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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. */
20 static void transform(uint32_t state[4], const uint8_t block[64]);
21 
22 /** Encodes input into output (4 little endian 32 bit values). */
23 static void encode(uint8_t output[16], const uint32_t input[4]);
24 
25 /** Encodes input into output (little endian 64 bit value). */
26 static void encode(uint8_t output[8], const uint64_t input);
27 
28 /** Decodes input (4 little endian 32 bit values) into storage, if required. */
29 static const uint32_t* decode(uint32_t storage[16], const uint8_t input[64]);
30 
SkMD5()31 SkMD5::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 
write(const void * buf,size_t inputLength)39 bool 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 
finish()69 SkMD5::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 
operator ()F99 struct 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 
operator ()G104 struct 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 
operator ()H109 struct H { uint32_t operator()(uint32_t x, uint32_t y, uint32_t z) {
110     return x ^ y ^ z;
111 }};
112 
operator ()I113 struct 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. */
rotate_left(uint32_t x,uint8_t n)118 static inline uint32_t rotate_left(uint32_t x, uint8_t n) {
119     return (x << n) | (x >> (32 - n));
120 }
121 
122 template <typename T>
operation(T operation,uint32_t & a,uint32_t b,uint32_t c,uint32_t d,uint32_t x,uint8_t s,uint32_t t)123 static 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 
transform(uint32_t state[4],const uint8_t block[64])128 static 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 
encode(uint8_t output[16],const uint32_t input[4])219 static 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 
encode(uint8_t output[8],const uint64_t input)228 static 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 
is_aligned(const void * pointer,size_t byte_count)239 static inline bool is_aligned(const void *pointer, size_t byte_count) {
240     return reinterpret_cast<uintptr_t>(pointer) % byte_count == 0;
241 }
242 
decode(uint32_t storage[16],const uint8_t input[64])243 static 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