1#include <stdint.h>
2#include <stdlib.h>
3#include <unistd.h>
4
5struct expanded_key {
6    uint32_t l[16], r[16];
7};
8
9void __des_setkey(const unsigned char* key, struct expanded_key* ekey);
10void __do_des(uint32_t l_in, uint32_t r_in, uint32_t* l_out, uint32_t* r_out, uint32_t count,
11              uint32_t saltbits, const struct expanded_key* ekey);
12
13static struct expanded_key __encrypt_key;
14
15void setkey(const char* key) {
16    unsigned char bkey[8];
17    int i, j;
18
19    for (i = 0; i < 8; i++) {
20        bkey[i] = 0;
21        for (j = 7; j >= 0; j--, key++)
22            bkey[i] |= (uint32_t)(*key & 1) << j;
23    }
24
25    __des_setkey(bkey, &__encrypt_key);
26}
27
28void encrypt(char* block, int edflag) {
29    struct expanded_key decrypt_key, *key;
30    uint32_t b[2];
31    int i, j;
32    char* p;
33
34    p = block;
35    for (i = 0; i < 2; i++) {
36        b[i] = 0;
37        for (j = 31; j >= 0; j--, p++)
38            b[i] |= (uint32_t)(*p & 1) << j;
39    }
40
41    key = &__encrypt_key;
42    if (edflag) {
43        key = &decrypt_key;
44        for (i = 0; i < 16; i++) {
45            decrypt_key.l[i] = __encrypt_key.l[15 - i];
46            decrypt_key.r[i] = __encrypt_key.r[15 - i];
47        }
48    }
49
50    __do_des(b[0], b[1], b, b + 1, 1, 0, key);
51
52    p = block;
53    for (i = 0; i < 2; i++)
54        for (j = 31; j >= 0; j--)
55            *p++ = b[i] >> j & 1;
56}
57