des.c

des加密算法 des加密算法 des加密算法 解密

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

typedef signed char bool;
static bool SubKey[16][48];
typedef enum {ENCRYPT, DECRYPT}
    Operation;

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
};
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
};
const 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
};
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
};
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
};

const static char LOOP_Table[16]=
{
    1, 1, 2, 2, 2, 2, 2, 2,
    1, 2, 2, 2, 2, 2, 2, 1
};
const static char S_Box[8][4][16]=
{
    {
        {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}
    },
    {
        {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}
    },
    {
        {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}
    },
    {
        {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}
    },
    {
        {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}
    },
    {
        {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}
    },
    {
        {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}
    },
    {
        {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}
    }
};
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]);
void DES_Cipher(char Out[8], char In[8], Operation Type);
void F_func(bool In[32], const bool Ki[48]);
void S_func(bool Out[32], const bool In[48]);
void Transform(bool *Out, bool *In, const char *Table, int len);
void Xor(bool *InA, const bool *InB, int len);
void RotateL(bool *In, int len, int loop);
void ByteToBit(bool *Out, const char *In, int bits);
void BitToByte(char *Out, const bool *In, int bits);

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);
    for(i=0; i<16; i++)
    {
        RotateL(KL, 28, LOOP_Table[i]);
        RotateL(KR, 28, LOOP_Table[i]);
        Transform(SubKey[i],K,PC2_Table,48);
    }
}
void DES_Cipher(char Out[8], char In[8], Operation Type)
{
    int i;
    static bool M[64], tmp[32], *Li = &M[0], *Ri = &M[32];
    ByteToBit(M, In, 64);
    Transform(M, M, IP_Table, 64);
    if(Type==ENCRYPT)
        for(i=0; i<16; i++)
        {
            memcpy(tmp, Ri, 32);
            F_func(Ri, SubKey[i]);
            Xor(Ri, Li, 32);
            memcpy(Li, tmp, 32);
        }
    if(Type==DECRYPT)
        for(i=15; i>=0; i--)
        {
            memcpy(tmp, Li, 32);
            F_func(Li, SubKey[i]);
            Xor(Li, Ri, 32);
            memcpy(Ri, tmp, 32);
        }
    Transform(M, M, IPR_Table, 64);
    BitToByte(Out, M, 64);
}
void F_func(bool In[32], const bool Ki[48])
{
    static bool MR[48];
    Transform(MR, In, E_Table, 48);
    Xor(MR, Ki, 48);
    S_func(In, MR);
    Transform(In, In, P_Table, 32);
}
void S_func(bool Out[32], const bool In[48])
{
    char j,m,n;
    for(j=0; j<8; j++,In+=6,Out+=4)
    {
        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);
    }
}
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];
    memcpy(tmp, In, loop);
    memcpy(In, In+loop, len-loop);
    memcpy(In+len-loop, tmp, loop);
}
void ByteToBit(bool *Out, const char *In, int bits)
{
    int i;
    for(i=0; i<bits; i++)
        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);
}

int main()
{
    char i,ch,key[8],plaintext[9],ciphertext[9];
    memset(key,0,sizeof(key));
    printf("Input Key: ");
    for(i=0;i<16;i++)
    {
        while((ch=getchar()),ch<'0' || ch>'9'&&ch<'A' || ch>'F');
        key[i/2]+=(ch-(ch<='9'?'0':'A'+10))*(i%2?1:16);
    }
    while(getchar()!='\n');
    DES_SetKey(key);
    printf("Input PlainText: ");
    gets(plaintext);
    memset(ciphertext,0,sizeof(ciphertext));
    DES_Cipher(ciphertext,plaintext,ENCRYPT);
    printf("CipherText: ");
    for(i=0;i<8;i++)
        printf("%02X",(unsigned char)ciphertext[i]);
    putchar('\n');
    memset(plaintext,0,sizeof(plaintext));
    DES_Cipher(plaintext,ciphertext,DECRYPT);
    printf("Decryption: ");
    puts(plaintext);
    return 0;
}