#include <stdio.h>
#include <string.h>
#include <stdint.h>
#define rol(x, n) ( ((x) << (n)) | ((x) >> (32-(n))) )
#define FF(b, c, d) (d ^ (b & (c ^ d)))
#define FG(b, c, d) FF (d, b, c)
#define FH(b, c, d) (b ^ c ^ d)
#define FI(b, c, d) (c ^ (b | ~d))
uint32_t cvt32(uint32_t i)
{
union {
uint32_t u;
uint8_t c[4];
} a, b;
b.u = i;
int n = 4;
while(n--)
a.c[n] = b.c[3-n];
return a.u;
}
uint64_t cvt64(uint64_t i)
{
union {
uint64_t u;
uint8_t c[8];
} a, b;
b.u = i;
int n = 8;
while(n--)
a.c[n] = b.c[7-n];
return a.u;
}
int is_big_endian;
void judge_endian()
{
union {
int i;
char c;
} u;
u.i = 1;
is_big_endian = (u.c == 0);
}
void md5_calc(uint32_t abcd[4], uint32_t data[16])
{
uint32_t correct_words[16];
int i;
if(is_big_endian) {
for(i = 0; i < 16; i++)
correct_words[i] = cvt32(data[i]);
} else {
memcpy(correct_words, data, 64);
}
uint32_t * cwp = correct_words;
uint32_t A = abcd[0];
uint32_t B = abcd[1];
uint32_t C = abcd[2];
uint32_t D = abcd[3];
#define OP(a, b, c, d, s, T) do { a += FF (b, c, d) + (*cwp++) + T; a = rol(a, s); a += b; } while (0)
/* Round 1. */
OP (A, B, C, D, 7, 0xd76aa478);
OP (D, A, B, C, 12, 0xe8c7b756);
OP (C, D, A, B, 17, 0x242070db);
OP (B, C, D, A, 22, 0xc1bdceee);
OP (A, B, C, D, 7, 0xf57c0faf);
OP (D, A, B, C, 12, 0x4787c62a);
OP (C, D, A, B, 17, 0xa8304613);
OP (B, C, D, A, 22, 0xfd469501);
OP (A, B, C, D, 7, 0x698098d8);
OP (D, A, B, C, 12, 0x8b44f7af);
OP (C, D, A, B, 17, 0xffff5bb1);
OP (B, C, D, A, 22, 0x895cd7be);
OP (A, B, C, D, 7, 0x6b901122);
OP (D, A, B, C, 12, 0xfd987193);
OP (C, D, A, B, 17, 0xa679438e);
OP (B, C, D, A, 22, 0x49b40821);
#undef OP
#define OP(f, a, b, c, d, k, s, T) do { a += f (b, c, d) + correct_words[k] + T; a = rol(a, s); a += b; } while (0)
/* Round 2. */
OP (FG, A, B, C, D, 1, 5, 0xf61e2562);
OP (FG, D, A, B, C, 6, 9, 0xc040b340);
OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
OP (FG, B, C, D, A, 0, 20, 0xe9b6c7aa);
OP (FG, A, B, C, D, 5, 5, 0xd62f105d);
OP (FG, D, A, B, C, 10, 9, 0x02441453);
OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
OP (FG, B, C, D, A, 4, 20, 0xe7d3fbc8);
OP (FG, A, B, C, D, 9, 5, 0x21e1cde6);
OP (FG, D, A, B, C, 14, 9, 0xc33707d6);
OP (FG, C, D, A, B, 3, 14, 0xf4d50d87);
OP (FG, B, C, D, A, 8, 20, 0x455a14ed);
OP (FG, A, B, C, D, 13, 5, 0xa9e3e905);
OP (FG, D, A, B, C, 2, 9, 0xfcefa3f8);
OP (FG, C, D, A, B, 7, 14, 0x676f02d9);
OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);
/* Round 3. */
OP (FH, A, B, C, D, 5, 4, 0xfffa3942);
OP (FH, D, A, B, C, 8, 11, 0x8771f681);
OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
OP (FH, A, B, C, D, 1, 4, 0xa4beea44);
OP (FH, D, A, B, C, 4, 11, 0x4bdecfa9);
OP (FH, C, D, A, B, 7, 16, 0xf6bb4b60);
OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
OP (FH, A, B, C, D, 13, 4, 0x289b7ec6);
OP (FH, D, A, B, C, 0, 11, 0xeaa127fa);
OP (FH, C, D, A, B, 3, 16, 0xd4ef3085);
OP (FH, B, C, D, A, 6, 23, 0x04881d05);
OP (FH, A, B, C, D, 9, 4, 0xd9d4d039);
OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
OP (FH, B, C, D, A, 2, 23, 0xc4ac5665);
/* Round 4. */
OP (FI, A, B, C, D, 0, 6, 0xf4292244);
OP (FI, D, A, B, C, 7, 10, 0x432aff97);
OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
OP (FI, B, C, D, A, 5, 21, 0xfc93a039);
OP (FI, A, B, C, D, 12, 6, 0x655b59c3);
OP (FI, D, A, B, C, 3, 10, 0x8f0ccc92);
OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
OP (FI, B, C, D, A, 1, 21, 0x85845dd1);
OP (FI, A, B, C, D, 8, 6, 0x6fa87e4f);
OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
OP (FI, C, D, A, B, 6, 15, 0xa3014314);
OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
OP (FI, A, B, C, D, 4, 6, 0xf7537e82);
OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
OP (FI, C, D, A, B, 2, 15, 0x2ad7d2bb);
OP (FI, B, C, D, A, 9, 21, 0xeb86d391);
abcd[0] += A;
abcd[1] += B;
abcd[2] += C;
abcd[3] += D;
}
int main(int argc, char * argv[])
{
judge_endian();
if(argc != 2)
return 1;
FILE * f = fopen(argv[1], "rb");
if(!f)
return 2;
uint32_t abcd[4] = { 0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476 };
uint64_t bit_sum = 0;
for(;;) {
char buf[128];
size_t n = fread(buf, 1, 64, f);
bit_sum += n * 8;
if(n == 64) {
md5_calc(abcd, (void *)buf);
} else {
memset(buf + n, 0, 128 - n);
buf[n] = 0x80;
uint64_t * end = (void *)( n < 56 ? &buf[64] : &buf[128]);
end[-1] = is_big_endian ? cvt64(bit_sum) : bit_sum;
md5_calc(abcd, (void *)buf);
if(n >= 56)
md5_calc(abcd, (void *)&buf[64]);
break;
}
}
fclose(f);
int i;
for(i = 0; i < 4; i++)
printf("%08x", cvt32(abcd[i]));
printf("\n");
return 0;
}
原文：http://my.oschina.net/2bit/blog/511588