mhibio
Des-Encryption.c
Code with poor quality. Please understand.
Only 8 bytes can be encrypted.
Operational modes such as ecb and cbc will be implemented later.
I referred to the box tables at https://dreamhack.io.
Des-Encryption.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#define BUF_SIZE 10
uint64_t bitarray2integer(char bitarray[], int leng);
void key_generation(char result[][48], char bitarray[]);
void char2bitarray(char bitarray[], char *buf);
void ROL_ARRAY(char array[], unsigned int rotation, int size);
void permutation(char result[], char bitarray[], const char table[], int leng);
void bitdump(char bitarray[], int leng);
char *round_f(char result[], char bitarray[], char roundkey[]);
const char IPT[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 char FPT[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
};
// Expansion P-Box Table
const char EPT[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
};
// S-Boxs
const char SBOX[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},
}
};
// Straight P-Box Table
const char SPT[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
};
// Parity Bit Drop Table
const char PBDT[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
};
// Compression P-Box Table
const char CPBT[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
};
// 1, 2, 9, 16 => ROL(1)
// else => ROL(2)
const char shifting[16] = { 1 ,1 ,2 ,2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1 };
void permutation(char result[], char bitarray[], const char table[], int length) {
for(int i = 0; i < length; i++) {
result[i] = bitarray[table[i]-1];
}
}
void key_generation(char result[][48], char bitarray[]) {
char pc1_result[56] = {0, };
char concat[48] = {0, };
char left[28], right[28];
// Parity Drop and Permutation
permutation(pc1_result, bitarray, PBDT, 56);
for(int n1 = 0; n1 < 28; n1++) left[n1] = pc1_result[n1];
for(int n2 = 28; n2 < 56; n2++) right[n2-28] = pc1_result[n2];
for(int i = 0; i < 16; i++) {
ROL_ARRAY(left, shifting[i], 28);
ROL_ARRAY(right, shifting[i], 28);
for(int n1 = 0; n1 < 28; n1++) {
concat[n1] = left[n1];
concat[n1+28] = right[n1];
}
// Compression P-box
permutation(result[i], concat, CPBT, 48);
}
}
uint64_t bitarray2integer(char bitarray[], int leng) {
uint64_t result = 0;
for(int i = 0; i < leng; i++)
result |= ( (uint64_t)bitarray[i] << (leng-i-1) );
return result;
}
void char2bitarray(char bitarray[], char *buf) {
for(int i = 0; i < 64; i++) {
bitarray[(8 * (i/8)) + 7-(i % 8)] = (buf[i / 8] & (1 << (i % 8))) >> (i % 8);
}
}
void bitdump(char bitarray[], int leng) {
printf("[+] BITDUMP : ");
for(int i = 0; i < leng; i++)
printf("%d", bitarray[i]);
printf("\n");
}
void ROL_ARRAY(char array[], unsigned int rotation, int size) {
char tmp = 0;
for(int i = 0; i < rotation; i++) {
tmp = array[0];
for(int j = 0; j < size-1; j++)
array[j] = array[j+1];
array[size-1] = tmp;
}
}
char* round_f(char result[], char bitarray[], char roundkey[]) {
char extend_bitarray[48] = {0, };
char temp_bitarray[32] = {0, };
char sbox_calc[6] = {0, };
char row, col, val;
permutation(extend_bitarray, bitarray, EPT, 48);
for(int i = 0; i < 48; i++)
extend_bitarray[i] ^= roundkey[i];
for(int i = 0; i < 8; i++) {
memcpy(sbox_calc, &extend_bitarray[i*6], 6);
row = (sbox_calc[0] << 1) + sbox_calc[5];
col = (sbox_calc[1] << 3) + (sbox_calc[2] << 2) + (sbox_calc[3] << 1) + sbox_calc[4];
val = SBOX[i][row][col];
for(int j = 0; j < 4; j++)
temp_bitarray[i*4 + j] = (val >> (3-j)) & 1;
}
permutation(result, temp_bitarray, SPT, 32);
}
int main() {
char *buf = malloc(BUF_SIZE);
char *key = malloc(BUF_SIZE);
char left[32], right[32], tmp[32], round_result[32];
char buf_bitarray[64] = {0, };
char key_bitarray[64] = {0, };
char ip_array[64] = {0, };
char result[64] = {0, };
char round_key[16][48] = {0, };
printf("Input Message ( 8 Bytes ): ");
fgets(buf, BUF_SIZE, stdin);
buf[strlen(buf) - 1] = '\0';
char2bitarray(buf_bitarray, buf);
printf("Input Key ( 8 Bytes ): ");
fgets(key, BUF_SIZE, stdin);
key[strlen(key) - 1] = '\0';
char2bitarray(key_bitarray, key);
// initial permutation
permutation(ip_array, buf_bitarray, IPT, 64);
key_generation(round_key, key_bitarray);
memcpy(left, ip_array, 32);
memcpy(right, &ip_array[32], 32);
for(int i = 0; i < 16; i++) {
round_f(round_result, right, round_key[i]);
for(int n = 0; n < 32; n++) {
left[n] ^= round_result[n];
}
memcpy(tmp, left, 32);
memcpy(left, right, 32);
memcpy(right, tmp, 32);
}
memcpy(ip_array, right, 32);
memcpy(&ip_array[32], left, 32);
// final permutation
permutation(result, ip_array, FPT, 64);
printf("Encrypted : %lu\n", bitarray2integer(result, 64));
printf("hex(Encrypted) : %lx", bitarray2integer(result, 64));
return 0;
}
To improve algorithm skills and coding skills, I will implement several Encryption scheme, such as aes, in c.
Also, optimizing these codes is one of the goals.