DES加密算法C++实现
2018-07-20 来源：open-open
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#define ENCRYPT 1
#define DECRYPT 0
static void printHex ( char *cmd, int len );
static void printArray ( const char *In, int len );
static void F_func ( bool In[32], const bool Ki[48] ); // f函数
static void S_func ( bool Out[32], const bool In[48] ); // S盒代替
static void Transform ( bool *Out, bool *In, const char *Table, int len ); // 变换
static void Xor ( bool *InA, const bool *InB, int len ); // 异或
static void RotateL ( bool *In, int len, int loop ); // 循环左移
static void ByteToBit ( bool *Out, const char *In, int bits ); // 字节组转换成位组
static void BitToByte ( char *Out, const bool *In, int bits ); // 位组转换成字节组
// 16位子密钥
static bool SubKey[16][48];
// 64位经过PC1转换为56位 (PC-1)
const 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
};
// 左移
const static char LOOP_Table[16] =
{
1, 1, 2, 2, 2, 2, 2, 2,
1, 2, 2, 2, 2, 2, 2, 1
};
// 排列选择 2 (PC-2)
const 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
};
// Ri_1（32位）经过变换E后膨胀为48位 (E) void F_func
static const 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
};
// 8个4比特合并为32比特的排列 P
const 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,
};
// 经过S盒 S-boxes
const static char 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, 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 }
}
};
// 初始排列 (IP)
const static 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
};
// L16与R16合并后经过IP_1的最终排列 (IP**-1)
const static char IPR_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 Des_SetKey ( const char Key[8] ); //生成子密钥
void Des_Run ( char Out[8], char In[8], bool Type ); //DES算法
void main ( int argc, char *argv[] )
{
char key[12]={1,2,3,4,5,6,7,8};
char str[12]="Hello";
char str2[12];
//printArray( PC2_Table, sizeof(PC2_Table)/sizeof(PC2_Table[0]) );
printf ( "Before encrypting: " );
puts ( str );
Des_SetKey ( key );
memset ( str2, 0, sizeof ( str2 ) );
Des_Run ( str2, str, ENCRYPT );
printf ( "After encrypting: " );
printHex ( str2, 8 );
memset ( str, 0, sizeof ( str ) );
printf ( "After decrypting: " );
Des_Run ( str, str2, DECRYPT );
puts ( str );
}
void Des_SetKey ( const char Key[8] )
{
int i;
static bool K[64], *KL = &K[0], *KR = &K[28];
ByteToBit ( K, Key, 64 ); //转换为二进制
Transform ( K, K, PC1_Table, 56 ); //64比特的密钥K，经过PC-1后，生成56比特的串。
//生成16个子密钥
for ( i=0; i<16; i++ )
{
//循环左移，合并
RotateL ( KL, 28, LOOP_Table[i] );
RotateL ( KR, 28, LOOP_Table[i] );
Transform ( SubKey[i], K, PC2_Table, 48 );
}
}
void Des_Run ( char Out[8], char In[8], bool Type )
{
int i;
static bool M[64], tmp[32], *Li = &M[0], *Ri = &M[32];
//转换为64位的数据块
ByteToBit ( M, In, 64 );
//IP置换 （初始）
Transform ( M, M, IP_Table, 64 );
//该比特串被分为32位的L0和32位的R0两部分。
if ( Type == ENCRYPT )
{
//16轮置换
for ( i=0; i<16; i++ )
{
memcpy ( tmp, Ri, 32 );
// R[i] = L[i-1] xor f(R[i-1], K[i])
F_func ( Ri, SubKey[i] );
// 2.4.6 Exclusive-or the resulting value with L[i-1].
// R[I]=P XOR L[I-1]
Xor ( Ri, Li, 32 );
// L[i] = R[i-1]
memcpy ( Li, tmp, 32 );
}
}
else
{
// 如果解密则反转子密钥顺序
for ( i=15; i>=0; i-- )
{
memcpy ( tmp, Li, 32 );
F_func ( Li, SubKey[i] );
Xor ( Li, Ri, 32 );
memcpy ( Ri, tmp, 32 );
}
}
//R16与L16合并成64位的比特串。R16一定要排在L16前面。R16与L16合并后成的比特串，经过置换IP-1后所得的比特串就是密文。
Transform ( M, M, IPR_Table, 64 );
BitToByte ( Out, M, 64 );
}
//将32比特的输入再转化为32比特的输出
void F_func ( bool In[32], const bool Ki[48] )
{
static bool MR[48];
//输入Ri-1(32比特)经过变换E后，膨胀为48比特
Transform ( MR, In, E_Table, 48 );
//异或
Xor ( MR, Ki, 48 );
//膨胀后的比特串分为8组，每组6比特。各组经过各自的S盒后，又变为4比特(具体过程见后)，合并后又成为32比特。
S_func ( In, MR );
//该32比特经过P变换后，输出的比特串才是32比特的f (Ri-1,Ki)。
Transform ( In, In, P_Table, 32 );
}
void S_func ( bool Out[32], const bool In[48] )
{
char j,m,n;
//膨胀后的比特串分为8组，每组6比特。
for ( j=0; j<8; j++,In+=6,Out+=4 )
{
//在其输入In[0],In[1],In[2],In[3],In[4],In[5]中，计算出m=In[0]*2+In[5], n=In[4]+In[3]*2+In[2]*4+In[1]*8，再从Sj表中查出m行，n列的值Smn。将Smn化为二进制，即得Si盒的输出。
m = ( In[0]<<1 ) + In[5];
n = ( In[1]<<3 ) + ( In[2]<<2 ) + ( In[3]<<1 ) + In[4];
ByteToBit ( Out, &S_Box[ ( int ) j][ ( int ) m][ ( int ) n], 4 );
}
}
// 打印指定位置指定长度HEX值
static void printHex ( char *cmd, int len )
{
int i;
for ( i=0; i<len; i++ )
{
printf ( "[%02X]", ( unsigned char ) cmd[i] );
}
printf ( "\n" );
}
// 打印数组测试用
static void printArray ( const char *In, int len )
{
int i;
char tmp[256];
memset ( tmp, 0, sizeof ( tmp ) );
for ( i=0; i<len; i++ )
{
tmp[ ( int ) In[i]]=In[i];
}
for ( i=0; i<len; i++ )
{
printf ( "[%02d]", ( unsigned char ) tmp[i] );
}
printf ( "\n" );
}
void Transform ( bool *Out, bool *In, const char *Table, int len )
{
int i;
static bool tmp[256];
for ( i=0; i<len; i++ )
{
tmp[i] = In[ Table[i]-1 ];
}
memcpy ( Out, tmp, len );
}
void Xor ( bool *InA, const bool *InB, int len )
{
int i;
for ( i=0; i<len; i++ )
{
InA[i] ^= InB[i];
}
}
void RotateL ( bool *In, int len, int loop )
{
static bool tmp[256]; // Sample: loop=2
memcpy ( tmp, In, loop ); // In=12345678 tmp=12
memcpy ( In, In+loop, len-loop ); // In=345678
memcpy ( In+len-loop, tmp, loop ); // In=34567812
}
// Sample:
// In = [0x01]
// Out = [0x01] [0x00] [0x00] [0x00] [0x00] [0x00] [0x00] [0x00]
void ByteToBit ( bool *Out, const char *In, int bits )
{
int i;
for ( i=0; i<bits; i++ )
{
// In[i]的第N位右移N位并和0x01按位"与"运算(N=1~8)
Out[i] = ( In[i/8]>> ( i%8 ) ) & 1;
}
}
void BitToByte ( char *Out, const bool *In, int bits )
{
int i;
memset ( Out, 0, ( bits+7 ) /8 );
for ( i=0; i<bits; i++ )
{
Out[i/8] |= In[i]<< ( i%8 );
}
}
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