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