//MD5.cpp
#include <string>
std::string MD5(std::string s)
{
const char HEX_CHAR[]={'0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
const unsigned long Md5Calc_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
};
const unsigned long Md5Calc_s[ 16 ] = { 7,12,17,22,5, 9,14,20, 4,11,16,23,6,10,15,21 };
//擴展成K*512位
unsigned long *data;
int l;
l = s.length()*8;
data = new unsigned long[((l/512)+1)*512];
memset(data, 0, sizeof(data[0])*((l/512)+1)*512);
for(unsigned int i = 0; i < s.length(); ++i){
data[i / 4] |= s[i] << 8*((i % 4));
}
data[s.length() / 4] |= 0x80 << 8*((s.length()%4));
data[((l/512)+1)*512/32-2]=l;
l = (l/512)+1;
//開始計算
unsigned long H[4], a, b, c, d;
H[0]=0x67452301, H[1]=0xefcdab89, H[2]=0x98badcfe, H[3]=0x10325476;
for(int i = 0; i<l; ++i){
unsigned long M[16];
for(int t = 0; t<16; ++t)
M[t] = data[i*16+t];
a = H[0], b = H[1], c = H[2], d = H[3];
unsigned long s, k, x, e;
s = k = 0;
/** Turn 1, F */
s = k = 0;
for( x = 0; x < 16; x ++ ){
e = ( b & c ) | ( ~b & d );
e = a + e + M[ k ] + Md5Calc_t[ x ];
e = ( e >> ( 32 - Md5Calc_s[ s ] )) | ( e << Md5Calc_s[ s ] );
a = b + e;
e = d; d = c; c = b; b = a; a = e;
s = ( s + 1 ) % 4; k ++;
}
/** Turn 2, G */
k = 1; s = 4;
for( x = 16; x < 32; x ++ ){
e = ( b & d ) | ( c & ~d );
e = a + e + M[ k ] + Md5Calc_t[ x ];
e = ( e >> ( 32 - Md5Calc_s[ s ] )) | ( e << Md5Calc_s[ s ] );
a = b + e;
e = d; d = c; c = b; b = a; a = e;
k = ( k + 5 ) % 16;
s = ( s - 3 ) % 4 + 4;
}
/** Turn 3, H */
k = 5; s = 8;
for( x = 32; x < 48; x ++ ){
e = b ^ c ^ d;
e = a + e + M[ k ] + Md5Calc_t[ x ];
e = ( e >> ( 32 - Md5Calc_s[ s ] )) | ( e << Md5Calc_s[ s ] );
a = b + e;
e = d; d = c; c = b; b = a; a = e;
k = ( k + 3 ) % 16;
s = ( s - 7 ) % 4 + 8;
}
/** Turn 4, I */
k = 0; s = 12;
for( x = 48; x < 64; x ++ ){
e = c ^ ( b | ~d );
e = a + e + M[ k ] + Md5Calc_t[ x ];
e = ( e >> ( 32 - Md5Calc_s[ s ] )) | ( e << Md5Calc_s[ s ] );
a = b + e;
e = d; d = c; c = b; b = a; a = e;
k = ( k + 7 ) % 16;
s = ( s - 11 ) % 4 + 12;
}
H[0] += a;
H[1] += b;
H[2] += c;
H[3] += d;
}
char buf[33];
for(int i = 0; i<32; ++i){
buf[i] = HEX_CHAR[(H[i / 8] >> (4*((i % 8))))&0xf];
}
for(int i = 0; i<32; i += 2){
char tmp = buf[i];
buf[i] = buf[i+1];
buf[i+1] = tmp;
}
buf[32] = '\0';
return std::string(buf);
}
//Test
//#include <iostream>
//using namespace std;
//int main(int argc, char* argv[])
//{
// char s[100];
// std::string md5;
// while(true){
// scanf("%s", s);
// md5 = MD5(s);
// cout << md5 << endl;
// }
// return 0;
//}