DES 算法

#include "stdio.h"
#include "time.h"
#include "stdlib.h"
#include<string.h>

#define PLAIN_FILE_OPEN_ERROR -1
#define KEY_FILE_OPEN_ERROR -2
#define CIPHER_FILE_OPEN_ERROR -3
#define OK 1;
typedef char ElemType;
       /* 初始置换表IP */
int IP_Table[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};
/* 逆初始置换表IP^-1 */
int IP_1_Table[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};

/* 扩充置换表E */
int E_Table[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};

/* 置换函数P */
int P_Table[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};

/* S盒 */
int 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}},
/* 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}}};
/* 置换选择1 */
int PC_1[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};

/* 置换选择2 */
int PC_2[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,
              50,44,32,46,43,48,38,55,
              33,52,45,41,49,35,28,31};

/* 对左移次数的规定 */
int MOVE_TIMES[16] = {1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1};
int ByteToBit(ElemType ch,ElemType bit[8]);
int BitToByte(ElemType bit[8],ElemType *ch);
int Char8ToBit64(ElemType ch[8],ElemType bit[64]);
int Bit64ToChar8(ElemType bit[64],ElemType ch[8]);
int DES_MakeSubKeys(ElemType key[64],ElemType subKeys[16][48]);
int DES_PC1_Transform(ElemType key[64], ElemType tempbts[56]);
int DES_PC2_Transform(ElemType key[56], ElemType tempbts[48]);
int DES_ROL(ElemType data[56], int time);
int DES_IP_Transform(ElemType data[64]);
int DES_IP_1_Transform(ElemType data[64]);
int DES_E_Transform(ElemType data[48]);
int DES_P_Transform(ElemType data[32]);
int DES_SBOX(ElemType data[48]);
int DES_XOR(ElemType R[48], ElemType L[48],int count);
int DES_Swap(ElemType left[32],ElemType right[32]);
int DES_EncryptBlock(ElemType plainBlock[8], ElemType subKeys[16][48], ElemType cipherBlock[8]);
int DES_DecryptBlock(ElemType cipherBlock[8], ElemType subKeys[16][48], ElemType plainBlock[8]);
int DES_Encrypt(char *plainFile, char *keyStr,char *cipherFile);
int DES_Decrypt(char *cipherFile, char *keyStr,char *plainFile);
                             /* 字节转换成二进制 */
int ByteToBit(ElemType ch, ElemType bit[8]){
    int cnt;
    for(cnt = 0;cnt < 8; cnt++){
        *(bit+cnt) = (ch>>cnt)&1;
    }
    return 0;
}

/* 二进制转换成字节 */
int BitToByte(ElemType bit[8],ElemType *ch){
    int cnt;
    for(cnt = 0;cnt < 8; cnt++){
        *ch |= *(bit + cnt)<<cnt;
    }
    return 0;
}

/* 将长度为8的字符串转为二进制位串 */
int Char8ToBit64(ElemType ch[8],ElemType bit[64]){
    int cnt;
    for(cnt = 0; cnt < 8; cnt++){       
        ByteToBit(*(ch+cnt),bit+(cnt<<3));
    }
    return 0;
}

/* 将二进制位串转为长度为8的字符串 */
int Bit64ToChar8(ElemType bit[64],ElemType ch[8]){
    int cnt;
    memset(ch,0,8);
    for(cnt = 0; cnt < 8; cnt++){
        BitToByte(bit+(cnt<<3),ch+cnt);
    }
    return 0;
}

/* 生成子密钥 */
int DES_MakeSubKeys(ElemType key[64],ElemType subKeys[16][48]){
    ElemType temp[56];
    int cnt;
    DES_PC1_Transform(key,temp);/* PC1置换 */
    for(cnt = 0; cnt < 16; cnt++){/* 16轮跌代，产生16个子密钥 */
        DES_ROL(temp,MOVE_TIMES[cnt]);/* 循环左移 */
        DES_PC2_Transform(temp,subKeys[cnt]);/* PC2置换，产生子密钥 */
    }
    return 0;
}

/* 密钥置换1 */
int DES_PC1_Transform(ElemType key[64], ElemType tempbts[56]){
    int cnt;   
    for(cnt = 0; cnt < 56; cnt++){
        tempbts[cnt] = key[PC_1[cnt]];
    }
    return 0;
}

/* 密钥置换2 */
int DES_PC2_Transform(ElemType key[56], ElemType tempbts[48]){
    int cnt;
    for(cnt = 0; cnt < 48; cnt++){
        tempbts[cnt] = key[PC_2[cnt]];
    }
    return 0;
}

/* 循环左移 */
int DES_ROL(ElemType data[56], int time){   
    ElemType temp[56];

    /* 保存将要循环移动到右边的位 */
    memcpy(temp,data,time);
    memcpy(temp+time,data+28,time);
   
    /* 前28位移动 */
    memcpy(data,data+time,28-time);
    memcpy(data+28-time,temp,time);

    /* 后28位移动 */
    memcpy(data+28,data+28+time,28-time);
    memcpy(data+56-time,temp+time,time);   

    return 0;
}

/* IP置换 */
int DES_IP_Transform(ElemType data[64]){
    int cnt;
    ElemType temp[64];
    for(cnt = 0; cnt < 64; cnt++){
        temp[cnt] = data[IP_Table[cnt]];
    }
    memcpy(data,temp,64);
    return 0;
}

/* IP逆置换 */
int DES_IP_1_Transform(ElemType data[64]){
    int cnt;
    ElemType temp[64];
    for(cnt = 0; cnt < 64; cnt++){
        temp[cnt] = data[IP_1_Table[cnt]];
    }
    memcpy(data,temp,64);
    return 0;
}

/* 扩展置换 */
int DES_E_Transform(ElemType data[48]){
    int cnt;
    ElemType temp[48];
    for(cnt = 0; cnt < 48; cnt++){
        temp[cnt] = data[E_Table[cnt]];
    }   
    memcpy(data,temp,48);
    return 0;
}

/* P置换 */
int DES_P_Transform(ElemType data[32]){
    int cnt;
    ElemType temp[32];
    for(cnt = 0; cnt < 32; cnt++){
        temp[cnt] = data[P_Table[cnt]];
    }   
    memcpy(data,temp,32);
    return 0;
}

/* 异或 */
int DES_XOR(ElemType R[48], ElemType L[48] ,int count){
    int cnt;
    for(cnt = 0; cnt < count; cnt++){
        R[cnt] ^= L[cnt];
    }
    return 0;
}

/* S盒置换 */
int DES_SBOX(ElemType data[48]){
    int cnt;
    int line,row,output;
    int cur1,cur2;
    for(cnt = 0; cnt < 8; cnt++){
        cur1 = cnt*6;
        cur2 = cnt<<2;
       
        /* 计算在S盒中的行与列 */
        line = (data[cur1]<<1) + data[cur1+5];
        row = (data[cur1+1]<<3) + (data[cur1+2]<<2)
            + (data[cur1+3]<<1) + data[cur1+4];
        output = S[cnt][line][row];

        /* 化为2进制 */
        data[cur2] = (output&0X08)>>3;
        data[cur2+1] = (output&0X04)>>2;
        data[cur2+2] = (output&0X02)>>1;
        data[cur2+3] = output&0x01;
    }   
    return 0;
}

/* 交换 */
int DES_Swap(ElemType left[32], ElemType right[32]){
    ElemType temp[32];
    memcpy(temp,left,32);   
    memcpy(left,right,32);   
    memcpy(right,temp,32);
    return 0;
}

/* 加密单个分组 */
int DES_EncryptBlock(ElemType plainBlock[8], ElemType subKeys[16][48], ElemType cipherBlock[8]){
    ElemType plainBits[64];
    ElemType copyRight[48];
    int cnt;

    Char8ToBit64(plainBlock,plainBits);       
    /* 初始置换（IP置换） */
    DES_IP_Transform(plainBits);

    /* 16轮迭代 */
    for(cnt = 0; cnt < 16; cnt++){       
        memcpy(copyRight,plainBits+32,32);
        /* 将右半部分进行扩展置换，从32位扩展到48位 */
        DES_E_Transform(copyRight);
        /* 将右半部分与子密钥进行异或操作 */
        DES_XOR(copyRight,subKeys[cnt],48);   
        /* 异或结果进入S盒，输出32位结果 */
        DES_SBOX(copyRight);
        /* P置换 */
        DES_P_Transform(copyRight);
        /* 将明文左半部分与右半部分进行异或 */
        DES_XOR(plainBits,copyRight,32);
        if(cnt != 15){
            /* 最终完成左右部的交换 */
            DES_Swap(plainBits,plainBits+32);
        }
    }
    /* 逆初始置换（IP^1置换） */
    DES_IP_1_Transform(plainBits);
    Bit64ToChar8(plainBits,cipherBlock);
    return 0;
}

/* 解密单个分组 */
int DES_DecryptBlock(ElemType cipherBlock[8], ElemType subKeys[16][48],ElemType plainBlock[8]){
    ElemType cipherBits[64];
    ElemType copyRight[48];
    int cnt;

    Char8ToBit64(cipherBlock,cipherBits);       
    /* 初始置换（IP置换） */
    DES_IP_Transform(cipherBits);
   
    /* 16轮迭代 */
    for(cnt = 15; cnt >= 0; cnt--){       
        memcpy(copyRight,cipherBits+32,32);
        /* 将右半部分进行扩展置换，从32位扩展到48位 */
        DES_E_Transform(copyRight);
        /* 将右半部分与子密钥进行异或操作 */
        DES_XOR(copyRight,subKeys[cnt],48);       
        /* 异或结果进入S盒，输出32位结果 */
        DES_SBOX(copyRight);
        /* P置换 */
        DES_P_Transform(copyRight);       
        /* 将明文左半部分与右半部分进行异或 */
        DES_XOR(cipherBits,copyRight,32);
        if(cnt != 0){
            /* 最终完成左右部的交换 */
            DES_Swap(cipherBits,cipherBits+32);
        }
    }
    /* 逆初始置换（IP^1置换） */
    DES_IP_1_Transform(cipherBits);
    Bit64ToChar8(cipherBits,plainBlock);
    return 0;
}

/* 加密文件 */
int DES_Encrypt(char *plainFile, char *keyStr,char *cipherFile){
    FILE *plain,*cipher;
    int count;
    ElemType plainBlock[8],cipherBlock[8],keyBlock[8];
    ElemType bKey[64];
    ElemType subKeys[16][48];
    if((plain = fopen(plainFile,"rb")) == NULL){
        return PLAIN_FILE_OPEN_ERROR;
    }   
    if((cipher = fopen(cipherFile,"wb")) == NULL){
        return CIPHER_FILE_OPEN_ERROR;
    }
    /* 设置密钥 */
    memcpy(keyBlock,keyStr,8);
    /* 将密钥转换为二进制流 */
    Char8ToBit64(keyBlock,bKey);
    /* 生成子密钥 */
    DES_MakeSubKeys(bKey,subKeys);
   
    while(!feof(plain)){
        /* 每次读8个字节，并返回成功读取的字节数 */
        if((count = fread(plainBlock,sizeof(char),8,plain)) == 8){
            DES_EncryptBlock(plainBlock,subKeys,cipherBlock);
            fwrite(cipherBlock,sizeof(char),8,cipher);   
        }
    }
    if(count){
        /* 填充 */
        memset(plainBlock + count,'\0',7 - count);
        /* 最后一个字符保存包括最后一个字符在内的所填充的字符数量 */
        plainBlock[7] = 8 - count;
        DES_EncryptBlock(plainBlock,subKeys,cipherBlock);
        fwrite(cipherBlock,sizeof(char),8,cipher);
    }
    fclose(plain);
    fclose(cipher);
return OK;
}

/* 解密文件 */
int DES_Decrypt(char *cipherFile, char *keyStr,char *plainFile){
    FILE *plain, *cipher;
    int count,times = 0;
    long fileLen;
    ElemType plainBlock[8],cipherBlock[8],keyBlock[8];
    ElemType bKey[64];
    ElemType subKeys[16][48];
    if((cipher = fopen(cipherFile,"rb")) == NULL){
        return CIPHER_FILE_OPEN_ERROR;
    }
    if((plain = fopen(plainFile,"wb")) == NULL){
        return PLAIN_FILE_OPEN_ERROR;
    }

    /* 设置密钥 */
    memcpy(keyBlock,keyStr,8);
    /* 将密钥转换为二进制流 */
    Char8ToBit64(keyBlock,bKey);
    /* 生成子密钥 */
    DES_MakeSubKeys(bKey,subKeys);

    /* 取文件长度     */
    fseek(cipher,0,SEEK_END);    /* 将文件指针置尾 */
    fileLen = ftell(cipher);    /* 取文件指针当前位置 */
    rewind(cipher);                /* 将文件指针重指向文件头 */
    while(1){
        /* 密文的字节数一定是8的整数倍 */
        fread(cipherBlock,sizeof(char),8,cipher);
        DES_DecryptBlock(cipherBlock,subKeys,plainBlock);                       
        times += 8;
        if(times < fileLen){
            fwrite(plainBlock,sizeof(char),8,plain);
        }
        else{
            break;
        }
    }
    /* 判断末尾是否被填充 */
    if(plainBlock[7] < 8){
        for(count = 8 - plainBlock[7]; count < 7; count++){
            if(plainBlock[count] != '\0'){
                break;
            }
        }
    }   
    if(count == 7){/* 有填充 */
        fwrite(plainBlock,sizeof(char),8 - plainBlock[7],plain);
    }
    else{/* 无填充 */
        fwrite(plainBlock,sizeof(char),8,plain);
    }

    fclose(plain);
    fclose(cipher);
return OK;
}
int main()
{    DES_Encrypt("1.txt","key.txt","2.txt");
    system("pause");
    DES_Decrypt("2.txt","key.txt","3.txt");
    getchar();
    return 0;
}

自动生成2.txt和3.txt的加密后和解密后的文件。