用 C 写了个 md5 的程序
// 包含头文件#include <stdlib.h>
#include <stdio.h>
#include <string.h>
// 类型定义
typedef unsigned char uint8_t;
typedef unsigned int uint32_t;
typedef unsigned long long uint64_t;
// 常量定义
#define F(x, y, z) ((x & y) | (~x & z))
#define G(x, y, z) ((x & z) | ( y &~z))
#define H(x, y, z) (x^y^z)
#define I(x, y, z) (y^(x|~z))
// 内部函数
static uint32_t rotate_left(uint32_t x, int s) { return (x << s) | (x >> (32 - s)); }
static uint32_t FF(uint32_t *w, uint32_t x, int s, uint32_t t) { return (w[1] + rotate_left(w[0] + F(w[1], w[2], w[3]) + x + t, s)); }
static uint32_t GG(uint32_t *w, uint32_t x, int s, uint32_t t) { return (w[1] + rotate_left(w[0] + G(w[1], w[2], w[3]) + x + t, s)); }
static uint32_t HH(uint32_t *w, uint32_t x, int s, uint32_t t) { return (w[1] + rotate_left(w[0] + H(w[1], w[2], w[3]) + x + t, s)); }
static uint32_t II(uint32_t *w, uint32_t x, int s, uint32_t t) { return (w[1] + rotate_left(w[0] + I(w[1], w[2], w[3]) + x + t, s)); }
// 函数实现
void md5_digest(uint8_t md5[16], uint8_t *data, int len)
{
int hlen = len & ~0x3f;
int llen = len & 0x3f;
uint32_t W[4], WW[9], X[16], *MW, *t;
uint32_t padding_buf[32];
int padding_flag = llen < 56 ? 1 : 2;
int process_flag = 0;
int i, k;
uint8_t *psrc, *pend;
static uint32_t T[64] =
{
0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee, 0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501,
0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be, 0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821,
0xf61e2562, 0xc040b340, 0x265e5a51, 0xe9b6c7aa, 0xd62f105d, 0x02441453, 0xd8a1e681, 0xe7d3fbc8,
0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed, 0xa9e3e905, 0xfcefa3f8, 0x676f02d9, 0x8d2a4c8a,
0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c, 0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70,
0x289b7ec6, 0xeaa127fa, 0xd4ef3085, 0x04881d05, 0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665,
0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039, 0x655b59c3, 0x8f0ccc92, 0xffeff47d, 0x85845dd1,
0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1, 0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391,
};
static int SFF[4] = { 7, 12, 17, 22 };
static int SGG[4] = { 5, 9 , 14, 20 };
static int SHH[4] = { 4, 11, 16, 23 };
static int SII[4] = { 6, 10, 15, 21 };
// init W & MW
W[0] = 0x67452301; W[1] = 0xefcdab89; W[2] = 0x98badcfe; W[3] = 0x10325476;
MW = (uint32_t*)WW + 4;
// append padding bits & length to padding buffer
memcpy((uint8_t*)padding_buf + 0 , data + hlen, llen);
memset((uint8_t*)padding_buf + llen, 0 , 128 - llen);
((uint8_t *)padding_buf)[llen] = 0x80;
((uint64_t*)padding_buf)[8 * padding_flag - 1] = len * 8;
process_handler:
// init psrc, pend
if (!process_flag) { psrc = data; pend = psrc + hlen; }
else { psrc = (uint8_t*)padding_buf; pend = psrc + 64 * padding_flag; }
while (psrc < pend)
{
// copy 512 bits data into X.
memcpy(X, psrc, 64); psrc += 64;
// save W
for (i=0; i<4; i++) WW[i+0] = WW[i+4] = W[i];
t = T; // init t
for (i=0,k=0; i<16; i++,k+=1,k&=0xf) MW[-(i&3)] = MW[4-(i&3)] = FF(&(MW[-(i&3)]), X[k], SFF[i&3], *t++); // round 1
for (i=0,k=1; i<16; i++,k+=5,k&=0xf) MW[-(i&3)] = MW[4-(i&3)] = GG(&(MW[-(i&3)]), X[k], SGG[i&3], *t++); // round 2
for (i=0,k=5; i<16; i++,k+=3,k&=0xf) MW[-(i&3)] = MW[4-(i&3)] = HH(&(MW[-(i&3)]), X[k], SHH[i&3], *t++); // round 3
for (i=0,k=0; i<16; i++,k+=7,k&=0xf) MW[-(i&3)] = MW[4-(i&3)] = II(&(MW[-(i&3)]), X[k], SII[i&3], *t++); // round 4
// increase W
for (i=0; i<4; i++) W[i] += MW[i];
}
// goto process_handler if necessary
if (!process_flag) { process_flag = 1; goto process_handler; }
// copy result
memcpy(md5, W, 16);
}
int main(void)
{
uint8_t md5[16];
char *str = "abc";
int i;
md5_digest(md5, (uint8_t*)str, (int)strlen(str));
for (i=0; i<16; i++) printf("%02X", md5[i]); printf("\n");
getch();
return 0;
}
[ 本帖最后由 RockCarry 于 2014-11-19 16:07 编辑 ]
