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blowfish.c
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blowfish.c
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#include <stdlib.h>
#include <string.h>
#include "blowfish.h"
#include "constants.h"
uint32_t
feistel_function(uint32_t arg)
{
uint32_t var = sbox[0][arg >> 24] + sbox[1][(uint8_t)(arg >> 16)];
return (var ^ sbox[2][(uint8_t)(arg >> 8)]) + sbox[3][(uint8_t)(arg)];
}
void
_encrypt(uint32_t *left, uint32_t *right)
{
uint32_t i, t;
for (i = 0; i < 16; i++) {
*left ^= pbox[i];
*right ^= feistel_function(*left);
SWAP(*left, *right, t);
}
SWAP(*left, *right, t);
*right ^= pbox[16];
*left ^= pbox[17];
}
void
_decrypt(uint32_t *left, uint32_t *right)
{
uint32_t i, t;
for (i = 17; i > 1; i--) {
*left ^= pbox[i];
*right ^= feistel_function(*left);
SWAP(*left, *right, t);
}
SWAP(*left, *right, t);
*right ^= pbox[1];
*left ^= pbox[0];
}
void
blowfish_init(uint8_t key[], int size)
{
int keysize = size, i, j;
uint32_t left = 0x00000000, right = 0x00000000;
/* subkey generation */
for (i = 0; i < 18; i++) {
pbox[i] ^= ((uint32_t)key[(i + 0) % keysize] << 24) |
((uint32_t)key[(i + 1) % keysize] << 16) |
((uint32_t)key[(i + 2) % keysize] << 8) |
((uint32_t)key[(i + 3) % keysize]);
}
/* encrypt the zeroes, modifying the p-array and s-boxes accordingly */
for (i = 0; i <= 17; i += 2) {
_encrypt(&left, &right);
pbox[i] = left;
pbox[i + 1] = right;
}
for (i = 0; i <= 3; i++) {
for (j = 0; j <= 254; j += 2) {
_encrypt(&left, &right);
sbox[i][j] = left;
sbox[i][j + 1] = right;
}
}
}
uint8_t *
blowfish_encrypt(uint8_t data[], int padsize)
{
uint8_t *encrypted = malloc(sizeof *encrypted * padsize);
uint8_t byte;
uint32_t i, j, index = 0;
uint32_t left, right, datasize, factor;
uint64_t chunk;
datasize = padsize;
for (i = 0; i < datasize; i += 8) {
/* make 8 byte chunks */
chunk = 0x0000000000000000;
memmove(&chunk, data + i, sizeof(chunk));
/* split into two 4 byte chunks */
left = right = 0x00000000;
left = (uint32_t)(chunk >> 32);
right = (uint32_t)(chunk);
_encrypt(&left, &right);
/* merge encrypted halves into a single 8 byte chunk again */
chunk = 0x0000000000000000;
chunk |= left; chunk <<= 32;
chunk |= right;
/* append the chunk into the answer */
memmove(encrypted + i, &chunk, sizeof(chunk));
}
return encrypted;
}
uint8_t *
blowfish_decrypt(uint8_t crypt_data[], int padsize)
{
uint8_t *decrypted = malloc(sizeof *decrypted * padsize);
uint8_t byte;
uint32_t i, j, index = 0;
uint32_t left, right, datasize, factor;
uint64_t chunk;
datasize = padsize;
for (i = 0; i < datasize; i += 8) {
chunk = 0x0000000000000000;
memmove(&chunk, crypt_data + i, sizeof(chunk));
left = right = 0x00000000;
left = (uint32_t)(chunk >> 32);
right = (uint32_t)(chunk);
_decrypt(&left, &right);
chunk = 0x0000000000000000;
chunk |= left; chunk <<= 32;
chunk |= right;
memmove(decrypted + i, &chunk, sizeof(chunk));
}
return decrypted;
}