xref: /third_party/skia/src/core/SkMD5.cpp (revision cb93a386) 
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