DES算法

函数入口参数

void DES(ElemType StrText[64],ElemType KeyText[64],ElemType Mode)

　　StrText为需要处理的二进制串,KeyText为密钥二进制串,Mode为工作模式(1为加密,0为解密)

算法流程

　　1.将要处理的二进制串进行IP置换

　　2.将密钥进行PC1置换(64位转为56位),

　　3.进行16轮操作,对于第i轮操作:

　　　　1)将上一次得到的PC1密钥(级除去第一次外,其他的都经过移位处理)的结果左右部分(各28位)分别循环左移1位或2位,然后将移位后的密钥进行PC2[i]置换.

　　　　2)将处理串均等分为左右两串Li,Ri(各32位),然后将右串Ri通过E盒拓展为新的右串R'(48位),R'与上一步得到的PC2[i]子密钥进行异或操作,结果通过S盒输出(48为转为32位),然后通过P盒直接置换,再与Li异或.

　　　　3)将Ri赋给作出Li,R'赋值给Ri.

　　　　4)合并处理串StrText=Li+Ri.

　　4.将最新的处理串进行IP_1置换,置换结果即为所求的加密串或解密串

加密解密的区别

　　在每轮操作中,加密使用的PC2密钥顺序为0~15,解密使用的PC2密钥顺序为15~0.

完整代码

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

typedef char ElemType;
/*初始置换规则*/
ElemType IP[64]=
{
    57,49,41,33,25,17,9,1,59,51,43,35,27,19,11,3,
    61,53,45,37,29,21,13,5,63,55,47,39,31,23,15,7,
    56,48,40,32,24,16,8,0,58,50,42,34,26,18,10,2,
    60,52,44,36,28,20,12,4,62,54,46,38,30,22,14,6
};
/*逆置换规则*/
ElemType IP_1[64]=
{
    39,7,47,15,55,23,63,31,38,6,46,14,54,22,62,30,
    37,5,45,13,53,21,61,29,36,4,44,12,52,20,60,28,
    35,3,43,11,51,19,59,27,34,2,42,10,50,18,58,26,
    33,1,41,9,49,17,57,25,32,0,40,8,48,16,56,24
};
/*扩展置换表E盒*/
ElemType E[48]=
{
    31,0,1,2,3,4,3,4,5,6,7,8,
    7,8,9,10,11,12,11,12,13,14,15,16,
    15,16,17,18,19,20,19,20,21,22,23,24,
    23,24,25,26,27,28,27,28,29,30,31,0
};
/*直接置换表P盒*/
ElemType P[32]=
{
    15,6,19,20,28,11,27,16,0,14,22,25,4,17,30,9,
    1,7,23,13,31,26,2,8,18,12,29,5,21,10,3,24
};
/*代替表S盒*/
ElemType S[8][4][16]=
{
    /*S1*/
    {   {14,4,13,1,2,15,11,8,3,10,6,12,5,9,0,7},
        {0,15,7,4,14,2,13,1,10,6,12,11,9,5,3,8},
        {4,1,14,8,13,6,2,11,15,12,9,7,3,10,5,0},
        {15,12,8,2,4,9,1,7,5,11,3,14,10,0,6,13}
    },
    /*S2*/
    {   {15,1,8,14,6,11,3,4,9,7,2,13,12,0,5,10},
        {3,13,4,7,15,2,8,14,12,0,1,10,6,9,11,5},
        {0,14,7,11,10,4,13,1,5,8,12,6,9,3,2,15},
        {13,8,10,1,3,15,4,2,11,6,7,12,0,5,14,9}
    },
    /*S3*/
    {   {10,0,9,14,6,3,15,5,1,13,12,7,11,4,2,8},
        {13,7,0,9,3,4,6,10,2,8,5,14,12,11,15,1},
        {13,6,4,9,8,15,3,0,11,1,2,12,5,10,14,7},
        {1,10,13,0,6,9,8,7,4,15,14,3,11,5,2,12}
    },
    /*S4*/
    {   {7,13,14,3,0,6,9,10,1,2,8,5,11,12,4,15},
        {13,8,11,5,6,15,0,3,4,7,2,12,1,10,14,9},
        {10,6,9,0,12,11,7,13,15,1,3,14,5,2,8,4},
        {3,15,0,6,10,1,13,8,9,4,5,11,12,7,2,14}
    },
    /*S5*/
    {   {2,12,4,1,7,10,11,6,8,5,3,15,13,0,14,9},
        {14,11,2,12,4,7,13,1,5,0,15,10,3,9,8,6},
        {4,2,1,11,10,13,7,8,15,9,12,5,6,3,0,14},
        {11,8,12,7,1,14,2,13,6,15,0,9,10,4,5,3}
    },
    /*S6*/
    {   {12,1,10,15,9,2,6,8,0,13,3,4,14,7,5,11},
        {10,15,4,2,7,12,9,5,6,1,13,14,0,11,3,8},
        {9,14,15,5,2,8,12,3,7,0,4,10,1,13,11,6},
        {4,3,2,12,9,5,15,10,11,14,1,7,6,0,8,13}
    },
    /*S7*/
    {   {4,11,2,14,15,0,8,13,3,12,9,7,5,10,6,1},
        {13,0,11,7,4,9,1,10,14,3,5,12,2,15,8,6},
        {1,4,11,13,12,3,7,14,10,15,6,8,0,5,9,2},
        {6,11,13,8,1,4,10,7,9,5,0,15,14,2,3,12}
    },
span style=span style=span style=color: #800080;span style=926    /*S8*/
    {   {13,2,8,4,6,15,11,1,10,9,3,14,5,0,12,7},
        {1,15,13,8,10,3,7,4,12,5,6,11,0,14,9,2},
        {7,11,4,1,9,12,14,2,0,6,10,13,15,3,5,8},
        {2,1,14,7,4,10,8,13,15,12,9,0,3,5,6,11}
    }
};
/*子密钥生成表*/
ElemType PC1[56]=
{
    56,48,40,32,24,16,8,0,57,49,41,33,25,17,
    9,1,58,50,42,34,26,18,10,2,59,51,43,35,
    62,54,46,38,30,22,14,6,61,53,45,37,29,21,
    13,5,60,52,44,36,28,20,12,4,27,19,11,3
};
/*子密钥置换选择表*/
ElemType PC2[48]=
{
    13,16,10,23,0,4,2,27,14,5,20,9,22,18,11,3,
    25,7,15,6,26,19,12,1,40,51,30,36,46,54,29,39,
    50,44,32,47,43,48,38,55,33,52,45,41,49,35,28,31
};
/*每轮子密钥向左移动的位数*/
ElemType Step[16]=
{
    1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1
};
/*PC1置换*/
void PC_1_Trans(ElemType res[64],ElemType dst[56])
{
    int i;
    for(i=0; i<56; ++i)
    {
        dst[i]=res[(int)PC1[i]];
    }
    return;
}
/*循环左移*/
void Move(ElemType data[56],int index)
{
    ElemType temp[5];
    memcpy(temp,data,Step[index]);
    memcpy(temp+Step[index],data+28,Step[index]);
    memcpy(data,data+Step[index],28-Step[index]);
    memcpy(data+28-Step[index],temp,Step[index]);
    memcpy(data+28,data+28+Step[index],28-Step[index]);
    memcpy(data+56-Step[index],temp+Step[index],Step[index]);
    return;
}
/*PC2置换*/
void PC_2_Trans(ElemType res[56],ElemType dst[48])
{
    int i;
    for(i=0; i<48; ++i)
    {
        dst[i]=res[(int)PC2[i]];
    }
    return;
}
/*初始IP置换*/
void IPChange(ElemType data[64])
{
    int i;
    ElemType temp[64];
    memcpy(temp,data,64);
    for(i=0; i<64; ++i)
    {
        data[i]=temp[(int)IP[i]];
    }
    return;
}
/*E盒拓展*/
void E_Trans(ElemType data[48],ElemType key[32])
{
    int i;
    for(i=0; i<48; ++i)
    {
        data[i]=key[(int)E[i]];
    }
    return;
}
/*S盒置换*/
void S_Trans(ElemType data[48])
{
    int i,j,k,r,c,res;
    for(i=0; i<8; ++i)
    {
        j=i*6;
        k=i<<2;
        r=(data[j]<<1)+data[j+5];
        c=(data[j+1]<<3)+(data[j+2]<<2)+(data[j+3]<<1)+data[j+4];
        res=S[i][r][c];
        data[k]=(res&0x08)>>3;
        data[k+1]=(res&0x04)>>2;
        data[k+2]=(res&0x03)>>1;
        data[k+3]=res&0x01;
    }
    return;
}
/*P盒置换*/
void P_Trans(ElemType data[32])
{
    int i;
    ElemType temp[32];
    memcpy(temp,data,32);
    for(i=0; i<32; ++i)
    {
        data[i]=temp[(int)P[i]];
    }
    return;
}
/*IP逆置换*/
void IP_1_Change(char data[64])
{
    int i;
    ElemType temp[64];
    memcpy(temp,data,64);
    for(i=0; i<64; ++i)
    {
        data[i]=temp[(int)IP_1[i]];
    }
    return;
}
/*异或操作*/
void XOR(ElemType *dst,ElemType *res,int len)
{
    int i;
    for(i=0; i<len; ++i)
    {
        dst[i]^=res[i];
    }
    return;
}
/*辅助显示函数*/
void Show(ElemType *data,int len)
{
    int i;
    for(i=0; i<len; ++i)
    {
        printf("%d",data[i]);
    }
    printf("\n");
    return;
}
/*辅助二进制十六进制互转函数*/
void B2X(ElemType *bit,char *x,ElemType Mode)
{
    int i;
    if(Mode)
    {
        i=(bit[0]<<3)+(bit[1]<<2)+(bit[2]<<1)+bit[3];
        if(i<10)
        {
            *x='0'+i;
        }
        else
        {
            *x='A'+i-10;
        }
    }
    else
    {
        if(*x>='A'&&*x<='F')
        {
            i=*x-'A'+10;
        }
        else if(*x>='a'&&*x<='f')
        {
            i=*x-'a'+10;
        }
        else
        {
            i=*x-'0';
        }
        bit[0]=(i&0x08)>>3;
        bit[1]=(i&0x04)>>2;
        bit[2]=(i&0x03)>>1;
        bit[3]=i&0x01;
    }
    return;
}

void DES(ElemType StrText[64],ElemType KeyText[64],ElemType Mode)
{
    /*PC1子密钥,左串,右串,扩展右串,PC2子密钥*/
    ElemType PC1Key[56],LStr[32],RStr[32],ExRStr[48],PC2Key[16][48];
    int i;
    IPChange(StrText);
    for(i=0; i<32; ++i)
    {
        LStr[i]=StrText[i];
        RStr[i]=StrText[i+32];
    }
    PC_1_Trans(KeyText,PC1Key);
    for(i=0; i<16; ++i)
    {
        Move(PC1Key,i);
        PC_2_Trans(PC1Key,PC2Key[i]);
    }
    for(i=0; i<16; ++i)
    {
        E_Trans(ExRStr,RStr);
        if(Mode)
        {
            XOR(ExRStr,PC2Key[i],48);
        }
        else
        {
            XOR(ExRStr,PC2Key[15-i],48);
        }
        S_Trans(ExRStr);
        P_Trans(ExRStr);
        XOR(ExRStr,LStr,32);
        memcpy(LStr,RStr,32);
        memcpy(RStr,ExRStr,32);
    }
    for(i=0; i<32; ++i)
    {
        StrText[i]=RStr[i];
        StrText[i+32]=LStr[i];
    }
    IP_1_Change(StrText);
    puts(Mode?"密文:":"明文:");
    for(i=0; i<64; i+=4)
    {
        char j;
        B2X(&StrText[i],&j,1);
        printf("%c",j);
    }
    printf("\n");
    return;
}

int main()
{
    /*处理串,密钥,十六进制输入串*/
    ElemType Str[65],Key[65],A[17],B[17];
    int i,m;
    while(scanf("%s %s %d",A,B,&m)!=EOF)
    {
        for(i=0; i<16; ++i)
        {
            B2X(&Str[i<<2],&A[i],0);
            B2X(&Key[i<<2],&B[i],0);
        }
        DES(Str,Key,m);
    }
    return 0;
}

 

 

 

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