HelenOS sources
This source file includes following definitions.
- sub_byte
- sub_bytes
- shift_rows
- inv_shift_rows
- galois_mult
- mix_columns
- inv_mix_columns
- add_round_key
- sub_word
- rot_word
- key_expansion
- aes_encrypt
- aes_decrypt
#include <stdbool.h>
#include <errno.h>
#include <mem.h>
#include "crypto.h"
#define ELEMS 4
#define CIPHER_ELEMS 4
#define BLOCK_LEN 16
#define ROUNDS 10
#define AES_IP 0x1b
static const uint8_t sbox[BLOCK_LEN][BLOCK_LEN] = {
{
0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5,
0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76
},
{
0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0,
0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0
},
{
0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc,
0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15
},
{
0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a,
0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75
},
{
0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0,
0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84
},
{
0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b,
0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf
},
{
0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85,
0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8
},
{
0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5,
0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2
},
{
0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17,
0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73
},
{
0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88,
0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb
},
{
0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c,
0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79
},
{
0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9,
0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08
},
{
0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6,
0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a
},
{
0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e,
0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e
},
{
0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94,
0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf
},
{
0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68,
0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16
}
};
static uint8_t inv_sbox[BLOCK_LEN][BLOCK_LEN] = {
{
0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38,
0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb
},
{
0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87,
0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb
},
{
0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d,
0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e
},
{
0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2,
0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25
},
{
0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16,
0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92
},
{
0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda,
0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84
},
{
0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a,
0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06
},
{
0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02,
0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b
},
{
0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea,
0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73
},
{
0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85,
0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e
},
{
0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89,
0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b
},
{
0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20,
0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4
},
{
0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31,
0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f
},
{
0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d,
0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef
},
{
0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0,
0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61
},
{
0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26,
0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d
}
};
static const uint32_t r_con_array[] = {
0x01000000, 0x02000000, 0x04000000, 0x08000000,
0x10000000, 0x20000000, 0x40000000, 0x80000000,
0x1b000000, 0x36000000
};
static uint8_t sub_byte(uint8_t byte, bool inv)
{
uint8_t i = byte >> 4;
uint8_t j = byte & 0xF;
if (!inv)
return sbox[i][j];
return inv_sbox[i][j];
}
static void sub_bytes(uint8_t state[ELEMS][ELEMS], bool inv)
{
uint8_t val;
for (size_t i = 0; i < ELEMS; i++) {
for (size_t j = 0; j < ELEMS; j++) {
val = state[i][j];
state[i][j] = sub_byte(val, inv);
}
}
}
static void shift_rows(uint8_t state[ELEMS][ELEMS])
{
uint8_t temp[ELEMS];
for (size_t i = 1; i < ELEMS; i++) {
memcpy(temp, state[i], i);
memmove(state[i], state[i] + i, ELEMS - i);
memcpy(state[i] + ELEMS - i, temp, i);
}
}
static void inv_shift_rows(uint8_t state[ELEMS][ELEMS])
{
uint8_t temp[ELEMS];
for (size_t i = 1; i < ELEMS; i++) {
memcpy(temp, state[i], ELEMS - i);
memmove(state[i], state[i] + ELEMS - i, i);
memcpy(state[i] + i, temp, ELEMS - i);
}
}
static uint8_t galois_mult(uint8_t x, uint8_t y)
{
uint8_t result = 0;
uint8_t f_bith;
for (size_t i = 0; i < 8; i++) {
if (y & 1)
result ^= x;
f_bith = (x & 0x80);
x <<= 1;
if (f_bith)
x ^= AES_IP;
y >>= 1;
}
return result;
}
static void mix_columns(uint8_t state[ELEMS][ELEMS])
{
uint8_t orig_state[ELEMS][ELEMS];
memcpy(orig_state, state, BLOCK_LEN);
for (size_t j = 0; j < ELEMS; j++) {
state[0][j] =
galois_mult(0x2, orig_state[0][j]) ^
galois_mult(0x3, orig_state[1][j]) ^
orig_state[2][j] ^
orig_state[3][j];
state[1][j] =
orig_state[0][j] ^
galois_mult(0x2, orig_state[1][j]) ^
galois_mult(0x3, orig_state[2][j]) ^
orig_state[3][j];
state[2][j] =
orig_state[0][j] ^
orig_state[1][j] ^
galois_mult(0x2, orig_state[2][j]) ^
galois_mult(0x3, orig_state[3][j]);
state[3][j] =
galois_mult(0x3, orig_state[0][j]) ^
orig_state[1][j] ^
orig_state[2][j] ^
galois_mult(0x2, orig_state[3][j]);
}
}
static void inv_mix_columns(uint8_t state[ELEMS][ELEMS])
{
uint8_t orig_state[ELEMS][ELEMS];
memcpy(orig_state, state, BLOCK_LEN);
for (size_t j = 0; j < ELEMS; j++) {
state[0][j] =
galois_mult(0x0e, orig_state[0][j]) ^
galois_mult(0x0b, orig_state[1][j]) ^
galois_mult(0x0d, orig_state[2][j]) ^
galois_mult(0x09, orig_state[3][j]);
state[1][j] =
galois_mult(0x09, orig_state[0][j]) ^
galois_mult(0x0e, orig_state[1][j]) ^
galois_mult(0x0b, orig_state[2][j]) ^
galois_mult(0x0d, orig_state[3][j]);
state[2][j] =
galois_mult(0x0d, orig_state[0][j]) ^
galois_mult(0x09, orig_state[1][j]) ^
galois_mult(0x0e, orig_state[2][j]) ^
galois_mult(0x0b, orig_state[3][j]);
state[3][j] =
galois_mult(0x0b, orig_state[0][j]) ^
galois_mult(0x0d, orig_state[1][j]) ^
galois_mult(0x09, orig_state[2][j]) ^
galois_mult(0x0e, orig_state[3][j]);
}
}
static void add_round_key(uint8_t state[ELEMS][ELEMS], uint32_t *round_key)
{
uint8_t byte_round;
uint8_t shift;
uint32_t mask = 0xff;
for (size_t j = 0; j < ELEMS; j++) {
for (size_t i = 0; i < ELEMS; i++) {
shift = 24 - 8 * i;
byte_round = (round_key[j] & (mask << shift)) >> shift;
state[i][j] = state[i][j] ^ byte_round;
}
}
}
static uint32_t sub_word(uint32_t word)
{
uint32_t temp = word;
uint8_t *start = (uint8_t *) &temp;
for (size_t i = 0; i < 4; i++)
*(start + i) = sub_byte(*(start + i), false);
return temp;
}
static uint32_t rot_word(uint32_t word)
{
return (word << 8 | word >> 24);
}
static void key_expansion(uint8_t *key, uint32_t *key_exp)
{
uint32_t temp;
for (size_t i = 0; i < CIPHER_ELEMS; i++) {
key_exp[i] =
(key[4 * i] << 24) +
(key[4 * i + 1] << 16) +
(key[4 * i + 2] << 8) +
(key[4 * i + 3]);
}
for (size_t i = CIPHER_ELEMS; i < ELEMS * (ROUNDS + 1); i++) {
temp = key_exp[i - 1];
if ((i % CIPHER_ELEMS) == 0) {
temp = sub_word(rot_word(temp)) ^
r_con_array[i / CIPHER_ELEMS - 1];
}
key_exp[i] = key_exp[i - CIPHER_ELEMS] ^ temp;
}
}
errno_t aes_encrypt(uint8_t *key, uint8_t *input, uint8_t *output)
{
if ((!key) || (!input))
return EINVAL;
if (!output)
return ENOMEM;
uint32_t key_exp[ELEMS * (ROUNDS + 1)];
key_expansion(key, key_exp);
uint8_t state[ELEMS][ELEMS];
for (size_t i = 0; i < ELEMS; i++) {
for (size_t j = 0; j < ELEMS; j++)
state[i][j] = input[i + ELEMS * j];
}
add_round_key(state, key_exp);
for (size_t k = 1; k <= ROUNDS; k++) {
sub_bytes(state, false);
shift_rows(state);
if (k < ROUNDS)
mix_columns(state);
add_round_key(state, key_exp + k * ELEMS);
}
for (size_t i = 0; i < ELEMS; i++) {
for (size_t j = 0; j < ELEMS; j++)
output[i + j * ELEMS] = state[i][j];
}
return EOK;
}
errno_t aes_decrypt(uint8_t *key, uint8_t *input, uint8_t *output)
{
if ((!key) || (!input))
return EINVAL;
if (!output)
return ENOMEM;
uint32_t key_exp[ELEMS * (ROUNDS + 1)];
key_expansion(key, key_exp);
uint8_t state[ELEMS][ELEMS];
for (size_t i = 0; i < ELEMS; i++) {
for (size_t j = 0; j < ELEMS; j++)
state[i][j] = input[i + ELEMS * j];
}
add_round_key(state, key_exp + ROUNDS * ELEMS);
for (int k = ROUNDS - 1; k >= 0; k--) {
inv_shift_rows(state);
sub_bytes(state, true);
add_round_key(state, key_exp + k * ELEMS);
if (k > 0)
inv_mix_columns(state);
}
for (size_t i = 0; i < ELEMS; i++) {
for (size_t j = 0; j < ELEMS; j++)
output[i + j * ELEMS] = state[i][j];
}
return EOK;
}
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