MD5的实现

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1.问题描述

    MD5512比特一块的方式处理输入的消息文本,每个块又划分为十六个32比特的子块。算法的输出由四个32比特的块组成,将它们级联成一个128比特的Hash值。

①首先填充消息使填充后的长度恰好为一个比512的倍数小64的数。填充方法是附一个“1”在消息后面,再补多个“0”。然后,在其后附上64比特的消息长度(填充前)的二进制表示。算法中使用了四个32比特的变量ABCD,先把这四个变量初始化为:

A=01234567B=89ABCDEFC=FEDCBA98D=76543210

称它们为链接变量。

     接着进行算法的主循环,循环的次数是消息中512比特的块的数目。

将上面四个变量复制到另外的变量中:AAABBBCCCDDD

主循环有四轮, 每一轮由16次操作组成。FGHI函数,FFGGHHII四种操作详见教材P116-P118。所有这些步骤进行完之后,将ABCD分别加上AABBCCDD,然后用下一块数据继续进行算法。

③最后的输出是ABCD的级联。

2.基本要求

   MD5(x)的形式实现,x01串。

3. 实现提示

注意消息文本、各种变量的类型及其类型转换。

第一种:

#include<stdio.h>
#include<string.h>
#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 RL(x, y) (((x) << (y)) | ((x) >> (32 - (y))))  //x向左循环移y位

#define PP(x) (x<<24)|((x<<8)&0xff0000)|((x>>8)&0xff00)|(x>>24)  //将x高低位互换,例如PP(aabbccdd)=ddccbbaa

#define FF(a, b, c, d, x, s, ac) a = b + (RL((a + F(b,c,d) + x + ac),s))
#define GG(a, b, c, d, x, s, ac) a = b + (RL((a + G(b,c,d) + x + ac),s))
#define HH(a, b, c, d, x, s, ac) a = b + (RL((a + H(b,c,d) + x + ac),s))
#define II(a, b, c, d, x, s, ac) a = b + (RL((a + I(b,c,d) + x + ac),s))

unsigned A,B,C,D,a,b,c,d,i,len,flen[2],x[16];   //i临时变量,len文件长,flen[2]为64位二进制表示的文件初始长度
char filename[200];   //文件名
FILE *fp;

void md5(){                 //MD5核心算法,供64轮

  a=A,b=B,c=C,d=D;
  /**//* Round 1 */
  FF (a, b, c, d, x[ 0],  7, 0xd76aa478); /**//* 1 */
  FF (d, a, b, c, x[ 1], 12, 0xe8c7b756); /**//* 2 */
  FF (c, d, a, b, x[ 2], 17, 0x242070db); /**//* 3 */
  FF (b, c, d, a, x[ 3], 22, 0xc1bdceee); /**//* 4 */
  FF (a, b, c, d, x[ 4],  7, 0xf57c0faf); /**//* 5 */
  FF (d, a, b, c, x[ 5], 12, 0x4787c62a); /**//* 6 */
  FF (c, d, a, b, x[ 6], 17, 0xa8304613); /**//* 7 */
  FF (b, c, d, a, x[ 7], 22, 0xfd469501); /**//* 8 */
  FF (a, b, c, d, x[ 8],  7, 0x698098d8); /**//* 9 */
  FF (d, a, b, c, x[ 9], 12, 0x8b44f7af); /**//* 10 */
  FF (c, d, a, b, x[10], 17, 0xffff5bb1); /**//* 11 */
  FF (b, c, d, a, x[11], 22, 0x895cd7be); /**//* 12 */
  FF (a, b, c, d, x[12],  7, 0x6b901122); /**//* 13 */
  FF (d, a, b, c, x[13], 12, 0xfd987193); /**//* 14 */
  FF (c, d, a, b, x[14], 17, 0xa679438e); /**//* 15 */
  FF (b, c, d, a, x[15], 22, 0x49b40821); /**//* 16 */

 /**//* Round 2 */
  GG (a, b, c, d, x[ 1],  5, 0xf61e2562); /**//* 17 */
  GG (d, a, b, c, x[ 6],  9, 0xc040b340); /**//* 18 */
  GG (c, d, a, b, x[11], 14, 0x265e5a51); /**//* 19 */
  GG (b, c, d, a, x[ 0], 20, 0xe9b6c7aa); /**//* 20 */
  GG (a, b, c, d, x[ 5],  5, 0xd62f105d); /**//* 21 */
  GG (d, a, b, c, x[10],  9, 0x02441453); /**//* 22 */
  GG (c, d, a, b, x[15], 14, 0xd8a1e681); /**//* 23 */
  GG (b, c, d, a, x[ 4], 20, 0xe7d3fbc8); /**//* 24 */
  GG (a, b, c, d, x[ 9],  5, 0x21e1cde6); /**//* 25 */
  GG (d, a, b, c, x[14],  9, 0xc33707d6); /**//* 26 */
  GG (c, d, a, b, x[ 3], 14, 0xf4d50d87); /**//* 27 */
  GG (b, c, d, a, x[ 8], 20, 0x455a14ed); /**//* 28 */
  GG (a, b, c, d, x[13],  5, 0xa9e3e905); /**//* 29 */
  GG (d, a, b, c, x[ 2],  9, 0xfcefa3f8); /**//* 30 */
  GG (c, d, a, b, x[ 7], 14, 0x676f02d9); /**//* 31 */
  GG (b, c, d, a, x[12], 20, 0x8d2a4c8a); /**//* 32 */

  /**//* Round 3 */
  HH (a, b, c, d, x[ 5],  4, 0xfffa3942); /**//* 33 */
  HH (d, a, b, c, x[ 8], 11, 0x8771f681); /**//* 34 */
  HH (c, d, a, b, x[11], 16, 0x6d9d6122); /**//* 35 */
  HH (b, c, d, a, x[14], 23, 0xfde5380c); /**//* 36 */
  HH (a, b, c, d, x[ 1],  4, 0xa4beea44); /**//* 37 */
  HH (d, a, b, c, x[ 4], 11, 0x4bdecfa9); /**//* 38 */
  HH (c, d, a, b, x[ 7], 16, 0xf6bb4b60); /**//* 39 */
  HH (b, c, d, a, x[10], 23, 0xbebfbc70); /**//* 40 */
  HH (a, b, c, d, x[13],  4, 0x289b7ec6); /**//* 41 */
  HH (d, a, b, c, x[ 0], 11, 0xeaa127fa); /**//* 42 */
  HH (c, d, a, b, x[ 3], 16, 0xd4ef3085); /**//* 43 */
  HH (b, c, d, a, x[ 6], 23, 0x04881d05); /**//* 44 */
  HH (a, b, c, d, x[ 9],  4, 0xd9d4d039); /**//* 45 */
  HH (d, a, b, c, x[12], 11, 0xe6db99e5); /**//* 46 */
  HH (c, d, a, b, x[15], 16, 0x1fa27cf8); /**//* 47 */
  HH (b, c, d, a, x[ 2], 23, 0xc4ac5665); /**//* 48 */

  /**//* Round 4 */
  II (a, b, c, d, x[ 0],  6, 0xf4292244); /**//* 49 */
  II (d, a, b, c, x[ 7], 10, 0x432aff97); /**//* 50 */
  II (c, d, a, b, x[14], 15, 0xab9423a7); /**//* 51 */
  II (b, c, d, a, x[ 5], 21, 0xfc93a039); /**//* 52 */
  II (a, b, c, d, x[12],  6, 0x655b59c3); /**//* 53 */
  II (d, a, b, c, x[ 3], 10, 0x8f0ccc92); /**//* 54 */
  II (c, d, a, b, x[10], 15, 0xffeff47d); /**//* 55 */
  II (b, c, d, a, x[ 1], 21, 0x85845dd1); /**//* 56 */
  II (a, b, c, d, x[ 8],  6, 0x6fa87e4f); /**//* 57 */
  II (d, a, b, c, x[15], 10, 0xfe2ce6e0); /**//* 58 */
  II (c, d, a, b, x[ 6], 15, 0xa3014314); /**//* 59 */
  II (b, c, d, a, x[13], 21, 0x4e0811a1); /**//* 60 */
  II (a, b, c, d, x[ 4],  6, 0xf7537e82); /**//* 61 */
  II (d, a, b, c, x[11], 10, 0xbd3af235); /**//* 62 */
  II (c, d, a, b, x[ 2], 15, 0x2ad7d2bb); /**//* 63 */
  II (b, c, d, a, x[ 9], 21, 0xeb86d391); /**//* 64 */

  A += a;
  B += b;
  C += c;
  D += d;

}

main(){
  while(1){
    printf("Input file:");
    gets(filename);    //用get函数,避免scanf以空格分割数据,
    if (filename[0]==34) filename[strlen(filename)-1]=0,strcpy(filename,filename+1);  //支持文件拖曳,但会多出双引号,这里是处理多余的双引号
    if (!strcmp(filename,"exit")) return;  //输入exit退出
    if (!(fp=fopen(filename,"rb"))) {printf("Can not open this file!/n");continue;}  //以二进制打开文件
    fseek(fp, 0, SEEK_END);  //文件指针转到文件末尾
    if((len=ftell(fp))==-1) {printf("Sorry! Can not calculate files which larger than 2 GB!/n");fclose(fp);continue;}  //ftell函数返回long,最大为2GB,超出返回-1
    rewind(fp);  //文件指针复位到文件头
    A=0x67452301,B=0xefcdab89,C=0x98badcfe,D=0x10325476; //初始化链接变量
    flen[1]=len/0x20000000;     //flen单位是bit
    flen[0]=(len%0x20000000)*8;
    memset(x,0,64);   //初始化x数组为0
    fread(&x,4,16,fp);  //以4字节为一组,读取16组数据
    for(i=0;i<len/64;i++){    //循环运算直至文件结束
      md5();
      memset(x,0,64);
      fread(&x,4,16,fp);
    }
    ((char*)x)[len%64]=128;  //文件结束补1,补0操作,128二进制即10000000
    if(len%64>55) md5(),memset(x,0,64);
    memcpy(x+14,flen,8);    //文件末尾加入原文件的bit长度
    md5();
    fclose(fp);
    printf("MD5 Code:%08x%08x%08x%08x/n",PP(A),PP(B),PP(C),PP(D));  //高低位逆反输出
  }
}

 

第二种:

#include <stdio.h>
#include <memory.h>
#include<windows.h>

#define DWORD unsigned int
#define BYTE unsigned char


#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) + (DWORD)(ac); (a) = ROTATE_LEFT ((a), (s)); (a) += (b); }
#define GG(a, b, c, d, x, s, ac) { (a) += G ((b), (c), (d)) + (x) + (DWORD)(ac); (a) = ROTATE_LEFT ((a), (s)); (a) += (b); }
#define HH(a, b, c, d, x, s, ac) { (a) += H ((b), (c), (d)) + (x) + (DWORD)(ac); (a) = ROTATE_LEFT ((a), (s)); (a) += (b); }
#define II(a, b, c, d, x, s, ac) { (a) += I ((b), (c), (d)) + (x) + (DWORD)(ac); (a) = ROTATE_LEFT ((a), (s)); (a) += (b); }

typedef struct{
    DWORD State[4];
    DWORD Count[2];
    BYTE Buffer[64];
} MD5_CTX;

class MD5{
private:
    int S[4][4];
    BYTE PADDING[64];
    MD5_CTX Context;
    char Result[33];

    void Encode(BYTE *Output, DWORD *Input, unsigned int Len)
    {
        unsigned int i, j;
        for(i = 0, j = 0; j < Len; i++, j += 4)
        {
            Output[j] = (BYTE)(Input[i] & 0xff);
            Output[j+1] = (BYTE)((Input[i] >> 8) & 0xff);
            Output[j+2] = (BYTE)((Input[i] >> 16) & 0xff);
            Output[j+3] = (BYTE)((Input[i] >> 24) & 0xff);
        }
    }
    void Decode(DWORD *Output, BYTE *Input, unsigned int Len)
    {
        unsigned int i, j;
        for(i = 0, j = 0; j < Len; i++, j += 4) Output[i] = ((DWORD)Input[j]) | (((DWORD)Input[j+1]) << 8) | (((DWORD)Input[j+2]) << 16) | (((DWORD)Input[j+3]) << 24);
    }
    void Transform(BYTE *Block)
    {
        DWORD a = Context.State[0];
        DWORD b = Context.State[1];
        DWORD c = Context.State[2];
        DWORD d = Context.State[3];
       
        DWORD x[16];
   
        Decode(x, Block, 64);

        FF (a, b, c, d, x[ 0], S[0][0], 0xd76aa478);
        FF (d, a, b, c, x[ 1], S[0][1], 0xe8c7b756);
        FF (c, d, a, b, x[ 2], S[0][2], 0x242070db);
        FF (b, c, d, a, x[ 3], S[0][3], 0xc1bdceee);
        FF (a, b, c, d, x[ 4], S[0][0], 0xf57c0faf);
        FF (d, a, b, c, x[ 5], S[0][1], 0x4787c62a);
        FF (c, d, a, b, x[ 6], S[0][2], 0xa8304613);
        FF (b, c, d, a, x[ 7], S[0][3], 0xfd469501);
        FF (a, b, c, d, x[ 8], S[0][0], 0x698098d8);
        FF (d, a, b, c, x[ 9], S[0][1], 0x8b44f7af);
        FF (c, d, a, b, x[10], S[0][2], 0xffff5bb1);
        FF (b, c, d, a, x[11], S[0][3], 0x895cd7be);
        FF (a, b, c, d, x[12], S[0][0], 0x6b901122);
        FF (d, a, b, c, x[13], S[0][1], 0xfd987193);
        FF (c, d, a, b, x[14], S[0][2], 0xa679438e);
        FF (b, c, d, a, x[15], S[0][3], 0x49b40821);

        GG (a, b, c, d, x[ 1], S[1][0], 0xf61e2562);
        GG (d, a, b, c, x[ 6], S[1][1], 0xc040b340);
        GG (c, d, a, b, x[11], S[1][2], 0x265e5a51);
        GG (b, c, d, a, x[ 0], S[1][3], 0xe9b6c7aa);
        GG (a, b, c, d, x[ 5], S[1][0], 0xd62f105d);
        GG (d, a, b, c, x[10], S[1][1],  0x2441453);
        GG (c, d, a, b, x[15], S[1][2], 0xd8a1e681);
        GG (b, c, d, a, x[ 4], S[1][3], 0xe7d3fbc8);
        GG (a, b, c, d, x[ 9], S[1][0], 0x21e1cde6);
        GG (d, a, b, c, x[14], S[1][1], 0xc33707d6);
        GG (c, d, a, b, x[ 3], S[1][2], 0xf4d50d87);
        GG (b, c, d, a, x[ 8], S[1][3], 0x455a14ed);
        GG (a, b, c, d, x[13], S[1][0], 0xa9e3e905);
        GG (d, a, b, c, x[ 2], S[1][1], 0xfcefa3f8);
        GG (c, d, a, b, x[ 7], S[1][2], 0x676f02d9);
        GG (b, c, d, a, x[12], S[1][3], 0x8d2a4c8a);

        HH (a, b, c, d, x[ 5], S[2][0], 0xfffa3942);
        HH (d, a, b, c, x[ 8], S[2][1], 0x8771f681);
        HH (c, d, a, b, x[11], S[2][2], 0x6d9d6122);
        HH (b, c, d, a, x[14], S[2][3], 0xfde5380c);
        HH (a, b, c, d, x[ 1], S[2][0], 0xa4beea44);
        HH (d, a, b, c, x[ 4], S[2][1], 0x4bdecfa9);
        HH (c, d, a, b, x[ 7], S[2][2], 0xf6bb4b60);
        HH (b, c, d, a, x[10], S[2][3], 0xbebfbc70);
        HH (a, b, c, d, x[13], S[2][0], 0x289b7ec6);
        HH (d, a, b, c, x[ 0], S[2][1], 0xeaa127fa);
        HH (c, d, a, b, x[ 3], S[2][2], 0xd4ef3085);
        HH (b, c, d, a, x[ 6], S[2][3],  0x4881d05);
        HH (a, b, c, d, x[ 9], S[2][0], 0xd9d4d039);
        HH (d, a, b, c, x[12], S[2][1], 0xe6db99e5);
        HH (c, d, a, b, x[15], S[2][2], 0x1fa27cf8);
        HH (b, c, d, a, x[ 2], S[2][3], 0xc4ac5665);

        II (a, b, c, d, x[ 0], S[3][0], 0xf4292244);
        II (d, a, b, c, x[ 7], S[3][1], 0x432aff97);
        II (c, d, a, b, x[14], S[3][2], 0xab9423a7);
        II (b, c, d, a, x[ 5], S[3][3], 0xfc93a039);
        II (a, b, c, d, x[12], S[3][0], 0x655b59c3);
        II (d, a, b, c, x[ 3], S[3][1], 0x8f0ccc92);
        II (c, d, a, b, x[10], S[3][2], 0xffeff47d);
        II (b, c, d, a, x[ 1], S[3][3], 0x85845dd1);
        II (a, b, c, d, x[ 8], S[3][0], 0x6fa87e4f);
        II (d, a, b, c, x[15], S[3][1], 0xfe2ce6e0);
        II (c, d, a, b, x[ 6], S[3][2], 0xa3014314);
        II (b, c, d, a, x[13], S[3][3], 0x4e0811a1);
        II (a, b, c, d, x[ 4], S[3][0], 0xf7537e82);
        II (d, a, b, c, x[11], S[3][1], 0xbd3af235);
        II (c, d, a, b, x[ 2], S[3][2], 0x2ad7d2bb);
        II (b, c, d, a, x[ 9], S[3][3], 0xeb86d391);

        Context.State[0] += a;
        Context.State[1] += b;
        Context.State[2] += c;
        Context.State[3] += d;

        memset(x, 0, sizeof(x));
    }
    void Update(BYTE *Input, unsigned int InputLen)
    {   
        unsigned int i, Index, PartLen;

        Index = (unsigned int)((Context.Count[0] >> 3) & 0x3F);
   
        if((Context.Count[0] += ((DWORD)InputLen << 3)) < ((DWORD)InputLen << 3))
        {
            Context.Count[1]++;
        }
        Context.Count[1] += ((DWORD)InputLen >> 29);
   
        PartLen = 64 - Index;
   
        if(InputLen >= PartLen)
        {
            memcpy(&(Context.Buffer[Index]), Input, PartLen);
            Transform(Context.Buffer);
            for(i = PartLen; i + 63 < InputLen; i += 64)
            {
                Transform(&Input[i]);
            }
            Index = 0;
        }
        else
        {
            i = 0;
        }

        memcpy(&(Context.Buffer[Index]), &(Input[i]), InputLen-i);
    }
    void Final(BYTE *Digest)
    {
        BYTE Bits[8];
        unsigned int Index, PadLen;
   
        Encode(Bits, Context.Count, 8);
   
        Index = (unsigned int)((Context.Count[0] >> 3) & 0x3f);
        PadLen = (Index < 56) ? (56 - Index) : (120 - Index);
        Update(PADDING, PadLen);

        Update(Bits, 8);
   
        Encode(Digest, Context.State, 16);

        memset(&Context, 0, sizeof(Context));
    }
public:
    MD5()
    {
        memset(&Context, 0, sizeof(Context));

        S[0][0] = 7;  S[0][1] = 12; S[0][2] = 17; S[0][3] = 22;
        S[1][0] = 5;  S[1][1] = 9;  S[1][2] = 14; S[1][3] = 20;
        S[2][0] = 4;  S[2][1] = 11; S[2][2] = 16; S[2][3] = 23;
        S[3][0] = 6;  S[3][1] = 10; S[3][2] = 15; S[3][3] = 21;

        PADDING[0] = 0x80;
        for(int i = 1; i <= 63; ++i){ PADDING[i] = 0x00; }

        Context.Count[0] = Context.Count[1] = 0;
        Context.State[0] = 0x67452301;
        Context.State[1] = 0xefcdab89;
        Context.State[2] = 0x98badcfe;
        Context.State[3] = 0x10325476;
    }
    char *GetMD5HASH(char *C)
    {
        Update((BYTE *)(C), strlen(C));

        BYTE Digest[16];
        Final(Digest);

        for(int i = 0; i < 16; i++)
        {
            sprintf(Result+2*i, "%02X", Digest[i]);
        }
        Result[32] = 0;
        return Result;
    }
    void Restart()
    {
        memset(&Context, 0, sizeof(Context));

        S[0][0] = 7;  S[0][1] = 12; S[0][2] = 17; S[0][3] = 22;
        S[1][0] = 5;  S[1][1] = 9;  S[1][2] = 14; S[1][3] = 20;
        S[2][0] = 4;  S[2][1] = 11; S[2][2] = 16; S[2][3] = 23;
        S[3][0] = 6;  S[3][1] = 10; S[3][2] = 15; S[3][3] = 21;

        PADDING[0] = 0x80;
        for(int i = 1; i <= 63; ++i){ PADDING[i] = 0x00; }

        Context.Count[0] = Context.Count[1] = 0;
        Context.State[0] = 0x67452301;
        Context.State[1] = 0xefcdab89;
        Context.State[2] = 0x98badcfe;
        Context.State[3] = 0x10325476;

        memset(Result, 0, 33);
    }
};


int main(int argc, char *argv[])
{
    char s1[] = "abcdefghijklmnopqrstuvwxyz";
    MD5 obj;
    printf("%s",obj.GetMD5HASH(s1));
        return 0;
}

 
 
说明一下:这些都是借来的……版权不归我所有!呵呵!