纯C MD5计算

代码是从网上找的，具体来源找不到了，在找来的代码上改了内存泄漏和改成纯C实现。
.c

#include<string.h>#include <stdio.h>   #include <stdlib.h>   #include <memory.h>   #include <math.h>   typedef unsigned char BYTE;typedef unsigned int  UINT;typedef UINT MD5_SUB_ARRAY[16];typedef UINT MD5_TRANSORM_FUNC(UINT, UINT, UINT);typedef struct{    UINT    a;    UINT    b;    UINT    c;    UINT    d;    MD5_SUB_ARRAY   sub_array;}MD5_TRANSFORM_PARAM;const double    MAX_INT = (double)0xFFFFFFFF + 1.0;const UINT MD5_TRANSFORM_MATRIX[4][16][3] ={    {        { 0, 7, 1 },{ 1,12, 2 },{ 2,17, 3 },{ 3,22, 4 },        { 4, 7, 5 },{ 5,12, 6 },{ 6,17, 7 },{ 7,22, 8 },        { 8, 7, 9 },{ 9,12,10 },{ 10,17,11 },{ 11,22,12 },        { 12, 7,13 },{ 13,12,14 },{ 14,17,15 },{ 15,22,16 },    },    {        { 1, 5,17 },{ 6, 9,18 },{ 11,14,19 },{ 0,20,20 },        { 5, 5,21 },{ 10, 9,22 },{ 15,14,23 },{ 4,20,24 },        { 9, 5,25 },{ 14, 9,26 },{ 3,14,27 },{ 8,20,28 },        { 13, 5,29 },{ 2, 9,30 },{ 7,14,31 },{ 12,20,32 },    },    {        { 5, 4, 33 },{ 8,11,34 },{ 11,16,35 },{ 14, 23,36 },        { 1, 4, 37 },{ 4,11,38 },{ 7,16,39 },{ 10, 23,40 },        { 13,4, 41 },{ 0,11,42 },{ 3,16,43 },{ 6, 23,44 },        { 9, 4, 45 },{ 12,11,46 },{ 15,16,47 },{ 2, 23,48 },    },    {        { 0,6,49 },{ 7,10,50 },{ 14,15,51 },{ 5, 21,52 },        { 12,6,53 },{ 3,10,54 },{ 10,15,55 },{ 1, 21,56 },        { 8,6,57 },{ 15,10,58 },{ 6,15,59 },{ 13, 21,60 },        { 4,6,61 },{ 11,10,62 },{ 2,15,63 },{ 9, 21,64 },    },};static UINT MD5_TRANSFORM_ARRAY[65];void MD5_Init(){    int x;    for (x = 1; x <= 64; x++)    {        MD5_TRANSFORM_ARRAY[x] = (UINT)(MAX_INT * fabs(sin(x)));    }}UINT F(UINT x, UINT y, UINT z){    return ((x & y) | ((~x) & z));}UINT G(UINT x, UINT y, UINT z){    return ((x & z) | (y & (~z)));}UINT H(UINT x, UINT y, UINT z){    return (x ^ y ^ z);}UINT I(UINT x, UINT y, UINT z){    return (y ^ (x | (~z)));}BYTE* MD5_prepare_data(const BYTE* data, int len, int* new_len){    int rest, fill, size;    BYTE* new_data;    UINT  bit_len;    // (1) 字节补齐       rest = len % 56;    if (rest <= 56) fill = 56 - rest;    else fill = (64 - rest) + 56;    new_data = (BYTE*)malloc(len + fill + 8);    if (NULL == new_data) return NULL;    if (len > 0)    memcpy(new_data, data, len);    if (fill > 0)   memset(new_data + len, 0x80, 1);    if (fill > 1)   memset(new_data + len + 1, 0, fill - 1);    size = fill + len;    // (2) 附加数据的比特长度       bit_len = len * 8;    // (64位二进制数表示的)比特长度的低32位       memset(new_data + size + 0, (bit_len & 0x000000FF), 1);    memset(new_data + size + 1, (bit_len & 0x0000FF00) >> 8, 1);    memset(new_data + size + 2, (bit_len & 0x00FF0000) >> 16, 1);    memset(new_data + size + 3, (bit_len & 0xFF000000) >> 24, 1);    // 不考虑比特长度超出32位无符号数表示范围,所以高32位总是0       memset(new_data + size + 4, 0, 4);    *new_len = size + 8;    return new_data;}void MD5_transform(MD5_TRANSFORM_PARAM* param, int ring, MD5_TRANSORM_FUNC func){    UINT a, b, c, d, s, k, i;    UINT abcd[4];    UINT *X, *T;    int index;    abcd[0] = param->a;    abcd[1] = param->b;    abcd[2] = param->c;    abcd[3] = param->d;    X = param->sub_array;    T = MD5_TRANSFORM_ARRAY;    for (index = 0; index < 16; index++)    {        a = abcd[(3 * index + 0) % 4];        b = abcd[(3 * index + 1) % 4];        c = abcd[(3 * index + 2) % 4];        d = abcd[(3 * index + 3) % 4];        k = MD5_TRANSFORM_MATRIX[ring][index][0];        s = MD5_TRANSFORM_MATRIX[ring][index][1];        i = MD5_TRANSFORM_MATRIX[ring][index][2];        a = a + func(b, c, d) + X[k] + T[i];        a = (a << s) | (a >> (32 - s)); // 循环左移           a = a + b;        abcd[(3 * index + 0) % 4] = a;    }    param->a = abcd[0];    param->b = abcd[1];    param->c = abcd[2];    param->d = abcd[3];}int MD5(const BYTE* data, int len, char*dst){    int  x, y, new_len;    MD5_TRANSFORM_PARAM param;    UINT AA, BB, CC, DD;    BYTE* buf;    MD5_Init();    buf = MD5_prepare_data(data, len, &new_len);    if (buf == NULL) return -1;    AA = 0x67452301;    BB = 0xefcdab89;    CC = 0x98badcfe;    DD = 0x10325476;    for (x = 0; x < new_len / 64; x++)    {        param.a = AA;        param.b = BB;        param.c = CC;        param.d = DD;        for (y = 0; y < 16; y++)        {            param.sub_array[y] = buf[64 * x + 4 * y + 0];            param.sub_array[y] += buf[64 * x + 4 * y + 1] << 8;            param.sub_array[y] += buf[64 * x + 4 * y + 2] << 16;            param.sub_array[y] += buf[64 * x + 4 * y + 3] << 24;        }        MD5_transform(&param, 0, F);        MD5_transform(&param, 1, G);        MD5_transform(&param, 2, H);        MD5_transform(&param, 3, I);        AA += param.a;        BB += param.b;        CC += param.c;        DD += param.d;    }    //printf("MD5(\"%s\")=", data);        //格式化    sprintf(dst, "%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X",        (AA & 0x000000FF),        (AA & 0x0000FF00) >> 8,        (AA & 0x00FF0000) >> 16,        (AA & 0xFF000000) >> 24,        (BB & 0x000000FF),        (BB & 0x0000FF00) >> 8,        (BB & 0x00FF0000) >> 16,        (BB & 0xFF000000) >> 24,        (CC & 0x000000FF),        (CC & 0x0000FF00) >> 8,        (CC & 0x00FF0000) >> 16,        (CC & 0xFF000000) >> 24,        (DD & 0x000000FF),        (DD & 0x0000FF00) >> 8,        (DD & 0x00FF0000) >> 16,        (DD & 0xFF000000) >> 24);    free(buf);    buf = NULL;    return 0;}

使用时：

    char buf[]="asc";    int len=strlen(buf);    char dst[33]={0};    MD5(buf,len,dst);    printf("%s",dst);