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#include <stdint.h>
#include <string.h>
#include "cipher.h"
#include "parameters.h"
#include "tweakey.h"
enum permutation
{
PERMUTATION_ENCRYPTION = 0,
PERMUTATION_DECRYPTION = 1,
PERMUTATION_NONE
};
typedef enum permutation permutation;
static const uint8_t PERMUTATIONS[2][BLOCK_BYTES] = {
/* PI(i) */
[0] = { 13, 9, 14, 8, 10, 11, 12, 15,
4, 5, 3, 1, 2, 6, 0, 7 },
/* PI^-1(i) */
[1] = { 14, 11, 12, 10, 8, 9, 13, 15,
3, 1, 4, 5, 6, 0, 2, 7 }
};
static const uint8_t S[256] = {
32, 0, 178, 133, 59, 53, 166, 164,
48, 228, 106, 44, 255, 89, 226, 14,
248, 30, 122, 128, 21, 189, 62, 177,
232, 243, 162, 194, 218, 81, 42, 16,
33, 1, 35, 120, 92, 36, 39, 181,
55, 199, 43, 31, 174, 10, 119, 95,
111, 9, 157, 129, 4, 90, 41, 220,
57, 156, 5, 87, 151, 116, 121, 23,
68, 198, 230, 233, 221, 65, 242, 138,
84, 202, 110, 74, 225, 173, 182, 136,
28, 152, 126, 206, 99, 73, 58, 93,
12, 239, 246, 52, 86, 37, 46, 214,
103, 117, 85, 118, 184, 210, 97, 217,
113, 139, 205, 11, 114, 108, 49, 75,
105, 253, 123, 109, 96, 60, 47, 98,
63, 34, 115, 19, 201, 130, 127, 83,
50, 18, 160, 124, 2, 135, 132, 134,
147, 78, 104, 70, 141, 195, 219, 236,
155, 183, 137, 146, 167, 190, 61, 216,
234, 80, 145, 241, 51, 56, 224, 169,
163, 131, 161, 27, 207, 6, 149, 7,
158, 237, 185, 245, 76, 192, 244, 45,
22, 250, 180, 3, 38, 179, 144, 79,
171, 101, 252, 254, 20, 247, 227, 148,
238, 172, 140, 26, 222, 203, 40, 64,
125, 200, 196, 72, 107, 223, 165, 82,
229, 251, 215, 100, 249, 240, 211, 94,
102, 150, 143, 29, 69, 54, 204, 197,
77, 159, 191, 15, 209, 8, 235, 67,
66, 25, 231, 153, 168, 142, 88, 193,
154, 212, 24, 71, 170, 175, 188, 91,
213, 17, 208, 176, 112, 187, 13, 186
};
static void _state_init(uint8_t X[BLOCK_BYTES], const uint8_t message[BLOCK_BYTES])
{
memcpy(X, message, BLOCK_BYTES);
}
static void _compute_round_tweakeys(
const uint8_t key[KEY_BYTES],
const uint8_t tweak[TWEAK_BYTES],
uint8_t RTK[ROUNDS][ROUND_TWEAKEY_BYTES]
)
{
uint8_t TK[TWEAKEY_BYTES];
tweakey_state_init(TK, key, tweak);
tweakey_state_extract(TK, 0, RTK[0]);
for (uint8_t i=1; i<ROUNDS; i++)
{
tweakey_state_update(TK);
tweakey_state_extract(TK, i, RTK[i]);
}
}
static void _nonlinear_layer(uint8_t X[BLOCK_BYTES], const uint8_t RTK[ROUND_TWEAKEY_BYTES])
{
uint8_t F[ROUND_TWEAKEY_BYTES];
for (size_t j=0; j<ROUND_TWEAKEY_BYTES; j++)
{
F[j] = X[j] ^ RTK[j];
}
for (size_t j=0; j<ROUND_TWEAKEY_BYTES; j++)
{
F[j] = S[F[j]];
}
for (size_t j=0; j<8; j++)
{
size_t dest_j = 15-j;
X[dest_j] ^= F[j];
}
}
static void _linear_layer(uint8_t X[BLOCK_BYTES])
{
X[15] ^= X[1];
X[15] ^= X[2];
X[15] ^= X[3];
X[15] ^= X[4];
X[15] ^= X[5];
X[15] ^= X[6];
X[15] ^= X[7];
X[14] ^= X[7];
X[13] ^= X[7];
X[12] ^= X[7];
X[11] ^= X[7];
X[10] ^= X[7];
X[9] ^= X[7];
}
static void _permutation_layer(uint8_t X[BLOCK_BYTES], permutation p)
{
if (p == PERMUTATION_NONE)
{
return;
}
uint8_t X_old[BLOCK_BYTES];
memcpy(X_old, X, BLOCK_BYTES);
const uint8_t *pi = PERMUTATIONS[p];
for (size_t j=0; j<BLOCK_BYTES; j++)
{
X[pi[j]] = X_old[j];
}
}
static void _one_round_egfn(uint8_t X[BLOCK_BYTES], const uint8_t RTK[ROUND_TWEAKEY_BYTES], permutation p)
{
_nonlinear_layer(X, RTK);
_linear_layer(X);
_permutation_layer(X, p);
}
void lilliput_tbc_encrypt(
const uint8_t key[KEY_BYTES],
const uint8_t tweak[TWEAK_BYTES],
const uint8_t message[BLOCK_BYTES],
uint8_t ciphertext[BLOCK_BYTES]
)
{
uint8_t X[BLOCK_BYTES];
_state_init(X, message);
uint8_t RTK[ROUNDS][ROUND_TWEAKEY_BYTES];
_compute_round_tweakeys(key, tweak, RTK);
for (uint8_t i=0; i<ROUNDS-1; i++)
{
_one_round_egfn(X, RTK[i], PERMUTATION_ENCRYPTION);
}
_one_round_egfn(X, RTK[ROUNDS-1], PERMUTATION_NONE);
memcpy(ciphertext, X, BLOCK_BYTES);
}
void lilliput_tbc_decrypt(
const uint8_t key[KEY_BYTES],
const uint8_t tweak[TWEAK_BYTES],
const uint8_t ciphertext[BLOCK_BYTES],
uint8_t message[BLOCK_BYTES]
)
{
uint8_t X[BLOCK_BYTES];
_state_init(X, ciphertext);
uint8_t RTK[ROUNDS][ROUND_TWEAKEY_BYTES];
_compute_round_tweakeys(key, tweak, RTK);
for (uint8_t i=0; i<ROUNDS-1; i++)
{
_one_round_egfn(X, RTK[ROUNDS-1-i], PERMUTATION_DECRYPTION);
}
_one_round_egfn(X, RTK[0], PERMUTATION_NONE);
memcpy(message, X, BLOCK_BYTES);
}
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