DES

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DES全称为Data Encryption Standard，即数据加密标准，是一种使用密钥加密的块算法，1977年被美国联邦政府的国家标准局确定为联邦资料处理标准（FIPS），并授权在非密级政府通信中使用，随后该算法在国际上广泛流传开来。需要注意的是，在某些文献中，作为算法的DES称为数据加密算法（Data Encryption Algorithm,DEA），已与作为标准的DES区分开来。
#include#include#include#include#define PLAIN_FILE_OPEN_ERROR -1#define KEY_FILE_OPEN_ERROR -2#define CIPHER_FILE_OPEN_ERROR -3#define OK 0;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)<>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("../config/lan_info_conf.bak","jinanteach","../config/lan_info_conf");    DES_Decrypt("../config/lan_info_conf","jinanteach","../config/lan_info_conf1");    return 0;}
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