MD5的实现

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闲着没事干，索性实现一下MD5

具体的东西，说白了，就是把原始数据+补充数据共分割成N个64位的小段，每个小段又分成16个小节，然后每个小段参与一次四轮运算，用ABCD这四个数关联起他们，保证数据有丝毫变动，得到的MD5码，会完全变动。

F=(x&y)|((~x)&z)

G=(x&z)|(y&(~z))

H=x^y^z

I=y^(x|(~z))

FF(a,b,c,d,Mj,s,ti)表示a=b+((a+F(b,c,d)+Mj+ti)<<<s)
GG(a,b,c,d,Mj,s,ti)表示a=b+((a+G(b,c,d)+Mj+ti)<<<s)
HH(a,b,c,d,Mj,s,ti)表示a=b+((a+H(b,c,d)+Mj+ti)<<<s)
II(a,b,c,d,Mj,s,ti)表示a=b+((a+I(b,c,d)+Mj+ti)<<<s)

unsigned int A=0x67452301UL;
unsigned int B=0xEFCDAB89UL;
unsigned int C=0x98BADCFEUL;
unsigned int D=0x10325476UL;

四轮循环N次，每i次取第i个分割里的m[16]参与运算，最后得到ABCD四个值，A占4个字节，记为A1A2A3A4

最后按A4A3A2A1B4B3B2B1C4C3C2C1D4D3D2D1取16进制输出即得到md5码

//四轮循环

{

a=A;

b=B;

c=C

d=D;

FF(a,b,c,d,m[0],7,0xd76aa478);//a,b,c,d不用解释，m[0]是每个分割出来的64字节段的其中32位的一块，7任意数，0xd76aa478是(2^32)*abs()
FF(d,a,b,c,m[1],12,0xe8c7b756);
FF(c,d,a,b,m[2],17,0x242070db);
FF(b,c,d,a,m[3],22,0xc1bdceee);
FF(a,b,c,d,m4],7,0xf57c0faf);
FF(d,a,b,c,m[5],12,0x4787c62a);
FF(c,d,a,b,m[6],17,0xa8304613);
FF(b,c,d,a,m[7],22,0xfd469501) ;
FF(a,b,c,d,m[8],7,0x698098d8) ;
FF(d,a,b,c,m[9],12,0x8b44f7af) ;
FF(c,d,a,b,m[10],17,0xffff5bb1) ;
FF(b,c,d,a,m[11],22,0x895cd7be) ;
FF(a,b,c,d,m[12],7,0x6b901122) ;
FF(d,a,b,c,m[13],12,0xfd987193) ;
FF(c,d,a,b,m[14],17,0xa679438e) ;
FF(b,c,d,a,m[15],22,0x49b40821);

GG(a,b,c,d,m[1],5,0xf61e2562);
GG(d,a,b,c,m[6],9,0xc040b340);
GG(c,d,a,b,m[11],14,0x265e5a51);
GG(b,c,d,a,m[0],20,0xe9b6c7aa) ;
GG(a,b,c,d,m[5],5,0xd62f105d) ;
GG(d,a,b,c,m[10],9,0x02441453) ;
GG(c,d,a,b,m[15],14,0xd8a1e681);
GG(b,c,d,a,m[4],20,0xe7d3fbc8) ;
GG(a,b,c,d,m[9],5,0x21e1cde6) ;
GG(d,a,b,c,m[14],9,0xc33707d6) ;
GG(c,d,a,b,m[3],14,0xf4d50d87) ;
GG(b,c,d,a,m[8],20,0x455a14ed);
GG(a,b,c,d,m[13],5,0xa9e3e905);
GG(d,a,b,c,m[2],9,0xfcefa3f8) ;
GG(c,d,a,b,m[7],14,0x676f02d9) ;
GG(b,c,d,a,m[12],20,0x8d2a4c8a);

HH(a,b,c,d,m[5],4,0xfffa3942);
HH(d,a,b,c,m[8],11,0x8771f681);
HH(c,d,a,b,m[11],16,0x6d9d6122);
HH(b,c,d,a,m[14],23,0xfde5380c) ;
HH(a,b,c,d,m[1],4,0xa4beea44) ;
HH(d,a,b,c,m[4],11,0x4bdecfa9) ;
HH(c,d,a,b,m[7],16,0xf6bb4b60) ;
HH(b,c,d,a,m[10],23,0xbebfbc70);
HH(a,b,c,d,m[13],4,0x289b7ec6);
HH(d,a,b,c,m[0],11,0xeaa127fa);
HH(c,d,a,b,m[3],16,0xd4ef3085);
HH(b,c,d,a,m[6],23,0x04881d05);
HH(a,b,c,d,m[9],4,0xd9d4d039);
HH(d,a,b,c,m[12],11,0xe6db99e5);
HH(c,d,a,b,m[15],16,0x1fa27cf8) ;
HH(b,c,d,a,m[2],23,0xc4ac5665);

II(a,b,c,d,m[0],6,0xf4292244) ;
II(d,a,b,c,m[7],10,0x432aff97) ;
II(c,d,a,b,m[14],15,0xab9423a7);
II(b,c,d,a,m[5],21,0xfc93a039) ;
II(a,b,c,d,m[12],6,0x655b59c3) ;
II(d,a,b,c,m[3],10,0x8f0ccc92) ;
II(c,d,a,b,m[10],15,0xffeff47d);
II(b,c,d,a,m[1],21,0x85845dd1) ;
II(a,b,c,d,m[8],6,0x6fa87e4f) ;
II(d,a,b,c,m[15],10,0xfe2ce6e0);
II(c,d,a,b,m[6],15,0xa3014314) ;
II(b,c,d,a,m[13],21,0x4e0811a1);
II(a,b,c,d,m[4],6,0xf7537e82) ;
II(d,a,b,c,m[11],10,0xbd3af235);
II(c,d,a,b,m[2],15,0x2ad7d2bb);
II(b,c,d,a,m[9],21,0xeb86d391);

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

}

附上代码。代码还有很多问题。但是懒得改了，。。凑合看吧

typedef unsigned int uint;class MD5{    public:    MD5(char *str=NULL);    unsigned char* GET(){return MD;}    void PUT();    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));}    uint FF(uint &a,uint &b,uint &c,uint &d,uint m,int ss,uint tt);    uint GG(uint &a,uint &b,uint &c,uint &d,uint m,int ss,uint tt);    uint HH(uint &a,uint &b,uint &c,uint &d,uint m,int ss,uint tt);    uint II(uint &a,uint &b,uint &c,uint &d,uint m,int ss,uint tt);    uint mov(uint x,int ss){};    private:    int N,M;    static uint t[64];//值为4294967295*abs(sin(i))的整数部分    static int s[16];//循环左移s    uint **p;    uint A,B,C,D;    uint a,b,c,d;    unsigned char MD[16];};//  FF(a,b,c,d,Mj,s,ti)表示a=b+((a+F(b,c,d)+Mj+ti)<<<s)//  GG(a,b,c,d,Mj,s,ti)表示a=b+((a+G(b,c,d)+Mj+ti)<<<s)//  HH(a,b,c,d,Mj,s,ti)表示a=b+((a+H(b,c,d)+Mj+ti)<<<s)//  II(a,b,c,d,Mj,s,ti)表示a=b+((a+I(b,c,d)+Mj+ti)<<<s)void MD5::PUT(){    for(int i=0;i<16;i++)        printf("%x",MD[i]);    cout<<endl;}uint MD5::FF(uint &a,uint &b,uint &c,uint &d,uint m,int ss,uint tt){    uint mid,qut;    mid=a+F(b,c,d)+m+tt;    qut=mid;    mid>>=(32-tt);    qut<<=tt;    qut^=mid;    a=b+qut;    return a;}uint MD5::GG(uint &a,uint &b,uint &c,uint &d,uint m,int ss,uint tt){    uint mid,qut;    mid=a+F(b,c,d)+m+tt;    qut=mid;    mid>>=(32-tt);    qut<<=tt;    qut^=mid;    a=b+qut;    return a;}uint MD5::HH(uint &a,uint &b,uint &c,uint &d,uint m,int ss,uint tt){    uint mid,qut;    mid=a+F(b,c,d)+m+tt;    qut=mid;    mid>>=(32-tt);    qut<<=tt;    qut^=mid;    a=b+qut;    return a;}uint MD5::II(uint &a,uint &b,uint &c,uint &d,uint m,int ss,uint tt){    uint mid,qut;    mid=a+F(b,c,d)+m+tt;    qut=mid;    mid>>=(32-tt);    qut<<=tt;    qut^=mid;    a=b+qut;    return a;}MD5::MD5(char *str){    A=0x67452301UL;    B=0xEFCDAB89UL;    C=0x98BADCFEUL;    D=0x10325476UL;    int m=strlen(str),z=0;    N=m/64+1;    M=m%64;    /*-----------------分配内存-----------------*/    p=new  uint*[N];    for(int i=0;i<N;i++)        p[i]=new uint[16];    for(int i=0;i<N;i++)        for(int j=0;j<16;j++)            p[i][j]=0;    /*-----------------构造分组---------------*/    for(int i=0;i<N;i++)    {        for(int j=0;j<64;j++)        {             if(z==m)            {                p[i][j/4]<<=8;                p[i][j/4]^=128;                for(;j<64;j++)                    p[i][j/4]<<=8;                break;            }            p[i][j/4]<<=8;            p[i][j/4]^=str[z++];        }    }    /*------------------四轮运算-------------------*/    for(int i=0;i<N;i++)    {        a=A;        b=B;        c=C;        d=D;        for(int j=0;j<16;j++)        {            FF(a,b,c,d,p[i][j],s[i],t[16*i+j]);            uint o=a;            a=b;            b=c;            c=d;            d=o;        }        for(int j=0;j<16;j++)        {            GG(a,b,c,d,p[i][j],s[i],t[16*i+j]);            uint o=a;            a=b;            b=c;            c=d;            d=o;        }        for(int j=0;j<16;j++)        {            HH(a,b,c,d,p[i][j],s[i],t[16*i+j]);            uint o=a;            a=b;            b=c;            c=d;            d=o;        }        for(int j=0;j<16;j++)        {            II(a,b,c,d,p[i][j],s[i],t[16*i+j]);            uint o=a;            a=b;            b=c;            c=d;            d=o;        }        A+=a;        B+=b;        C+=c;        D+=d;//        cout<<"A="<<A<<endl;//        cout<<"B="<<B<<endl;//        cout<<"C="<<C<<endl;//        cout<<"D="<<D<<endl;    }    /*---------------四轮运算完成--------------*/    /*---------------构造MD5输出码----------------*/    int i;    for(i=0;i<4;i++)    {        MD[i]=MD[i+4]=MD[i+8]=MD[i+12]=0;        MD[i]=MD[i]^(A>>(i*8));        MD[i+4]=MD[i+4]^(B>>(i*8));        MD[i+8]=MD[i+8]^(C>>(i*8));        MD[i+12]=MD[i+12]^(D>>(i*8));    }//    cout<<"A="<<A<<endl;//    cout<<"B="<<B<<endl;//    cout<<"C="<<C<<endl;//    cout<<"D="<<D<<endl;}uint  MD5::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};int MD5::s[16]={7,12,17,22,5,9,14,20,4,11,16,32,6,10,15,21};

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