一、Des加密算法简介
Des是Data Encryption Standard（数据加密标准）的缩写。它是由IBM公司研制的一种对称密码算法，对称性是指它使用同一个秘钥来加密和解密数据，与之相对应的RSA加密算法则是一种非对称密码算法。Des加密需要双方事先共同拟定一个秘钥，不对第三方公开。
Des还是一种分组加密算法，该算法每次处理固定长度的数据段称之为分组。典型的Des以64位为分组对数据进行加密，如果加密的数据长度不是64位，则会被0填充。
二、流程简介
- 储存表的函数
- 密钥初始置换 64->58
- 密钥左移
- 压缩密钥 56->48
- 产生K1-K16的16轮子密钥
- 明文初始置换 64->64
根据明文初始置换表进行置换，将得到的64位数据拆分为L0和R0,然后按照如下运算规则进行运算。 - 进行异或，E盒置换，S盒置换，P盒置换得出L1R1到L16R16
- 将R16L16进行64位置换得到二进制密文
- 将二进制密文转化为16进制即可得到密文
- 解密，将16轮子秘钥反向迭代
三、代码实现
明文：0123456789ABCDEF
秘钥：133457799BBCDFF1
密文：85E813540F0AB405
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
//定义枚举形全局变量
typedef enum
{
false = 0,
true = 1
} bool;
//十六轮子密钥
static bool SubKey[16][48]= {0};
//交换规则表
static char PC1_Table[56]=
{
57,49,41,33,25,17, 9, 1,58,50,42,34,26,18,
10, 2,59,51,43,35,27,19,11, 3,60,52,44,36,
63,55,47,39,31,23,15, 7,62,54,46,38,30,22,
14, 6,61,53,45,37,29,21,13, 5,28,20,12, 4
};
// 移位表
static char Move_Table[16]=
{
1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1
};
//交换表二
static char PC2_Table[48]=
{
14,17,11,24, 1, 5, 3,28,15, 6,21,10,
23,19,12, 4,26, 8,16, 7,27,20,13, 2,
41,52,31,37,47,55,30,40,51,45,33,48,
44,49,39,56,34,53,46,42,50,36,29,32
};
// IP置换表
const char IP_Table[64]=
{
58,50,42,34,26,18,10, 2,60,52,44,36,28,20,12, 4,
62,54,46,38,30,22,14, 6,64,56,48,40,32,24,16, 8,
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
};
// E扩展表
static char E_Table[48]=
{
32, 1, 2, 3, 4, 5, 4, 5, 6, 7, 8, 9,
8, 9,10,11,12,13,12,13,14,15,16,17,
16,17,18,19,20,21,20,21,22,23,24,25,
24,25,26,27,28,29,28,29,30,31,32, 1
};
static int S_Box[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, 0, 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, 0, 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
};
//P置换表
static char P_Table[32]=
{
16, 7,20,21,29,12,28,17, 1,15,23,26, 5,18,31,10,
2, 8,24,14,32,27, 3, 9,19,13,30, 6,22,11, 4,25
};
//IP_1表
const char IP1_Table[64]=
{
40, 8,48,16,56,24,64,32,39, 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
};
void SetKey(char My_key[16]); //生成16轮的子密钥；
void HexToBit(bool * Data_out,char * Data_in,int Num);//16进制转化为2进制
void Bitcopy(bool * Data_out, bool * Data_in,int Num);//数组拷贝
void TableReplace( bool *Data_out, bool * Data_in,const char *Table,int Num); //置换
void Loop_bit(bool * Data_out,int movstep,int len); //左移位
void Run_Des(char My_message[16],char HexMssage[16]);//des的轮加密算法
void F_change(bool Data_out[32],bool Data_in[48]);
void Xor(bool * Message_out,bool * Message_in,int Num);//异或操作
void S_change(bool * Data_out, bool * Data_in);//S盒变换
void BitToHex(char Data_out[16],bool Data_in[64],int Num);//二进制转化为16进制
void S_HexToBit(bool * Data_out,int Data_in,int Num);
void Run_desDes(char My_message[8],char HexMessage[16]);//des的轮解密算法
int main()
{
int i=0;
char My_Key[16]= {0}; //记录秘钥
char My_Message[16]= {0}; //记录明文
char Message_hex[16]= {0}; //记录密文
printf("请输入你需要加密的内容（16Byte)：\n");
gets(My_Message);
printf("请输入你的加密秘钥（16Byte):\n");
gets(My_Key);
i=strlen(My_Key);
while(i!=16)
{
printf("请输入你的加密秘钥（16Byte):\n");
gets(My_Key);
i=0;
i=strlen(My_Key);
}
SetKey(My_Key);//生成16轮子秘钥
Run_Des(My_Message,Message_hex);//加密
printf("最终密文为：");
for(i=0; i<16; i++)
{
printf("%c",Message_hex[i]);
}
printf("\n\n\n");
printf("*******************************************解密过程**************************************************");
Run_desDes(My_Message,Message_hex);
printf("\n解密结果：");
for(i=0; i<16; i++)
{
printf("%c",My_Message[i]);
}
return 0;
}
void Bitcopy(bool * Data_out, bool * Data_in,int Num) //二进制数组拷贝
{
int i=0;
for(i=0; i<Num; i++)
{
Data_out[i]=Data_in[i];
}
}
void SetKey(char My_key[16])
{
int i;
static bool Key_bit[64]= {0}; //秘钥的二进制缓存
static bool *Key_bit_L,*Key_bit_R;
Key_bit_L=&Key_bit[0];//key的左28位
Key_bit_R=&Key_bit[28];//key的右28位
HexToBit(Key_bit,My_key,16);
static bool Key_bit1[64]= {0};
Bitcopy(Key_bit1,Key_bit,64);
TableReplace(Key_bit,Key_bit1,PC1_Table,64);
printf("\n");
for(i=0; i<16; i++)
{
Loop_bit(Key_bit_L,Move_Table[i],28);
Loop_bit(Key_bit_R,Move_Table[i],28);
TableReplace(SubKey[i],Key_bit,PC2_Table,48);
}
printf("K1:");
for(i=0; i<48; i++)
{
printf("%d",SubKey[0][i]);
}
printf("\nK16:");
for(i=0; i<48; i++)
{
printf("%d",SubKey[15][i]);
}
printf("\n");
}
void HexToBit(bool * Data_out,char * Data_in,int Num) //十六进制转二进制
{
int i,j=0;
for(i=0; i<Num; i++)
{
switch(Data_in[i])
{
case '0':
Data_out[j]=0;
Data_out[j+1]=0;
Data_out[j+2]=0;
Data_out[j+3]=0;
break;
case '1':
Data_out[j]=0;
Data_out[j+1]=0;
Data_out[j+2]=0;
Data_out[j+3]=1;
break;
case '2':
Data_out[j]=0;
Data_out[j+1]=0;
Data_out[j+2]=1;
Data_out[j+3]=0;
break;
case '3':
Data_out[j]=0;
Data_out[j+1]=0;
Data_out[j+2]=1;
Data_out[j+3]=1;
break;
case '4':
Data_out[j]=0;
Data_out[j+1]=1;
Data_out[j+2]=0;
Data_out[j+3]=0;
break;
case '5':
Data_out[j]=0;
Data_out[j+1]=1;
Data_out[j+2]=0;
Data_out[j+3]=1;
break;
case '6':
Data_out[j]=0;
Data_out[j+1]=1;
Data_out[j+2]=1;
Data_out[j+3]=0;
break;
case '7':
Data_out[j]=0;
Data_out[j+1]=1;
Data_out[j+2]=1;
Data_out[j+3]=1;
break;
case '8':
Data_out[j]=1;
Data_out[j+1]=0;
Data_out[j+2]=0;
Data_out[j+3]=0;
break;
case '9':
Data_out[j]=1;
Data_out[j+1]=0;
Data_out[j+2]=0;
Data_out[j+3]=1;
break;
case 'A':
Data_out[j]=1;
Data_out[j+1]=0;
Data_out[j+2]=1;
Data_out[j+3]=0;
break;
case 'B':
Data_out[j]=1;
Data_out[j+1]=0;
Data_out[j+2]=1;
Data_out[j+3]=1;
break;
case 'C':
Data_out[j]=1;
Data_out[j+1]=1;
Data_out[j+2]=0;
Data_out[j+3]=0;
break;
case 'D':
Data_out[j]=1;
Data_out[j+1]=1;
Data_out[j+2]=0;
Data_out[j+3]=1;
break;
case 'E':
Data_out[j]=1;
Data_out[j+1]=1;
Data_out[j+2]=1;
Data_out[j+3]=0;
break;
case 'F':
Data_out[j]=1;
Data_out[j+1]=1;
Data_out[j+2]=1;
Data_out[j+3]=1;
break;
}
j=j+4;
}
/*for(i=0;i<64;i++){
printf("%d",Data_out[i]);
}*/
}
void TableReplace( bool *Data_out, bool * Data_in,const char *Table,int Num) // 置换算法
{
int i=0;
static bool Temp[256]= {0};
for(i=0; i<Num; i++)
{
Temp[i]=Data_in[Table[i]-1];
}
Bitcopy(Data_out,Temp,Num);
}
void Loop_bit(bool * Data_out,int movstep,int len)
{
static bool Temp[256]= {0};
Bitcopy(Temp,Data_out,movstep);
Bitcopy(Data_out,Data_out+movstep,len-movstep);
Bitcopy(Data_out+len-movstep,Temp,movstep);
/*Temp=Data_out;
Temp[movstep]='\0';
Data_out=Data_out+movstep;
Data_out+(len-movstep)=Temp;*/
}
void Run_Des(char My_message[16],char HexMssage[16])
{
int i,j;
static bool Message_bit[64]= {0};
static bool *Message_bit_L=&Message_bit[0],*Message_bit_R=&Message_bit[32];
static bool Temp[32]= {0};
HexToBit(Message_bit,My_message,16);
/*for(i=0;i<64;i++){
printf("%d",Message_bit[i]);
}*/
static bool Message_bit1[64]= {0};
Bitcopy(Message_bit1,Message_bit,64);
TableReplace(Message_bit,Message_bit1,IP_Table,64);
/*for(i=0;i<64;i++){
printf("%d",Message_bit[i]);
}*/
for(i=0; i<16; i++)
{
Bitcopy(Temp,Message_bit_R,32);
printf("\nR:");
for(j=0; j<32; j++)
{
printf("%d",Message_bit_R[j]);
}
F_change(Message_bit_R,SubKey[i]);
printf("\nR:");
for(j=0; j<32; j++)
{
printf("%d",Message_bit_R[j]);
}
Xor(Message_bit_R,Message_bit_L,32);
Bitcopy(Message_bit_L,Temp,32);
printf("\nL:");
for(j=0; j<32; j++)
{
printf("%d",Message_bit_L[j]);
}
printf("\nR:");
for(j=0; j<32; j++)
{
printf("%d",Message_bit_R[j]);
}
printf("\n");
}
printf("\n");
static bool Message_bit2[64]= {0};
Bitcopy(Message_bit2,Message_bit_R,32);
Bitcopy(Message_bit2+32,Message_bit_L,32);
TableReplace(Message_bit,Message_bit2,IP1_Table,64);
printf("\nT:");
for(i=0; i<64; i++)
{
printf("%d",Message_bit[i]);
}
printf("\n");
BitToHex(HexMssage,Message_bit,64);
}
void F_change(bool Data_out[32],bool Data_in[48]) // f函数；
{
static bool Message_E[48]= {0}; //存放E置换的结果；
int i=0;
TableReplace(Message_E,Data_out,E_Table,48);//E表置换
printf("\nE:");
for(i=0; i<48; i++)
{
printf("%d",Message_E[i]);
}
printf("\n");
Xor(Message_E,Data_in,48);
S_change(Data_out,Message_E); // S盒变换
printf("S:");
for(i=0; i<32; i++)
{
printf("%d",Data_out[i]);
}
printf("\n");
TableReplace(Data_out,Data_out,P_Table,32); //P置换
printf("P:");
for(i=0; i<32; i++)
{
printf("%d",Data_out[i]);
}
}
void Xor(bool * Message_out,bool * Message_in,int Num)//执行异或
{
int i;
for(i=0; i<Num; i++)
{
if(Message_in[i]==Message_out[i])
{
Message_out[i]=0;
}
else
{
Message_out[i]=1;
}
}
}
void S_change(bool * Data_out, bool * Data_in) //S盒变换
{
int i;
int r=0,c=0;//S盒的行和列；
for(i=0; i<8; i++,Data_in=Data_in+6,Data_out=Data_out+4)
{
r=Data_in[0]*2+Data_in[5]*1;
c=Data_in[1]*8+Data_in[2]*4+Data_in[3]*2+Data_in[4]*1;
S_HexToBit(Data_out,S_Box[i][r][c],4);
//printf("%d\n",S_Box[0][r][c]);
}
}
void BitToHex(char Data_out[16],bool Data_in[64],int Num)
{
int i,j=0;
int sum=0;
for(i=0,j=0; i<Num/4; i++,j+=4)
{
sum=(Data_in[j]*8+Data_in[j+1]*4+Data_in[j+2]*2+Data_in[j+3]);
if(sum<=9&&sum>=0)
{
Data_out[i]=sum+'0';
}
else
{
Data_out[i]=sum-10+'A';
}
}
}
void S_HexToBit(bool * Data_out,int Data_in,int Num) //十六进制转二进制
{
int j=0;
switch(Data_in )
{
case 0:
Data_out[j]=0;
Data_out[j+1]=0;
Data_out[j+2]=0;
Data_out[j+3]=0;
break;
case 1:
Data_out[j]=0;
Data_out[j+1]=0;
Data_out[j+2]=0;
Data_out[j+3]=1;
break;
case 2:
Data_out[j]=0;
Data_out[j+1]=0;
Data_out[j+2]=1;
Data_out[j+3]=0;
break;
case 3:
Data_out[j]=0;
Data_out[j+1]=0;
Data_out[j+2]=1;
Data_out[j+3]=1;
break;
case 4:
Data_out[j]=0;
Data_out[j+1]=1;
Data_out[j+2]=0;
Data_out[j+3]=0;
break;
case 5:
Data_out[j]=0;
Data_out[j+1]=1;
Data_out[j+2]=0;
Data_out[j+3]=1;
break;
case 6:
Data_out[j]=0;
Data_out[j+1]=1;
Data_out[j+2]=1;
Data_out[j+3]=0;
break;
case 7:
Data_out[j]=0;
Data_out[j+1]=1;
Data_out[j+2]=1;
Data_out[j+3]=1;
break;
case 8:
Data_out[j]=1;
Data_out[j+1]=0;
Data_out[j+2]=0;
Data_out[j+3]=0;
break;
case 9:
Data_out[j]=1;
Data_out[j+1]=0;
Data_out[j+2]=0;
Data_out[j+3]=1;
break;
case 10:
Data_out[j]=1;
Data_out[j+1]=0;
Data_out[j+2]=1;
Data_out[j+3]=0;
break;
case 11:
Data_out[j]=1;
Data_out[j+1]=0;
Data_out[j+2]=1;
Data_out[j+3]=1;
break;
case 12:
Data_out[j]=1;
Data_out[j+1]=1;
Data_out[j+2]=0;
Data_out[j+3]=0;
break;
case 13:
Data_out[j]=1;
Data_out[j+1]=1;
Data_out[j+2]=0;
Data_out[j+3]=1;
break;
case 14:
Data_out[j]=1;
Data_out[j+1]=1;
Data_out[j+2]=1;
Data_out[j+3]=0;
break;
case 15:
Data_out[j]=1;
Data_out[j+1]=1;
Data_out[j+2]=1;
Data_out[j+3]=1;
break;
}
/*for(i=0;i<64;i++){
printf("%d",Data_out[i]);
}*/
}
void Run_desDes(char My_message[8],char HexMessage[16])// DES轮解密算法；
{
int i=0;
static bool Message_bit[64]= {0};
static bool * Message_bit_L=&Message_bit[0], * Message_bit_R=&Message_bit[32];
static bool Temp[32]= {0};
HexToBit(Message_bit,HexMessage,64);
static bool Message_bit1[64];
Bitcopy(Message_bit1,Message_bit,64);
TableReplace(Message_bit,Message_bit,IP_Table,64);
printf("\n初始置换结果为:");
for(i=0; i<64; i++)
{
printf("%d",Message_bit[i]);
}
printf("\nL0:");
for(i=0; i<32; i++)
{
printf("%d",Message_bit_L[i]);
}
printf("\nR0:");
for(i=0; i<32; i++)
{
printf("%d",Message_bit_R[i]);
}
printf("\n");
for(i=15; i>=0; i--)
{
Bitcopy(Temp,Message_bit_R,32);
F_change(Message_bit_R,SubKey[i]);
Xor(Message_bit_R,Message_bit_L,32);
Bitcopy(Message_bit_L,Temp,32);
printf("\n");
}
static bool Message_bit2[64]= {0};
Bitcopy(Message_bit2,Message_bit_R,32);
Bitcopy(Message_bit2+32,Message_bit_L,32);
TableReplace(Message_bit,Message_bit2,IP1_Table,64);
printf("\nT:");
for(i=0; i<64; i++)
{
printf("%d",Message_bit[i]);
}
printf("\n");
BitToHex(My_message,Message_bit,64);
}四、最终结果
加密：
解密：
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