michael@0: /*
michael@0:  * Copyright 2012 Google Inc.
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  *
michael@0:  * The following code is based on the description in RFC 1321.
michael@0:  * http://www.ietf.org/rfc/rfc1321.txt
michael@0:  */
michael@0: 
michael@0: #include "SkTypes.h"
michael@0: #include "SkMD5.h"
michael@0: #include <string.h>
michael@0: 
michael@0: /** MD5 basic transformation. Transforms state based on block. */
michael@0: static void transform(uint32_t state[4], const uint8_t block[64]);
michael@0: 
michael@0: /** Encodes input into output (4 little endian 32 bit values). */
michael@0: static void encode(uint8_t output[16], const uint32_t input[4]);
michael@0: 
michael@0: /** Encodes input into output (little endian 64 bit value). */
michael@0: static void encode(uint8_t output[8], const uint64_t input);
michael@0: 
michael@0: /** Decodes input (4 little endian 32 bit values) into storage, if required. */
michael@0: static const uint32_t* decode(uint32_t storage[16], const uint8_t input[64]);
michael@0: 
michael@0: SkMD5::SkMD5() : byteCount(0) {
michael@0:     // These are magic numbers from the specification.
michael@0:     this->state[0] = 0x67452301;
michael@0:     this->state[1] = 0xefcdab89;
michael@0:     this->state[2] = 0x98badcfe;
michael@0:     this->state[3] = 0x10325476;
michael@0: }
michael@0: 
michael@0: void SkMD5::update(const uint8_t* input, size_t inputLength) {
michael@0:     unsigned int bufferIndex = (unsigned int)(this->byteCount & 0x3F);
michael@0:     unsigned int bufferAvailable = 64 - bufferIndex;
michael@0: 
michael@0:     unsigned int inputIndex;
michael@0:     if (inputLength >= bufferAvailable) {
michael@0:         if (bufferIndex) {
michael@0:             memcpy(&this->buffer[bufferIndex], input, bufferAvailable);
michael@0:             transform(this->state, this->buffer);
michael@0:             inputIndex = bufferAvailable;
michael@0:         } else {
michael@0:             inputIndex = 0;
michael@0:         }
michael@0: 
michael@0:         for (; inputIndex + 63 < inputLength; inputIndex += 64) {
michael@0:             transform(this->state, &input[inputIndex]);
michael@0:         }
michael@0: 
michael@0:         bufferIndex = 0;
michael@0:     } else {
michael@0:         inputIndex = 0;
michael@0:     }
michael@0: 
michael@0:     memcpy(&this->buffer[bufferIndex], &input[inputIndex], inputLength - inputIndex);
michael@0: 
michael@0:     this->byteCount += inputLength;
michael@0: }
michael@0: 
michael@0: void SkMD5::finish(Digest& digest) {
michael@0:     // Get the number of bits before padding.
michael@0:     uint8_t bits[8];
michael@0:     encode(bits, this->byteCount << 3);
michael@0: 
michael@0:     // Pad out to 56 mod 64.
michael@0:     unsigned int bufferIndex = (unsigned int)(this->byteCount & 0x3F);
michael@0:     unsigned int paddingLength = (bufferIndex < 56) ? (56 - bufferIndex) : (120 - bufferIndex);
michael@0:     static uint8_t PADDING[64] = {
michael@0:         0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
michael@0:            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
michael@0:            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
michael@0:            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
michael@0:     };
michael@0:     this->update(PADDING, paddingLength);
michael@0: 
michael@0:     // Append length (length before padding, will cause final update).
michael@0:     this->update(bits, 8);
michael@0: 
michael@0:     // Write out digest.
michael@0:     encode(digest.data, this->state);
michael@0: 
michael@0: #if defined(SK_MD5_CLEAR_DATA)
michael@0:     // Clear state.
michael@0:     memset(this, 0, sizeof(*this));
michael@0: #endif
michael@0: }
michael@0: 
michael@0: struct F { uint32_t operator()(uint32_t x, uint32_t y, uint32_t z) {
michael@0:     //return (x & y) | ((~x) & z);
michael@0:     return ((y ^ z) & x) ^ z; //equivelent but faster
michael@0: }};
michael@0: 
michael@0: struct G { uint32_t operator()(uint32_t x, uint32_t y, uint32_t z) {
michael@0:     return (x & z) | (y & (~z));
michael@0:     //return ((x ^ y) & z) ^ y; //equivelent but slower
michael@0: }};
michael@0: 
michael@0: struct H { uint32_t operator()(uint32_t x, uint32_t y, uint32_t z) {
michael@0:     return x ^ y ^ z;
michael@0: }};
michael@0: 
michael@0: struct I { uint32_t operator()(uint32_t x, uint32_t y, uint32_t z) {
michael@0:     return y ^ (x | (~z));
michael@0: }};
michael@0: 
michael@0: /** Rotates x left n bits. */
michael@0: static inline uint32_t rotate_left(uint32_t x, uint8_t n) {
michael@0:     return (x << n) | (x >> (32 - n));
michael@0: }
michael@0: 
michael@0: template <typename T>
michael@0: static inline void operation(T operation, uint32_t& a, uint32_t b, uint32_t c, uint32_t d,
michael@0:                              uint32_t x, uint8_t s, uint32_t t) {
michael@0:     a = b + rotate_left(a + operation(b, c, d) + x + t, s);
michael@0: }
michael@0: 
michael@0: static void transform(uint32_t state[4], const uint8_t block[64]) {
michael@0:     uint32_t a = state[0], b = state[1], c = state[2], d = state[3];
michael@0: 
michael@0:     uint32_t storage[16];
michael@0:     const uint32_t* X = decode(storage, block);
michael@0: 
michael@0:     // Round 1
michael@0:     operation(F(), a, b, c, d, X[ 0],  7, 0xd76aa478); // 1
michael@0:     operation(F(), d, a, b, c, X[ 1], 12, 0xe8c7b756); // 2
michael@0:     operation(F(), c, d, a, b, X[ 2], 17, 0x242070db); // 3
michael@0:     operation(F(), b, c, d, a, X[ 3], 22, 0xc1bdceee); // 4
michael@0:     operation(F(), a, b, c, d, X[ 4],  7, 0xf57c0faf); // 5
michael@0:     operation(F(), d, a, b, c, X[ 5], 12, 0x4787c62a); // 6
michael@0:     operation(F(), c, d, a, b, X[ 6], 17, 0xa8304613); // 7
michael@0:     operation(F(), b, c, d, a, X[ 7], 22, 0xfd469501); // 8
michael@0:     operation(F(), a, b, c, d, X[ 8],  7, 0x698098d8); // 9
michael@0:     operation(F(), d, a, b, c, X[ 9], 12, 0x8b44f7af); // 10
michael@0:     operation(F(), c, d, a, b, X[10], 17, 0xffff5bb1); // 11
michael@0:     operation(F(), b, c, d, a, X[11], 22, 0x895cd7be); // 12
michael@0:     operation(F(), a, b, c, d, X[12],  7, 0x6b901122); // 13
michael@0:     operation(F(), d, a, b, c, X[13], 12, 0xfd987193); // 14
michael@0:     operation(F(), c, d, a, b, X[14], 17, 0xa679438e); // 15
michael@0:     operation(F(), b, c, d, a, X[15], 22, 0x49b40821); // 16
michael@0: 
michael@0:     // Round 2
michael@0:     operation(G(), a, b, c, d, X[ 1],  5, 0xf61e2562); // 17
michael@0:     operation(G(), d, a, b, c, X[ 6],  9, 0xc040b340); // 18
michael@0:     operation(G(), c, d, a, b, X[11], 14, 0x265e5a51); // 19
michael@0:     operation(G(), b, c, d, a, X[ 0], 20, 0xe9b6c7aa); // 20
michael@0:     operation(G(), a, b, c, d, X[ 5],  5, 0xd62f105d); // 21
michael@0:     operation(G(), d, a, b, c, X[10],  9,  0x2441453); // 22
michael@0:     operation(G(), c, d, a, b, X[15], 14, 0xd8a1e681); // 23
michael@0:     operation(G(), b, c, d, a, X[ 4], 20, 0xe7d3fbc8); // 24
michael@0:     operation(G(), a, b, c, d, X[ 9],  5, 0x21e1cde6); // 25
michael@0:     operation(G(), d, a, b, c, X[14],  9, 0xc33707d6); // 26
michael@0:     operation(G(), c, d, a, b, X[ 3], 14, 0xf4d50d87); // 27
michael@0:     operation(G(), b, c, d, a, X[ 8], 20, 0x455a14ed); // 28
michael@0:     operation(G(), a, b, c, d, X[13],  5, 0xa9e3e905); // 29
michael@0:     operation(G(), d, a, b, c, X[ 2],  9, 0xfcefa3f8); // 30
michael@0:     operation(G(), c, d, a, b, X[ 7], 14, 0x676f02d9); // 31
michael@0:     operation(G(), b, c, d, a, X[12], 20, 0x8d2a4c8a); // 32
michael@0: 
michael@0:     // Round 3
michael@0:     operation(H(), a, b, c, d, X[ 5],  4, 0xfffa3942); // 33
michael@0:     operation(H(), d, a, b, c, X[ 8], 11, 0x8771f681); // 34
michael@0:     operation(H(), c, d, a, b, X[11], 16, 0x6d9d6122); // 35
michael@0:     operation(H(), b, c, d, a, X[14], 23, 0xfde5380c); // 36
michael@0:     operation(H(), a, b, c, d, X[ 1],  4, 0xa4beea44); // 37
michael@0:     operation(H(), d, a, b, c, X[ 4], 11, 0x4bdecfa9); // 38
michael@0:     operation(H(), c, d, a, b, X[ 7], 16, 0xf6bb4b60); // 39
michael@0:     operation(H(), b, c, d, a, X[10], 23, 0xbebfbc70); // 40
michael@0:     operation(H(), a, b, c, d, X[13],  4, 0x289b7ec6); // 41
michael@0:     operation(H(), d, a, b, c, X[ 0], 11, 0xeaa127fa); // 42
michael@0:     operation(H(), c, d, a, b, X[ 3], 16, 0xd4ef3085); // 43
michael@0:     operation(H(), b, c, d, a, X[ 6], 23,  0x4881d05); // 44
michael@0:     operation(H(), a, b, c, d, X[ 9],  4, 0xd9d4d039); // 45
michael@0:     operation(H(), d, a, b, c, X[12], 11, 0xe6db99e5); // 46
michael@0:     operation(H(), c, d, a, b, X[15], 16, 0x1fa27cf8); // 47
michael@0:     operation(H(), b, c, d, a, X[ 2], 23, 0xc4ac5665); // 48
michael@0: 
michael@0:     // Round 4
michael@0:     operation(I(), a, b, c, d, X[ 0],  6, 0xf4292244); // 49
michael@0:     operation(I(), d, a, b, c, X[ 7], 10, 0x432aff97); // 50
michael@0:     operation(I(), c, d, a, b, X[14], 15, 0xab9423a7); // 51
michael@0:     operation(I(), b, c, d, a, X[ 5], 21, 0xfc93a039); // 52
michael@0:     operation(I(), a, b, c, d, X[12],  6, 0x655b59c3); // 53
michael@0:     operation(I(), d, a, b, c, X[ 3], 10, 0x8f0ccc92); // 54
michael@0:     operation(I(), c, d, a, b, X[10], 15, 0xffeff47d); // 55
michael@0:     operation(I(), b, c, d, a, X[ 1], 21, 0x85845dd1); // 56
michael@0:     operation(I(), a, b, c, d, X[ 8],  6, 0x6fa87e4f); // 57
michael@0:     operation(I(), d, a, b, c, X[15], 10, 0xfe2ce6e0); // 58
michael@0:     operation(I(), c, d, a, b, X[ 6], 15, 0xa3014314); // 59
michael@0:     operation(I(), b, c, d, a, X[13], 21, 0x4e0811a1); // 60
michael@0:     operation(I(), a, b, c, d, X[ 4],  6, 0xf7537e82); // 61
michael@0:     operation(I(), d, a, b, c, X[11], 10, 0xbd3af235); // 62
michael@0:     operation(I(), c, d, a, b, X[ 2], 15, 0x2ad7d2bb); // 63
michael@0:     operation(I(), b, c, d, a, X[ 9], 21, 0xeb86d391); // 64
michael@0: 
michael@0:     state[0] += a;
michael@0:     state[1] += b;
michael@0:     state[2] += c;
michael@0:     state[3] += d;
michael@0: 
michael@0: #if defined(SK_MD5_CLEAR_DATA)
michael@0:     // Clear sensitive information.
michael@0:     if (X == &storage) {
michael@0:         memset(storage, 0, sizeof(storage));
michael@0:     }
michael@0: #endif
michael@0: }
michael@0: 
michael@0: static void encode(uint8_t output[16], const uint32_t input[4]) {
michael@0:     for (size_t i = 0, j = 0; i < 4; i++, j += 4) {
michael@0:         output[j  ] = (uint8_t) (input[i]        & 0xff);
michael@0:         output[j+1] = (uint8_t)((input[i] >>  8) & 0xff);
michael@0:         output[j+2] = (uint8_t)((input[i] >> 16) & 0xff);
michael@0:         output[j+3] = (uint8_t)((input[i] >> 24) & 0xff);
michael@0:     }
michael@0: }
michael@0: 
michael@0: static void encode(uint8_t output[8], const uint64_t input) {
michael@0:     output[0] = (uint8_t) (input        & 0xff);
michael@0:     output[1] = (uint8_t)((input >>  8) & 0xff);
michael@0:     output[2] = (uint8_t)((input >> 16) & 0xff);
michael@0:     output[3] = (uint8_t)((input >> 24) & 0xff);
michael@0:     output[4] = (uint8_t)((input >> 32) & 0xff);
michael@0:     output[5] = (uint8_t)((input >> 40) & 0xff);
michael@0:     output[6] = (uint8_t)((input >> 48) & 0xff);
michael@0:     output[7] = (uint8_t)((input >> 56) & 0xff);
michael@0: }
michael@0: 
michael@0: static inline bool is_aligned(const void *pointer, size_t byte_count) {
michael@0:     return reinterpret_cast<uintptr_t>(pointer) % byte_count == 0;
michael@0: }
michael@0: 
michael@0: static const uint32_t* decode(uint32_t storage[16], const uint8_t input[64]) {
michael@0: #if defined(SK_CPU_LENDIAN) && defined(SK_CPU_FAST_UNALIGNED_ACCESS)
michael@0:    return reinterpret_cast<const uint32_t*>(input);
michael@0: #else
michael@0: #if defined(SK_CPU_LENDIAN)
michael@0:     if (is_aligned(input, 4)) {
michael@0:         return reinterpret_cast<const uint32_t*>(input);
michael@0:     }
michael@0: #endif
michael@0:     for (size_t i = 0, j = 0; j < 64; i++, j += 4) {
michael@0:         storage[i] =  ((uint32_t)input[j  ])        |
michael@0:                      (((uint32_t)input[j+1]) <<  8) |
michael@0:                      (((uint32_t)input[j+2]) << 16) |
michael@0:                      (((uint32_t)input[j+3]) << 24);
michael@0:     }
michael@0:     return storage;
michael@0: #endif
michael@0: }