1/*
2 * Copyright 2012 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 *
7 * The following code is based on the description in RFC 1321.
8 * http://www.ietf.org/rfc/rfc1321.txt
9 */
10
11//The following macros can be defined to affect the MD5 code generated.
12//SK_MD5_CLEAR_DATA causes all intermediate state to be overwritten with 0's.
13//SK_CPU_LENDIAN allows 32 bit <=> 8 bit conversions without copies (if alligned).
14//SK_CPU_FAST_UNALIGNED_ACCESS allows 32 bit <=> 8 bit conversions without copies if SK_CPU_LENDIAN.
15
16#include "src/core/SkMD5.h"
17#include <string.h>
18
19/** MD5 basic transformation. Transforms state based on block. */
20static void transform(uint32_t state[4], const uint8_t block[64]);
21
22/** Encodes input into output (4 little endian 32 bit values). */
23static void encode(uint8_t output[16], const uint32_t input[4]);
24
25/** Encodes input into output (little endian 64 bit value). */
26static void encode(uint8_t output[8], const uint64_t input);
27
28/** Decodes input (4 little endian 32 bit values) into storage, if required. */
29static const uint32_t* decode(uint32_t storage[16], const uint8_t input[64]);
30
31SkMD5::SkMD5() : byteCount(0) {
32 // These are magic numbers from the specification.
33 this->state[0] = 0x67452301;
34 this->state[1] = 0xefcdab89;
35 this->state[2] = 0x98badcfe;
36 this->state[3] = 0x10325476;
37}
38
39bool SkMD5::write(const void* buf, size_t inputLength) {
40 const uint8_t* input = reinterpret_cast<const uint8_t*>(buf);
41 unsigned int bufferIndex = (unsigned int)(this->byteCount & 0x3F);
42 unsigned int bufferAvailable = 64 - bufferIndex;
43
44 unsigned int inputIndex;
45 if (inputLength >= bufferAvailable) {
46 if (bufferIndex) {
47 memcpy(&this->buffer[bufferIndex], input, bufferAvailable);
48 transform(this->state, this->buffer);
49 inputIndex = bufferAvailable;
50 } else {
51 inputIndex = 0;
52 }
53
54 for (; inputIndex + 63 < inputLength; inputIndex += 64) {
55 transform(this->state, &input[inputIndex]);
56 }
57
58 bufferIndex = 0;
59 } else {
60 inputIndex = 0;
61 }
62
63 memcpy(&this->buffer[bufferIndex], &input[inputIndex], inputLength - inputIndex);
64
65 this->byteCount += inputLength;
66 return true;
67}
68
69SkMD5::Digest SkMD5::finish() {
70 SkMD5::Digest digest;
71 // Get the number of bits before padding.
72 uint8_t bits[8];
73 encode(bits, this->byteCount << 3);
74
75 // Pad out to 56 mod 64.
76 unsigned int bufferIndex = (unsigned int)(this->byteCount & 0x3F);
77 unsigned int paddingLength = (bufferIndex < 56) ? (56 - bufferIndex) : (120 - bufferIndex);
78 static const uint8_t PADDING[64] = {
79 0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
80 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
81 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
82 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
83 };
84 (void)this->write(PADDING, paddingLength);
85
86 // Append length (length before padding, will cause final update).
87 (void)this->write(bits, 8);
88
89 // Write out digest.
90 encode(digest.data, this->state);
91
92#if defined(SK_MD5_CLEAR_DATA)
93 // Clear state.
94 memset(this, 0, sizeof(*this));
95#endif
96 return digest;
97}
98
99struct F { uint32_t operator()(uint32_t x, uint32_t y, uint32_t z) {
100 //return (x & y) | ((~x) & z);
101 return ((y ^ z) & x) ^ z; //equivelent but faster
102}};
103
104struct G { uint32_t operator()(uint32_t x, uint32_t y, uint32_t z) {
105 return (x & z) | (y & (~z));
106 //return ((x ^ y) & z) ^ y; //equivelent but slower
107}};
108
109struct H { uint32_t operator()(uint32_t x, uint32_t y, uint32_t z) {
110 return x ^ y ^ z;
111}};
112
113struct I { uint32_t operator()(uint32_t x, uint32_t y, uint32_t z) {
114 return y ^ (x | (~z));
115}};
116
117/** Rotates x left n bits. */
118static inline uint32_t rotate_left(uint32_t x, uint8_t n) {
119 return (x << n) | (x >> (32 - n));
120}
121
122template <typename T>
123static inline void operation(T operation, uint32_t& a, uint32_t b, uint32_t c, uint32_t d,
124 uint32_t x, uint8_t s, uint32_t t) {
125 a = b + rotate_left(a + operation(b, c, d) + x + t, s);
126}
127
128static void transform(uint32_t state[4], const uint8_t block[64]) {
129 uint32_t a = state[0], b = state[1], c = state[2], d = state[3];
130
131 uint32_t storage[16];
132 const uint32_t* X = decode(storage, block);
133
134 // Round 1
135 operation(F(), a, b, c, d, X[ 0], 7, 0xd76aa478); // 1
136 operation(F(), d, a, b, c, X[ 1], 12, 0xe8c7b756); // 2
137 operation(F(), c, d, a, b, X[ 2], 17, 0x242070db); // 3
138 operation(F(), b, c, d, a, X[ 3], 22, 0xc1bdceee); // 4
139 operation(F(), a, b, c, d, X[ 4], 7, 0xf57c0faf); // 5
140 operation(F(), d, a, b, c, X[ 5], 12, 0x4787c62a); // 6
141 operation(F(), c, d, a, b, X[ 6], 17, 0xa8304613); // 7
142 operation(F(), b, c, d, a, X[ 7], 22, 0xfd469501); // 8
143 operation(F(), a, b, c, d, X[ 8], 7, 0x698098d8); // 9
144 operation(F(), d, a, b, c, X[ 9], 12, 0x8b44f7af); // 10
145 operation(F(), c, d, a, b, X[10], 17, 0xffff5bb1); // 11
146 operation(F(), b, c, d, a, X[11], 22, 0x895cd7be); // 12
147 operation(F(), a, b, c, d, X[12], 7, 0x6b901122); // 13
148 operation(F(), d, a, b, c, X[13], 12, 0xfd987193); // 14
149 operation(F(), c, d, a, b, X[14], 17, 0xa679438e); // 15
150 operation(F(), b, c, d, a, X[15], 22, 0x49b40821); // 16
151
152 // Round 2
153 operation(G(), a, b, c, d, X[ 1], 5, 0xf61e2562); // 17
154 operation(G(), d, a, b, c, X[ 6], 9, 0xc040b340); // 18
155 operation(G(), c, d, a, b, X[11], 14, 0x265e5a51); // 19
156 operation(G(), b, c, d, a, X[ 0], 20, 0xe9b6c7aa); // 20
157 operation(G(), a, b, c, d, X[ 5], 5, 0xd62f105d); // 21
158 operation(G(), d, a, b, c, X[10], 9, 0x2441453); // 22
159 operation(G(), c, d, a, b, X[15], 14, 0xd8a1e681); // 23
160 operation(G(), b, c, d, a, X[ 4], 20, 0xe7d3fbc8); // 24
161 operation(G(), a, b, c, d, X[ 9], 5, 0x21e1cde6); // 25
162 operation(G(), d, a, b, c, X[14], 9, 0xc33707d6); // 26
163 operation(G(), c, d, a, b, X[ 3], 14, 0xf4d50d87); // 27
164 operation(G(), b, c, d, a, X[ 8], 20, 0x455a14ed); // 28
165 operation(G(), a, b, c, d, X[13], 5, 0xa9e3e905); // 29
166 operation(G(), d, a, b, c, X[ 2], 9, 0xfcefa3f8); // 30
167 operation(G(), c, d, a, b, X[ 7], 14, 0x676f02d9); // 31
168 operation(G(), b, c, d, a, X[12], 20, 0x8d2a4c8a); // 32
169
170 // Round 3
171 operation(H(), a, b, c, d, X[ 5], 4, 0xfffa3942); // 33
172 operation(H(), d, a, b, c, X[ 8], 11, 0x8771f681); // 34
173 operation(H(), c, d, a, b, X[11], 16, 0x6d9d6122); // 35
174 operation(H(), b, c, d, a, X[14], 23, 0xfde5380c); // 36
175 operation(H(), a, b, c, d, X[ 1], 4, 0xa4beea44); // 37
176 operation(H(), d, a, b, c, X[ 4], 11, 0x4bdecfa9); // 38
177 operation(H(), c, d, a, b, X[ 7], 16, 0xf6bb4b60); // 39
178 operation(H(), b, c, d, a, X[10], 23, 0xbebfbc70); // 40
179 operation(H(), a, b, c, d, X[13], 4, 0x289b7ec6); // 41
180 operation(H(), d, a, b, c, X[ 0], 11, 0xeaa127fa); // 42
181 operation(H(), c, d, a, b, X[ 3], 16, 0xd4ef3085); // 43
182 operation(H(), b, c, d, a, X[ 6], 23, 0x4881d05); // 44
183 operation(H(), a, b, c, d, X[ 9], 4, 0xd9d4d039); // 45
184 operation(H(), d, a, b, c, X[12], 11, 0xe6db99e5); // 46
185 operation(H(), c, d, a, b, X[15], 16, 0x1fa27cf8); // 47
186 operation(H(), b, c, d, a, X[ 2], 23, 0xc4ac5665); // 48
187
188 // Round 4
189 operation(I(), a, b, c, d, X[ 0], 6, 0xf4292244); // 49
190 operation(I(), d, a, b, c, X[ 7], 10, 0x432aff97); // 50
191 operation(I(), c, d, a, b, X[14], 15, 0xab9423a7); // 51
192 operation(I(), b, c, d, a, X[ 5], 21, 0xfc93a039); // 52
193 operation(I(), a, b, c, d, X[12], 6, 0x655b59c3); // 53
194 operation(I(), d, a, b, c, X[ 3], 10, 0x8f0ccc92); // 54
195 operation(I(), c, d, a, b, X[10], 15, 0xffeff47d); // 55
196 operation(I(), b, c, d, a, X[ 1], 21, 0x85845dd1); // 56
197 operation(I(), a, b, c, d, X[ 8], 6, 0x6fa87e4f); // 57
198 operation(I(), d, a, b, c, X[15], 10, 0xfe2ce6e0); // 58
199 operation(I(), c, d, a, b, X[ 6], 15, 0xa3014314); // 59
200 operation(I(), b, c, d, a, X[13], 21, 0x4e0811a1); // 60
201 operation(I(), a, b, c, d, X[ 4], 6, 0xf7537e82); // 61
202 operation(I(), d, a, b, c, X[11], 10, 0xbd3af235); // 62
203 operation(I(), c, d, a, b, X[ 2], 15, 0x2ad7d2bb); // 63
204 operation(I(), b, c, d, a, X[ 9], 21, 0xeb86d391); // 64
205
206 state[0] += a;
207 state[1] += b;
208 state[2] += c;
209 state[3] += d;
210
211#if defined(SK_MD5_CLEAR_DATA)
212 // Clear sensitive information.
213 if (X == &storage) {
214 memset(storage, 0, sizeof(storage));
215 }
216#endif
217}
218
219static void encode(uint8_t output[16], const uint32_t input[4]) {
220 for (size_t i = 0, j = 0; i < 4; i++, j += 4) {
221 output[j ] = (uint8_t) (input[i] & 0xff);
222 output[j+1] = (uint8_t)((input[i] >> 8) & 0xff);
223 output[j+2] = (uint8_t)((input[i] >> 16) & 0xff);
224 output[j+3] = (uint8_t)((input[i] >> 24) & 0xff);
225 }
226}
227
228static void encode(uint8_t output[8], const uint64_t input) {
229 output[0] = (uint8_t) (input & 0xff);
230 output[1] = (uint8_t)((input >> 8) & 0xff);
231 output[2] = (uint8_t)((input >> 16) & 0xff);
232 output[3] = (uint8_t)((input >> 24) & 0xff);
233 output[4] = (uint8_t)((input >> 32) & 0xff);
234 output[5] = (uint8_t)((input >> 40) & 0xff);
235 output[6] = (uint8_t)((input >> 48) & 0xff);
236 output[7] = (uint8_t)((input >> 56) & 0xff);
237}
238
239static inline bool is_aligned(const void *pointer, size_t byte_count) {
240 return reinterpret_cast<uintptr_t>(pointer) % byte_count == 0;
241}
242
243static const uint32_t* decode(uint32_t storage[16], const uint8_t input[64]) {
244#if defined(SK_CPU_LENDIAN) && defined(SK_CPU_FAST_UNALIGNED_ACCESS)
245 return reinterpret_cast<const uint32_t*>(input);
246#else
247#if defined(SK_CPU_LENDIAN)
248 if (is_aligned(input, 4)) {
249 return reinterpret_cast<const uint32_t*>(input);
250 }
251#endif
252 for (size_t i = 0, j = 0; j < 64; i++, j += 4) {
253 storage[i] = ((uint32_t)input[j ]) |
254 (((uint32_t)input[j+1]) << 8) |
255 (((uint32_t)input[j+2]) << 16) |
256 (((uint32_t)input[j+3]) << 24);
257 }
258 return storage;
259#endif
260}
261