remaining bytes of data. */
105  
106    memcpy(ctx->in, buf, len);
107  }
108  
109  /*
110   * Final wrapup - pad to 64-byte boundary with the bit pattern
111   * 1 0* (64-bit count of bits processed, MSB-first)
112   */
113  void MD5Final(unsigned char digest[16], struct MD5Context *ctx)
114  {
115    unsigned count;
116    unsigned char *p;
117  
118    /* Compute number of bytes mod 64 */
119    count = (ctx->bits[0] >> 3) & 0x3F;
120  
121    /* Set the first char of padding to 0x80.  This is safe since there is
122       always at least one byte free */
123    p = ctx->in + count;
124    *p++ = 0x80;
125  
126    /* Bytes of padding needed to make 64 bytes */
127    count = 64 - 1 - count;
128  
129    /* Pad out to 56 mod 64 */
130    if (count < 8) {
131      /* Two lots of padding:  Pad the first block to 64 bytes */
132      memset(p, 0, count);
133      byteReverse(ctx->in, 16);
134      MD5Transform(ctx->buf, (u32*) ctx->in);
135  
136      /* Now fill the next block with 56 bytes */
137      memset(ctx->in, 0, 56);
138    } else {
139      /* Pad block to 56 bytes */
140      memset(p, 0, count - 8);
141    }
142    byteReverse(ctx->in, 14);
143  
144    /* Append length in bits and transform */
145    memcpy(&ctx->in[14], &ctx->bits[0], sizeof(u32));
146    memcpy(&ctx->in[15], &ctx->bits[1], sizeof(u32));
147  
148    MD5Transform(ctx->buf, (u32*) ctx->in);
149    byteReverse((unsigned char*) ctx->buf, 4);
150    memcpy(digest, ctx->buf, 16);
151    memset(ctx, 0, sizeof(*ctx));        /* In case it's sensitive */
152  }
153  
154  /* The four core functions - F1 is optimized somewhat */
155  
156  /* #define F1(x, y, z) (x & y | ~x & z) */
157  #define F1(x, y, z) (z ^ (x & (y ^ z)))
158  #define F2(x, y, z) F1(z, x, y)
159  #define F3(x, y, z) (x ^ y ^ z)
160  #define F4(x, y, z) (y ^ (x | ~z))
161  
162  /* This is the central step in the MD5 algorithm. */
163  #define MD5STEP(f, w, x, y, z, data, s) \
164    ( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )
165  
166  /*
167   * The core of the MD5 algorithm, this alters an existing MD5 hash to
168   * reflect the addition of 16 longwords of new data.  MD5Update blocks
169   * the data and converts bytes into longwords for this routine.
170   */
171  static void MD5Transform(u32 buf[4], u32 const in[16])
172  {
173    u32 a, b, c, d;
174  
175    a = buf[0];
176    b = buf[1];
177    c = buf[2];
178    d = buf[3];
179  
180    MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
181    MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
182    MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
183    MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
184    MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
185    MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
186    MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
187    MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
188    MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
189    MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
190    MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
191    MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
192    MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
193    MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
194    MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
195    MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);
196  
197    MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
198    MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
199    MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
200    MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
201    MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
202    MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
203    MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
204    MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
205    MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
206    MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
207    MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
208    MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
209    MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
210    MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
211    MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
212    MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);
213  
214    MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
215    MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
216    MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
217    MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
218    MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
219    MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
220    MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
221    MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
222    MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
223    MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
224    MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
225    MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
226    MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
227    MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
228    MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
229    MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);
230  
231    MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
232    MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
233    MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
234    MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
235    MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
236    MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
237    MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
238    MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
239    MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
240    MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
241    MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
242    MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
243    MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
244    MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
245    MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
246    MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);
247  
248    buf[0] += a;
249    buf[1] += b;
250    buf[2] += c;
251    buf[3] += d;
252  }
253  
254  }  // namespace google_breakpad
255