1/*
2 * This code implements the MD5 message-digest algorithm.
3 * The algorithm is due to Ron Rivest.  This code was
4 * written by Colin Plumb in 1993, no copyright is claimed.
5 * This code is in the public domain; do with it what you wish.
6 *
7 * Equivalent code is available from RSA Data Security, Inc.
8 * This code has been tested against that, and is equivalent,
9 * except that you don't need to include two pages of legalese
10 * with every copy.
11 *
12 * To compute the message digest of a chunk of bytes, declare an
13 * MD5Context structure, pass it to MD5Init, call MD5Update as
14 * needed on buffers full of bytes, and then call MD5Final, which
15 * will fill a supplied 16-byte array with the digest.
16 */
17
18// Changes from original C code:
19// Ported to C++, type casting, Google code style.
20
21#include "talk/base/md5.h"
22
23// TODO: Avoid memcmpy - hash directly from memory.
24#include <string.h>  // for memcpy().
25
26#include "talk/base/byteorder.h"  // for ARCH_CPU_LITTLE_ENDIAN.
27
28#ifdef ARCH_CPU_LITTLE_ENDIAN
29#define ByteReverse(buf, len)  // Nothing.
30#else  // ARCH_CPU_BIG_ENDIAN
31static void ByteReverse(uint32* buf, int len) {
32  for (int i = 0; i < len; ++i) {
33    buf[i] = talk_base::GetLE32(&buf[i]);
34  }
35}
36#endif
37
38// Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
39// initialization constants.
40void MD5Init(MD5Context* ctx) {
41  ctx->buf[0] = 0x67452301;
42  ctx->buf[1] = 0xefcdab89;
43  ctx->buf[2] = 0x98badcfe;
44  ctx->buf[3] = 0x10325476;
45  ctx->bits[0] = 0;
46  ctx->bits[1] = 0;
47}
48
49// Update context to reflect the concatenation of another buffer full of bytes.
50void MD5Update(MD5Context* ctx, const uint8* buf, size_t len) {
51  // Update bitcount.
52  uint32 t = ctx->bits[0];
53  if ((ctx->bits[0] = t + (static_cast<uint32>(len) << 3)) < t) {
54    ctx->bits[1]++;  // Carry from low to high.
55  }
56  ctx->bits[1] += static_cast<uint32>(len >> 29);
57  t = (t >> 3) & 0x3f;  // Bytes already in shsInfo->data.
58
59  // Handle any leading odd-sized chunks.
60  if (t) {
61    uint8* p = reinterpret_cast<uint8*>(ctx->in) + t;
62
63    t = 64-t;
64    if (len < t) {
65      memcpy(p, buf, len);
66      return;
67    }
68    memcpy(p, buf, t);
69    ByteReverse(ctx->in, 16);
70    MD5Transform(ctx->buf, ctx->in);
71    buf += t;
72    len -= t;
73  }
74
75  // Process data in 64-byte chunks.
76  while (len >= 64) {
77    memcpy(ctx->in, buf, 64);
78    ByteReverse(ctx->in, 16);
79    MD5Transform(ctx->buf, ctx->in);
80    buf += 64;
81    len -= 64;
82  }
83
84  // Handle any remaining bytes of data.
85  memcpy(ctx->in, buf, len);
86}
87
88// Final wrapup - pad to 64-byte boundary with the bit pattern.
89// 1 0* (64-bit count of bits processed, MSB-first)
90void MD5Final(MD5Context* ctx, uint8 digest[16]) {
91  // Compute number of bytes mod 64.
92  uint32 count = (ctx->bits[0] >> 3) & 0x3F;
93
94  // Set the first char of padding to 0x80.  This is safe since there is
95  // always at least one byte free.
96  uint8* p = reinterpret_cast<uint8*>(ctx->in) + count;
97  *p++ = 0x80;
98
99  // Bytes of padding needed to make 64 bytes.
100  count = 64 - 1 - count;
101
102  // Pad out to 56 mod 64.
103  if (count < 8) {
104    // Two lots of padding:  Pad the first block to 64 bytes.
105    memset(p, 0, count);
106    ByteReverse(ctx->in, 16);
107    MD5Transform(ctx->buf, ctx->in);
108
109    // Now fill the next block with 56 bytes.
110    memset(ctx->in, 0, 56);
111  } else {
112    // Pad block to 56 bytes.
113    memset(p, 0, count - 8);
114  }
115  ByteReverse(ctx->in, 14);
116
117  // Append length in bits and transform.
118  ctx->in[14] = ctx->bits[0];
119  ctx->in[15] = ctx->bits[1];
120
121  MD5Transform(ctx->buf, ctx->in);
122  ByteReverse(ctx->buf, 4);
123  memcpy(digest, ctx->buf, 16);
124  memset(ctx, 0, sizeof(*ctx));  // In case it's sensitive.
125}
126
127// The four core functions - F1 is optimized somewhat.
128// #define F1(x, y, z) (x & y | ~x & z)
129#define F1(x, y, z) (z ^ (x & (y ^ z)))
130#define F2(x, y, z) F1(z, x, y)
131#define F3(x, y, z) (x ^ y ^ z)
132#define F4(x, y, z) (y ^ (x | ~z))
133
134// This is the central step in the MD5 algorithm.
135#define MD5STEP(f, w, x, y, z, data, s) \
136    (w += f(x, y, z) + data, w = w << s | w >> (32 - s), w += x)
137
138// The core of the MD5 algorithm, this alters an existing MD5 hash to
139// reflect the addition of 16 longwords of new data.  MD5Update blocks
140// the data and converts bytes into longwords for this routine.
141void MD5Transform(uint32 buf[4], const uint32 in[16]) {
142  uint32 a = buf[0];
143  uint32 b = buf[1];
144  uint32 c = buf[2];
145  uint32 d = buf[3];
146
147  MD5STEP(F1, a, b, c, d, in[ 0] + 0xd76aa478, 7);
148  MD5STEP(F1, d, a, b, c, in[ 1] + 0xe8c7b756, 12);
149  MD5STEP(F1, c, d, a, b, in[ 2] + 0x242070db, 17);
150  MD5STEP(F1, b, c, d, a, in[ 3] + 0xc1bdceee, 22);
151  MD5STEP(F1, a, b, c, d, in[ 4] + 0xf57c0faf, 7);
152  MD5STEP(F1, d, a, b, c, in[ 5] + 0x4787c62a, 12);
153  MD5STEP(F1, c, d, a, b, in[ 6] + 0xa8304613, 17);
154  MD5STEP(F1, b, c, d, a, in[ 7] + 0xfd469501, 22);
155  MD5STEP(F1, a, b, c, d, in[ 8] + 0x698098d8, 7);
156  MD5STEP(F1, d, a, b, c, in[ 9] + 0x8b44f7af, 12);
157  MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
158  MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
159  MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
160  MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
161  MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
162  MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);
163
164  MD5STEP(F2, a, b, c, d, in[ 1] + 0xf61e2562, 5);
165  MD5STEP(F2, d, a, b, c, in[ 6] + 0xc040b340, 9);
166  MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
167  MD5STEP(F2, b, c, d, a, in[ 0] + 0xe9b6c7aa, 20);
168  MD5STEP(F2, a, b, c, d, in[ 5] + 0xd62f105d, 5);
169  MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
170  MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
171  MD5STEP(F2, b, c, d, a, in[ 4] + 0xe7d3fbc8, 20);
172  MD5STEP(F2, a, b, c, d, in[ 9] + 0x21e1cde6, 5);
173  MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
174  MD5STEP(F2, c, d, a, b, in[ 3] + 0xf4d50d87, 14);
175  MD5STEP(F2, b, c, d, a, in[ 8] + 0x455a14ed, 20);
176  MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
177  MD5STEP(F2, d, a, b, c, in[ 2] + 0xfcefa3f8, 9);
178  MD5STEP(F2, c, d, a, b, in[ 7] + 0x676f02d9, 14);
179  MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);
180
181  MD5STEP(F3, a, b, c, d, in[ 5] + 0xfffa3942, 4);
182  MD5STEP(F3, d, a, b, c, in[ 8] + 0x8771f681, 11);
183  MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
184  MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
185  MD5STEP(F3, a, b, c, d, in[ 1] + 0xa4beea44, 4);
186  MD5STEP(F3, d, a, b, c, in[ 4] + 0x4bdecfa9, 11);
187  MD5STEP(F3, c, d, a, b, in[ 7] + 0xf6bb4b60, 16);
188  MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
189  MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
190  MD5STEP(F3, d, a, b, c, in[ 0] + 0xeaa127fa, 11);
191  MD5STEP(F3, c, d, a, b, in[ 3] + 0xd4ef3085, 16);
192  MD5STEP(F3, b, c, d, a, in[ 6] + 0x04881d05, 23);
193  MD5STEP(F3, a, b, c, d, in[ 9] + 0xd9d4d039, 4);
194  MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
195  MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
196  MD5STEP(F3, b, c, d, a, in[ 2] + 0xc4ac5665, 23);
197
198  MD5STEP(F4, a, b, c, d, in[ 0] + 0xf4292244, 6);
199  MD5STEP(F4, d, a, b, c, in[ 7] + 0x432aff97, 10);
200  MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
201  MD5STEP(F4, b, c, d, a, in[ 5] + 0xfc93a039, 21);
202  MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
203  MD5STEP(F4, d, a, b, c, in[ 3] + 0x8f0ccc92, 10);
204  MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
205  MD5STEP(F4, b, c, d, a, in[ 1] + 0x85845dd1, 21);
206  MD5STEP(F4, a, b, c, d, in[ 8] + 0x6fa87e4f, 6);
207  MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
208  MD5STEP(F4, c, d, a, b, in[ 6] + 0xa3014314, 15);
209  MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
210  MD5STEP(F4, a, b, c, d, in[ 4] + 0xf7537e82, 6);
211  MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
212  MD5STEP(F4, c, d, a, b, in[ 2] + 0x2ad7d2bb, 15);
213  MD5STEP(F4, b, c, d, a, in[ 9] + 0xeb86d391, 21);
214  buf[0] += a;
215  buf[1] += b;
216  buf[2] += c;
217  buf[3] += d;
218}
219