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btstack_crypto: change aes_cmac to access all message bytes sequentially

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This commit is contained in:
Matthias Ringwald 2020-01-09 22:18:13 +01:00
parent 7aa521df15
commit 8e361704e5
2 changed files with 53 additions and 52 deletions
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72
src/btstack_crypto.c
View File

@ -137,7 +137,7 @@ static uint8_t btstack_crypto_wait_for_hci_result;
static btstack_crypto_cmac_state_t btstack_crypto_cmac_state;
static sm_key_t btstack_crypto_cmac_k;
static sm_key_t btstack_crypto_cmac_x;
static sm_key_t btstack_crypto_cmac_m_last;
static sm_key_t btstack_crypto_cmac_subkey;
static uint8_t btstack_crypto_cmac_block_current;
static uint8_t btstack_crypto_cmac_block_count;
#endif
@ -215,6 +215,7 @@ static void btstack_crypto_cmac_calc_subkeys(sm_key_t k0, sm_key_t k1, sm_key_t
static void btstack_crypto_cmac_calc(btstack_crypto_aes128_cmac_t * btstack_crypto_cmac) {
sm_key_t k0, k1, k2;
uint16_t i;
btstack_aes128_calc(btstack_crypto_cmac->key, zero, k0);
btstack_crypto_cmac_calc_subkeys(k0, k1, k2);
@ -226,10 +227,22 @@ static void btstack_crypto_cmac_calc(btstack_crypto_aes128_cmac_t * btstack_cryp
cmac_block_count = 1;
}
// Step 5
sm_key_t cmac_x;
memset(cmac_x, 0, 16);
// Step 6
sm_key_t cmac_y;
for (int block = 0 ; block < cmac_block_count-1 ; block++){
for (i=0;i<16;i++){
cmac_y[i] = cmac_x[i] ^ btstack_crypto_cmac_get_byte(btstack_crypto_cmac, (block*16) + i);
}
btstack_aes128_calc(btstack_crypto_cmac->key, cmac_y, cmac_x);
}
// step 4: set m_last
sm_key_t cmac_m_last;
bool last_block_complete = btstack_crypto_cmac->size != 0 && (btstack_crypto_cmac->size & 0x0f) == 0;
uint16_t i;
if (last_block_complete){
for (i=0;i<16;i++){
cmac_m_last[i] = btstack_crypto_cmac_get_byte(btstack_crypto_cmac, btstack_crypto_cmac->size - 16 + i) ^ k1[i];
@ -249,18 +262,6 @@ static void btstack_crypto_cmac_calc(btstack_crypto_aes128_cmac_t * btstack_cryp
}
}
// Step 5
sm_key_t cmac_x;
memset(cmac_x, 0, 16);
// Step 6
sm_key_t cmac_y;
for (int block = 0 ; block < cmac_block_count-1 ; block++){
for (i=0;i<16;i++){
cmac_y[i] = cmac_x[i] ^ btstack_crypto_cmac_get_byte(btstack_crypto_cmac, (block*16) + i);
}
btstack_aes128_calc(btstack_crypto_cmac->key, cmac_y, cmac_x);
}
for (i=0;i<16;i++){
cmac_y[i] = cmac_x[i] ^ cmac_m_last[i];
}
@ -308,29 +309,10 @@ static void btstack_crypto_cmac_handle_aes_engine_ready(btstack_crypto_aes128_cm
break;
}
case CMAC_CALC_MLAST: {
int i;
sm_key_t y;
for (i=0;i<16;i++){
y[i] = btstack_crypto_cmac_x[i] ^ btstack_crypto_cmac_m_last[i];
}
btstack_crypto_cmac_block_current++;
btstack_crypto_cmac_next_state();
btstack_crypto_aes128_start(btstack_crypto_cmac_k, y);
break;
}
default:
log_info("btstack_crypto_cmac_handle_aes_engine_ready called in state %u", btstack_crypto_cmac_state);
break;
}
}
static void btstack_crypto_cmac_handle_encryption_result(btstack_crypto_aes128_cmac_t * btstack_crypto_cmac, sm_key_t data){
switch (btstack_crypto_cmac_state){
case CMAC_W4_SUBKEYS: {
sm_key_t k1;
(void)memcpy(k1, data, 16);
(void)memcpy(k1, btstack_crypto_cmac_subkey, 16);
btstack_crypto_cmac_shift_left_by_one_bit_inplace(16, k1);
if (data[0] & 0x80){
if (btstack_crypto_cmac_subkey[0] & 0x80){
k1[15] ^= 0x87;
}
sm_key_t k2;
@ -346,6 +328,7 @@ static void btstack_crypto_cmac_handle_encryption_result(btstack_crypto_aes128_c
// step 4: set m_last
int i;
sm_key_t btstack_crypto_cmac_m_last;
if (btstack_crypto_cmac_last_block_complete(btstack_crypto_cmac)){
for (i=0;i<16;i++){
btstack_crypto_cmac_m_last[i] = btstack_crypto_cmac_get_byte(btstack_crypto_cmac, btstack_crypto_cmac->size - 16 + i) ^ k1[i];
@ -364,11 +347,28 @@ static void btstack_crypto_cmac_handle_encryption_result(btstack_crypto_aes128_c
btstack_crypto_cmac_m_last[i] = k2[i];
}
}
sm_key_t y;
for (i=0;i<16;i++){
y[i] = btstack_crypto_cmac_x[i] ^ btstack_crypto_cmac_m_last[i];
}
btstack_crypto_cmac_block_current++;
btstack_crypto_cmac_next_state();
btstack_crypto_aes128_start(btstack_crypto_cmac_k, y);
break;
}
default:
log_info("btstack_crypto_cmac_handle_aes_engine_ready called in state %u", btstack_crypto_cmac_state);
break;
}
}
static void btstack_crypto_cmac_handle_encryption_result(btstack_crypto_aes128_cmac_t * btstack_crypto_cmac, sm_key_t data){
switch (btstack_crypto_cmac_state){
case CMAC_W4_SUBKEYS:
(void)memcpy(btstack_crypto_cmac_subkey, data, 16);
// next
btstack_crypto_cmac_state = (btstack_crypto_cmac_block_current < (btstack_crypto_cmac_block_count - 1)) ? CMAC_CALC_MI : CMAC_CALC_MLAST;
break;
}
case CMAC_W4_MI:
(void)memcpy(btstack_crypto_cmac_x, data, 16);
btstack_crypto_cmac_state = (btstack_crypto_cmac_block_current < (btstack_crypto_cmac_block_count - 1)) ? CMAC_CALC_MI : CMAC_CALC_MLAST;

33
test/crypto/aes_cmac.c
View File

@ -33,6 +33,7 @@ void aes_cmac_calc_subkeys(sm_key_t k0, sm_key_t k1, sm_key_t k2){
}
void aes_cmac(sm_key_t aes_cmac, const sm_key_t key, const uint8_t * data, int sm_cmac_message_len){
unsigned int i;
sm_key_t k0, k1, k2, zero;
memset(zero, 0, 16);
@ -46,10 +47,25 @@ void aes_cmac(sm_key_t aes_cmac, const sm_key_t key, const uint8_t * data, int s
sm_cmac_block_count = 1;
}
// printf("sm_cmac_start: len %u, block count %u\n", sm_cmac_message_len, sm_cmac_block_count);
// LOG_KEY(sm_cmac_m_last);
// Step 5
sm_key_t sm_cmac_x;
memset(sm_cmac_x, 0, 16);
// Step 6
sm_key_t sm_cmac_y;
for (int block = 0 ; block < sm_cmac_block_count-1 ; block++){
for (i=0;i<16;i++){
sm_cmac_y[i] = sm_cmac_x[i] ^ data[block * 16 + i];
}
aes128_calc_cyphertext(key, sm_cmac_y, sm_cmac_x);
}
// step 4: set m_last
sm_key_t sm_cmac_m_last;
int sm_cmac_last_block_complete = sm_cmac_message_len != 0 && (sm_cmac_message_len & 0x0f) == 0;
int i;
if (sm_cmac_last_block_complete){
for (i=0;i<16;i++){
sm_cmac_m_last[i] = data[sm_cmac_message_len - 16 + i] ^ k1[i];
@ -69,21 +85,6 @@ void aes_cmac(sm_key_t aes_cmac, const sm_key_t key, const uint8_t * data, int s
}
}
// printf("sm_cmac_start: len %u, block count %u\n", sm_cmac_message_len, sm_cmac_block_count);
// LOG_KEY(sm_cmac_m_last);
// Step 5
sm_key_t sm_cmac_x;
memset(sm_cmac_x, 0, 16);
// Step 6
sm_key_t sm_cmac_y;
for (int block = 0 ; block < sm_cmac_block_count-1 ; block++){
for (i=0;i<16;i++){
sm_cmac_y[i] = sm_cmac_x[i] ^ data[block * 16 + i];
}
aes128_calc_cyphertext(key, sm_cmac_y, sm_cmac_x);
}
for (i=0;i<16;i++){
sm_cmac_y[i] = sm_cmac_x[i] ^ sm_cmac_m_last[i];
}