md5 算法 说明 以及 c源代码

1、MD5算法是对输入的数据进行补位，使得如果数据位长度LEN对512求余的结果是448。即数据扩展至K*512+448位。即K*64+56个字节，K为整数。 具体补位操作：补一个1，然后补0至满足上述要求

2、补数据长度：
用一个64位的数字表示数据的原始长度B，把B用两个32位数表示。这时，数据就被填补成长度为512位的倍数。

3. 初始化MD5参数
四个32位整数 (A,B,C,D) 用来计算信息摘要，初始化使用的是十六进制表示的数字
A=0X01234567
B=0X89abcdef
C=0Xfedcba98
D=0X76543210

4、处理位操作函数
X，Y，Z为32位整数。
F(X,Y,Z) = X&Y|NOT(X)&Z
G(X,Y,Z) = X&Z|Y&not(Z)
H(X,Y,Z) = X xor Y xor Z
I(X,Y,Z) = Y xor (X|not(Z))

5、主要变换过程：
使用常数组T[1 ... 64]， T[i]为32位整数用16进制表示，数据用16个32位的整数数组M[]表示。
具体过程如下：
/* 处理数据原文 */
For i = 0 to N/16-1 do
/*每一次，把数据原文存放在16个元素的数组X中. */
For j = 0 to 15 do
Set X[j] to M[i*16+j].
end /结束对J的循环
/* Save A as AA, B as BB, C as CC, and D as DD. */
AA = A
BB = B
CC = C
DD = D
/* 第1轮*/
/* 以 [abcd k s i]表示如下操作
a = b + ((a + F(b,c,d) + X[k] + T[i]) <<< s). */
/* Do the following 16 operations. */
[ABCD 0 7 1] [DABC 1 12 2] [CDAB 2 17 3] [BCDA 3 22 4]
[ABCD 4 7 5] [DABC 5 12 6] [CDAB 6 17 7] [BCDA 7 22 8]
[ABCD 8 7 9] [DABC 9 12 10] [CDAB 10 17 11] [BCDA 11 22 12]
[ABCD 12 7 13] [DABC 13 12 14] [CDAB 14 17 15] [BCDA 15 22 16]
/* 第2轮* */
/* 以 [abcd k s i]表示如下操作
a = b + ((a + G(b,c,d) + X[k] + T[i]) <<< s). */
/* Do the following 16 operations. */
[ABCD 1 5 17] [DABC 6 9 18] [CDAB 11 14 19] [BCDA 0 20 20]
[ABCD 5 5 21] [DABC 10 9 22] [CDAB 15 14 23] [BCDA 4 20 24]
[ABCD 9 5 25] [DABC 14 9 26] [CDAB 3 14 27] [BCDA 8 20 28]
[ABCD 13 5 29] [DABC 2 9 30] [CDAB 7 14 31] [BCDA 12 20 32]
/* 第3轮*/
/* 以 [abcd k s i]表示如下操作
a = b + ((a + H(b,c,d) + X[k] + T[i]) <<< s). */
/* Do the following 16 operations. */
[ABCD 5 4 33] [DABC 8 11 34] [CDAB 11 16 35] [BCDA 14 23 36]
[ABCD 1 4 37] [DABC 4 11 38] [CDAB 7 16 39] [BCDA 10 23 40]
[ABCD 13 4 41] [DABC 0 11 42] [CDAB 3 16 43] [BCDA 6 23 44]
[ABCD 9 4 45] [DABC 12 11 46] [CDAB 15 16 47] [BCDA 2 23 48]
/* 第4轮*/
/* 以 [abcd k s i]表示如下操作
a = b + ((a + I(b,c,d) + X[k] + T[i]) <<< s). */
/* Do the following 16 operations. */
[ABCD 0 6 49] [DABC 7 10 50] [CDAB 14 15 51] [BCDA 5 21 52]
[ABCD 12 6 53] [DABC 3 10 54] [CDAB 10 15 55] [BCDA 1 21 56]
[ABCD 8 6 57] [DABC 15 10 58] [CDAB 6 15 59] [BCDA 13 21 60]
[ABCD 4 6 61] [DABC 11 10 62] [CDAB 2 15 63] [BCDA 9 21 64]
/* 然后进行如下操作 */
A = A + AA
B = B + BB
C = C + CC
D = D + DD
end /* 结束对I的循环*/

源代码：

 

md5.h


#ifndef _RPCENG_MD5_H
#define _RPCENG_MD5_H

#include <string>

typedef struct 
...{
    unsigned int state[4];      
    unsigned int count[2];      
    unsigned char buffer[64];      
} MD5Context;

void MD5_Init(MD5Context * context);

void MD5_Update(MD5Context * context, unsigned char * buf, int len);

void MD5_Final(MD5Context * context, unsigned char digest[16]);

bool MD5_File ( const char * filename,unsigned char *buff );

bool MD5_File ( const char * filename,std::string& md5str );

#endif /* end of _RPCENG_MD5_H */








md5.cpp

#include <stdio.h>
#include <string.h>
#include "md5.h"

#define S11 7
#define S12 12
#define S13 17
#define S14 22
#define S21 5
#define S22 9
#define S23 14
#define S24 20
#define S31 4
#define S32 11
#define S33 16
#define S34 23
#define S41 6
#define S42 10
#define S43 15
#define S44 21

static unsigned char 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
};

#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)))

#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

#define FF(a, b, c, d, x, s, ac)    /
{   /
    (a) += F((b), (c), (d)) + (x) + (unsigned int)(ac);    /
    (a) = ROTATE_LEFT((a), (s));    /
    (a) += (b);    /
}
#define GG(a, b, c, d, x, s, ac)    /
{     /
    (a) += G((b), (c), (d)) + (x) + (unsigned int)(ac);  /
    (a) = ROTATE_LEFT((a), (s));    /
    (a) += (b);    /
}
#define HH(a, b, c, d, x, s, ac)    /
{    /
    (a) += H((b), (c), (d)) + (x) + (unsigned int)(ac);    /
    (a) = ROTATE_LEFT((a), (s));    /
    (a) += (b);    /
}
#define II(a, b, c, d, x, s, ac)    /
{    /
    (a) += I((b), (c), (d)) + (x) + (unsigned int)(ac);  /
    (a) = ROTATE_LEFT((a), (s));    /
    (a) += (b);     /
}
static void MD5_Encode(unsigned char * output, unsigned int * input, int len)
...{
    unsigned int i, j;
    for (i = 0, j = 0; j < len; i++, j += 4)
    ...{
        output[j] = (unsigned char) (input[i] & 0xff);
        output[j + 1] = (unsigned char) ((input[i] >> 8) & 0xff);
        output[j + 2] = (unsigned char) ((input[i] >> 16) & 0xff);
        output[j + 3] = (unsigned char) ((input[i] >> 24) & 0xff);
    }
}

static void MD5_Decode(unsigned int * output, unsigned char * input, int len)
...{
    unsigned int i, j;
    for (i = 0, j = 0; j < len; i++, j += 4)
    ...{
        output[i] = ((unsigned int) input[j]) |
            (((unsigned int) input[j + 1]) << 8) |
            (((unsigned int) input[j + 2]) << 16) |
            (((unsigned int) input[j + 3]) << 24);
    }
}

static void MD5_Transform(unsigned int state[4], unsigned char block[64])
...{
    unsigned int a = state[0], b = state[1], c = state[2], d = state[3], x[16];
    MD5_Decode(x, block, 64);
    /**//* Round 1 */
    FF(a, b, c, d, x[0], S11, 0xd76aa478);    /**//* 1 */
    FF(d, a, b, c, x[1], S12, 0xe8c7b756);    /**//* 2 */
    FF(c, d, a, b, x[2], S13, 0x242070db);    /**//* 3 */
    FF(b, c, d, a, x[3], S14, 0xc1bdceee);    /**//* 4 */
    FF(a, b, c, d, x[4], S11, 0xf57c0faf);    /**//* 5 */
    FF(d, a, b, c, x[5], S12, 0x4787c62a);    /**//* 6 */
    FF(c, d, a, b, x[6], S13, 0xa8304613);    /**//* 7 */
    FF(b, c, d, a, x[7], S14, 0xfd469501);    /**//* 8 */
    FF(a, b, c, d, x[8], S11, 0x698098d8);    /**//* 9 */
    FF(d, a, b, c, x[9], S12, 0x8b44f7af);    /**//* 10 */
    FF(c, d, a, b, x[10], S13, 0xffff5bb1);   /**//* 11 */
    FF(b, c, d, a, x[11], S14, 0x895cd7be);   /**//* 12 */
    FF(a, b, c, d, x[12], S11, 0x6b901122);   /**//* 13 */
    FF(d, a, b, c, x[13], S12, 0xfd987193);   /**//* 14 */
    FF(c, d, a, b, x[14], S13, 0xa679438e);   /**//* 15 */
    FF(b, c, d, a, x[15], S14, 0x49b40821);   /**//* 16 */

    /**//* Round 2 */
    GG(a, b, c, d, x[1], S21, 0xf61e2562);    /**//* 17 */
    GG(d, a, b, c, x[6], S22, 0xc040b340);    /**//* 18 */
    GG(c, d, a, b, x[11], S23, 0x265e5a51);   /**//* 19 */
    GG(b, c, d, a, x[0], S24, 0xe9b6c7aa);    /**//* 20 */
    GG(a, b, c, d, x[5], S21, 0xd62f105d);    /**//* 21 */
    GG(d, a, b, c, x[10], S22, 0x2441453);    /**//* 22 */
    GG(c, d, a, b, x[15], S23, 0xd8a1e681);   /**//* 23 */
    GG(b, c, d, a, x[4], S24, 0xe7d3fbc8);    /**//* 24 */
    GG(a, b, c, d, x[9], S21, 0x21e1cde6);    /**//* 25 */
    GG(d, a, b, c, x[14], S22, 0xc33707d6);   /**//* 26 */
    GG(c, d, a, b, x[3], S23, 0xf4d50d87);    /**//* 27 */
    GG(b, c, d, a, x[8], S24, 0x455a14ed);    /**//* 28 */
    GG(a, b, c, d, x[13], S21, 0xa9e3e905);   /**//* 29 */
    GG(d, a, b, c, x[2], S22, 0xfcefa3f8);    /**//* 30 */
    GG(c, d, a, b, x[7], S23, 0x676f02d9);    /**//* 31 */
    GG(b, c, d, a, x[12], S24, 0x8d2a4c8a);   /**//* 32 */

    /**//* Round 3 */

    HH(a, b, c, d, x[5], S31, 0xfffa3942);    /**//* 33 */
    HH(d, a, b, c, x[8], S32, 0x8771f681);    /**//* 34 */
    HH(c, d, a, b, x[11], S33, 0x6d9d6122);   /**//* 35 */
    HH(b, c, d, a, x[14], S34, 0xfde5380c);   /**//* 36 */
    HH(a, b, c, d, x[1], S31, 0xa4beea44);    /**//* 37 */
    HH(d, a, b, c, x[4], S32, 0x4bdecfa9);    /**//* 38 */
    HH(c, d, a, b, x[7], S33, 0xf6bb4b60);    /**//* 39 */
    HH(b, c, d, a, x[10], S34, 0xbebfbc70);   /**//* 40 */
    HH(a, b, c, d, x[13], S31, 0x289b7ec6);   /**//* 41 */
    HH(d, a, b, c, x[0], S32, 0xeaa127fa);    /**//* 42 */
    HH(c, d, a, b, x[3], S33, 0xd4ef3085);    /**//* 43 */
    HH(b, c, d, a, x[6], S34, 0x4881d05); /**//* 44 */
    HH(a, b, c, d, x[9], S31, 0xd9d4d039);    /**//* 45 */
    HH(d, a, b, c, x[12], S32, 0xe6db99e5);   /**//* 46 */
    HH(c, d, a, b, x[15], S33, 0x1fa27cf8);   /**//* 47 */
    HH(b, c, d, a, x[2], S34, 0xc4ac5665);    /**//* 48 */

    /**//* Round 4 */
    II(a, b, c, d, x[0], S41, 0xf4292244);    /**//* 49 */
    II(d, a, b, c, x[7], S42, 0x432aff97);    /**//* 50 */
    II(c, d, a, b, x[14], S43, 0xab9423a7);   /**//* 51 */
    II(b, c, d, a, x[5], S44, 0xfc93a039);    /**//* 52 */
    II(a, b, c, d, x[12], S41, 0x655b59c3);   /**//* 53 */
    II(d, a, b, c, x[3], S42, 0x8f0ccc92);    /**//* 54 */
    II(c, d, a, b, x[10], S43, 0xffeff47d);   /**//* 55 */
    II(b, c, d, a, x[1], S44, 0x85845dd1);    /**//* 56 */
    II(a, b, c, d, x[8], S41, 0x6fa87e4f);    /**//* 57 */
    II(d, a, b, c, x[15], S42, 0xfe2ce6e0);   /**//* 58 */
    II(c, d, a, b, x[6], S43, 0xa3014314);    /**//* 59 */
    II(b, c, d, a, x[13], S44, 0x4e0811a1);   /**//* 60 */
    II(a, b, c, d, x[4], S41, 0xf7537e82);    /**//* 61 */
    II(d, a, b, c, x[11], S42, 0xbd3af235);   /**//* 62 */
    II(c, d, a, b, x[2], S43, 0x2ad7d2bb);    /**//* 63 */
    II(b, c, d, a, x[9], S44, 0xeb86d391);    /**//* 64 */

    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;

    memset((char *) x, 0, sizeof(x));
}

void MD5_Init(MD5Context * context)
...{
    context->count[0] = context->count[1] = 0;

    context->state[0] = 0x67452301;
    context->state[1] = 0xefcdab89;
    context->state[2] = 0x98badcfe;
    context->state[3] = 0x10325476;
}

void MD5_Update(MD5Context * context, unsigned char * buf, int len)
...{
    unsigned int i, index, partLen;
    index = (unsigned int) ((context->count[0] >> 3) & 0x3F);
    if ((context->count[0] += ((unsigned int) len << 3)) < ((unsigned int) len << 3))
        context->count[1]++;
    context->count[1] += ((unsigned int) len >> 29);

    partLen = 64 - index;

    if (len >= partLen) 
    ...{
        memcpy((char *) &context->buffer[index], (char *) buf, partLen);
        MD5_Transform(context->state, context->buffer);

        for (i = partLen; i + 63 < len; i += 64)
            MD5_Transform(context->state, &buf[i]);
        index = 0;
    }
    else 
    ...{
        i = 0;
    }
    memcpy((char *) &context->buffer[index], (char *) &buf[i], len - i);
}

void MD5_Final(MD5Context * context, unsigned char digest[16])
...{
    unsigned char bits[8];
    unsigned int index, padLen;
    MD5_Encode(bits, context->count, 8);
    index = (unsigned int) ((context->count[0] >> 3) & 0x3f);
    padLen = (index < 56) ? (56 - index) : (120 - index);
    MD5_Update(context, PADDING, padLen);
    MD5_Update(context, bits, 8);
    MD5_Encode(digest, context->state, 16);
    memset((char *) context, 0, sizeof(*context));
}

// 计算文件的 MD5
// filename 文件名, 计算的 MD5 放入缓冲区 buff 中
// buff 长度为16 字节
bool MD5_File ( const char * filename,unsigned char *buff )
...{
    FILE *file;
    MD5Context context;
//    unsigned char buff[16];
    int i,len;
    unsigned char buffer[0x0400];

    if (!(file = fopen (filename, "rb")))
    ...{
        printf ("%s can't be opened ", filename);
        return false;
    }
    else 
    ...{
        MD5_Init (&context);
        while (len = fread (buffer, 1, 1024, file))
            MD5_Update (&context, buffer, len);
        MD5_Final(&context,buff);
        fclose (file);
        for(i=0;i<16;i++)
        ...{
            printf("%x",(buff[i] & 0xF0)>>4);
            printf("%x",buff[i] & 0x0F);
        }
        printf(" ");
        return true;
    }
}

bool MD5_File ( const char * filename,std::string& md5str )
...{
    FILE *file;
    MD5Context context;
    unsigned char buff[16];
    int i,len;
    unsigned char buffer[0x0400];
    
    char md5char[16]=...{'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'};

    if (!(file = fopen (filename, "rb")))
    ...{
        printf ("%s can't be opened ", filename);
        return false;
    }
    else 
    ...{
        MD5_Init (&context);
        while (len = fread (buffer, 1, 1024, file))
            MD5_Update (&context, buffer, len);
        MD5_Final(&context,buff);
        fclose (file);
        for(i=0;i<16;i++)
        ...{
            md5str += md5char[(buff[i] & 0xF0)>>4];
            md5str += md5char[buff[i] & 0x0F];
        }
        return true;
    }
}

测试：

 

      int i =0,j,len,startTime,endTime;

        MD5Context context;

        unsigned char buff[16];


        char str[7][100] = 
        ...{

            "",

                "a",

                "abc",

                "message digest",

                "abcdefghijklmnopqrstuvwxyz",

                "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789",

                "12345678901234567890123456789012345678901234567890123456789012345678901234567890"

        };

        for(i=0;i<6;i++)

        ...{

            len = strlen(str[i]);

            MD5_Init(&context);

            MD5_Update(&context,(unsigned char *)str[i], len);

            MD5_Final(&context,buff);

            printf("MD5("%s") =  ",str[i]);

            for(j=0;j<16;j++)

            ...{

                printf("%x",(buff[j] & 0xF0)>>4);

                printf("%x",buff[j] & 0x0F);

            }

            printf(" *********************************************************** ");

        }

        printf("Wating... ");
        std::string md5str;
        MD5_File("tiger_c.jpg",md5str );
        std::cout<<"::::::::::::::"<<md5str<<" ";
        return 0;

MD5("") =
d41d8cd98f00b204e9800998ecf8427e
***********************************************************
MD5("a") =
0cc175b9c0f1b6a831c399e269772661
***********************************************************
MD5("abc") =
900150983cd24fb0d6963f7d28e17f72
***********************************************************
MD5("message digest") =
f96b697d7cb7938d525a2f31aaf161d0
***********************************************************
MD5("abcdefghijklmnopqrstuvwxyz") =
c3fcd3d76192e4007dfb496cca67e13b
***********************************************************
MD5("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789") =
d174ab98d277d9f5a5611c2c9f419d9f
***********************************************************
Wating...
::::::::::::::41fd801b9ae124d8b69de40c0961c615

 

转载自： http://blog.csdn.net/kofsky/article/details/2128611