📄 des.cpp
字号:
＃i nclude <stdlib.h>
＃i nclude <stdio.h>
#define ENCRYPT 1
#define DECRYPT 0
typedef char bool;
// 16 sub keys
static bool SubKey[16][48];
// Permuted Choice 1 (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
};
// Left Shifts
const static char LOOP_Table[16] =
{
1, 1, 2, 2, 2, 2, 2, 2,
1, 2, 2, 2, 2, 2, 2, 1
};
// Permuted Choice 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
};
// Initial Permutation (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
};
// Expansion (E)
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
};
// The (in)famous 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}
}
};
// Permutation 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
};
// Final Permutation (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
};
// 主函数
void Des_SetKey(const char Key[8]);
void Des_Run(char Out[8], char In[8], bool Type);
// 功能函数
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
// 测试用
static void printHex( char *cmd, int len );
static void printArray( const char *In, int len );
int main(int argc, char *argv[])
{
char key[12]={1,2,3,4,5,6,7,8};
char str[12]="YOKO LA!";
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);
return 0;
}
// == 1. Process the key ==
void Des_SetKey(const char Key[8])
{
int i;
static bool K[64], *KL = &K[0], *KR = &K[28];
ByteToBit(K, Key, 64);
Transform(K, K, PC1_Table, 56);
// 1.2.3 Calculate the 16 sub keys. Start with i = 1.
for(i=0; i<16; i++)
{
// 1.2.3.1 Perform one or two circular left shifts on both C[i-1] and D[i-1] to get C[i] and D[i], respectively.
RotateL(KL, 28, LOOP_Table[i]);
RotateL(KR, 28, LOOP_Table[i]);
// 1.2.3.2 Permute the concatenation C[i]D[i] as indicated below. This will yield K[i], which is 48 bits long.
Transform(SubKey[i], K, PC2_Table, 48);
}
}
// == 2. Process a 64-bit data block ==
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];
// 2.1 Get a 64-bit data block. If the block is shorter than 64 bits, it should be padded as appropriate for the application.
ByteToBit(M, In, 64);
// 2.2 Perform the following permutation on the data block.
Transform(M, M, IP_Table, 64);
//2.3 Split the block into two halves. The first 32 bits are called L[0], and the last 32 bits are called R[0].
if( Type == ENCRYPT )
{
// 2.4 Apply the 16 sub keys to the data block. Start with i = 1.
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);
} //2.4.8 Loop back to 2.4.1 until K[16] has been applied.
}
else
{
// To decrypt, use the same process
// but just use the keys K[i] in reverse order
for(i=15; i>=0; i--)
{
memcpy(tmp, Li, 32);
F_func(Li, SubKey[i]);
Xor(Li, Ri, 32);
memcpy(Ri, tmp, 32);
}
}
// 2.5 Perform the following permutation on the block R[16]L[16]. (Note that block R precedes block L this time.)
Transform(M, M, IPR_Table, 64);
BitToByte(Out, M, 64);
}
void F_func(bool In[32], const bool Ki[48])
{
static bool MR[48];
// 2.4.1 Expand the 32-bit R[i-1] into 48 bits according to the bit-selection function below.
Transform(MR, In, E_Table, 48);
// 2.4.2 Exclusive-or E(R[i-1]) with K[i].
Xor(MR, Ki, 48);
// 2.4.4 Substitute the values found in the S-boxes for all B[j]. Start with j = 1. All values in the S-boxes should be considered 4 bits wide.
S_func(In, MR);
// 2.4.5 Permute the concatenation of B[1] through B[8] as indicated below.
Transform(In, In, P_Table, 32);
}
void S_func(bool Out[32], const bool In[48])
{
char j,m,n;
//2.4.3 Break E(R[i-1]) xor K[i] into eight 6-bit blocks. Bits 1-6 are B[1]...
for(j=0; j<8; j++,In+=6,Out+=4)
{
// 2.4.4.1 Take the 1st and 6th bits of B[j] together as a 2-bit value (call it m) indicating the row in S[j] to look in for the substitution.
m = (In[0]<<1) + In[5];
// 2.4.4.2 Take the 2nd through 5th bits of B[j] together as a 4-bit value (call it n) indicating the column in S[j] to find the substitution.
n = (In[1]<<3) + (In[2]<<2) + (In[3]<<1) + In[4];
// 2.4.4.3 Replace B[j] with S[j][m][n].
ByteToBit(Out, &S_Box[(int)j][(int)m][(int)n], 4);
}
}
// -- Perform the permutation --
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);
}
// -- xor --
void Xor(bool *InA, const bool *InB, int len)
{
int i;
for(i=0; i<len; i++)
{
InA[i] ^= InB[i];
}
}
// -- Perform one or two circular left shifts --
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);
}
}
// 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");
}
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