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btstack_crypto: use software aes128 for cmac message [a2473]

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This commit is contained in:
Matthias Ringwald 2019-12-08 21:15:21 +01:00
parent cfbd0db491
commit d8fc648c51
2 changed files with 116 additions and 25 deletions
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138
src/btstack_crypto.c
View File

@ -178,6 +178,98 @@ static void btstack_crypto_done(btstack_crypto_t * btstack_crypto){
(*btstack_crypto->context_callback.callback)(btstack_crypto->context_callback.context);
}
static void btstack_crypto_cmac_shift_left_by_one_bit_inplace(int len, uint8_t * data){
int i;
int carry = 0;
for (i=len-1; i >= 0 ; i--){
int new_carry = data[i] >> 7;
data[i] = (data[i] << 1) | carry;
carry = new_carry;
}
}
#ifdef USE_BTSTACK_AES128
static void btstack_crypto_cmac_calc_subkeys(sm_key_t k0, sm_key_t k1, sm_key_t k2){
memcpy(k1, k0, 16);
btstack_crypto_cmac_shift_left_by_one_bit_inplace(16, k1);
if (k0[0] & 0x80){
k1[15] ^= 0x87;
}
memcpy(k2, k1, 16);
btstack_crypto_cmac_shift_left_by_one_bit_inplace(16, k2);
if (k1[0] & 0x80){
k2[15] ^= 0x87;
}
}
static void btstack_crypto_cmac_calc(btstack_crypto_aes128_cmac_t * btstack_crypto_cmac) {
sm_key_t k0, k1, k2;
btstack_aes128_calc(btstack_crypto_cmac->key, zero, k0);
btstack_crypto_cmac_calc_subkeys(k0, k1, k2);
uint16_t cmac_block_count = (btstack_crypto_cmac->size + 15) / 16;
// step 3: ..
if (cmac_block_count==0){
cmac_block_count = 1;
}
// 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->data.message[btstack_crypto_cmac->size - 16 + i] ^ k1[i];
}
} else {
uint16_t valid_octets_in_last_block = btstack_crypto_cmac->size & 0x0f;
for (i=0;i<16;i++){
if (i < valid_octets_in_last_block){
cmac_m_last[i] = btstack_crypto_cmac->data.message[(btstack_crypto_cmac->size & 0xfff0) + i] ^ k2[i];
continue;
}
if (i == valid_octets_in_last_block){
cmac_m_last[i] = 0x80 ^ k2[i];
continue;
}
cmac_m_last[i] = k2[i];
}
}
// 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->data.message[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];
}
// Step 7
btstack_aes128_calc(btstack_crypto_cmac->key, cmac_y, btstack_crypto_cmac->hash);
}
#else
static void btstack_crypto_aes128_start(const sm_key_t key, const sm_key_t plaintext){
uint8_t key_flipped[16];
uint8_t plaintext_flipped[16];
reverse_128(key, key_flipped);
reverse_128(plaintext, plaintext_flipped);
btstack_crypto_wait_for_hci_result = 1;
hci_send_cmd(&hci_le_encrypt, key_flipped, plaintext_flipped);
}
static inline void btstack_crypto_cmac_next_state(void){
btstack_crypto_cmac_state = (btstack_crypto_cmac_state_t) (((int)btstack_crypto_cmac_state) + 1);
}
@ -188,15 +280,6 @@ static int btstack_crypto_cmac_last_block_complete(btstack_crypto_aes128_cmac_t
return (len & 0x0f) == 0;
}
static void btstack_crypto_aes128_start(const sm_key_t key, const sm_key_t plaintext){
uint8_t key_flipped[16];
uint8_t plaintext_flipped[16];
reverse_128(key, key_flipped);
reverse_128(plaintext, plaintext_flipped);
btstack_crypto_wait_for_hci_result = 1;
hci_send_cmd(&hci_le_encrypt, key_flipped, plaintext_flipped);
}
static uint8_t btstack_crypto_cmac_get_byte(btstack_crypto_aes128_cmac_t * btstack_crypto_cmac, uint16_t pos){
if (btstack_crypto_cmac->btstack_crypto.operation == BTSTACK_CRYPTO_CMAC_GENERATOR){
return (*btstack_crypto_cmac->data.get_byte_callback)(pos);
@ -208,10 +291,8 @@ static uint8_t btstack_crypto_cmac_get_byte(btstack_crypto_aes128_cmac_t * btsta
static void btstack_crypto_cmac_handle_aes_engine_ready(btstack_crypto_aes128_cmac_t * btstack_crypto_cmac){
switch (btstack_crypto_cmac_state){
case CMAC_CALC_SUBKEYS: {
sm_key_t const_zero;
memset(const_zero, 0, 16);
btstack_crypto_cmac_next_state();
btstack_crypto_aes128_start(btstack_crypto_cmac_k, const_zero);
btstack_crypto_aes128_start(btstack_crypto_cmac_k, zero);
break;
}
case CMAC_CALC_MI: {
@ -242,16 +323,6 @@ static void btstack_crypto_cmac_handle_aes_engine_ready(btstack_crypto_aes128_cm
}
}
static void btstack_crypto_cmac_shift_left_by_one_bit_inplace(int len, uint8_t * data){
int i;
int carry = 0;
for (i=len-1; i >= 0 ; i--){
int new_carry = data[i] >> 7;
data[i] = (data[i] << 1) | carry;
carry = new_carry;
}
}
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: {
@ -337,6 +408,7 @@ static void btstack_crypto_cmac_start(btstack_crypto_aes128_cmac_t * btstack_cry
// let's go
btstack_crypto_cmac_handle_aes_engine_ready(btstack_crypto_cmac);
}
#endif
#ifndef USE_BTSTACK_AES128
@ -576,7 +648,6 @@ static void btstack_crypto_ccm_calc_xn(btstack_crypto_ccm_t * btstack_crypto_ccm
btstack_crypto_aes128_start(btstack_crypto_ccm->key, btstack_crypto_ccm_buffer);
}
#endif
static void btstack_crypto_ccm_calc_aad_xn(btstack_crypto_ccm_t * btstack_crypto_ccm){
// store length
@ -659,6 +730,7 @@ static void btstack_crypto_ccm_next_block(btstack_crypto_ccm_t * btstack_crypto_
}
}
}
#endif
static void btstack_crypto_run(void){
@ -700,15 +772,29 @@ static void btstack_crypto_run(void){
btstack_crypto_aes128_start(btstack_crypto_aes128->key, btstack_crypto_aes128->plaintext);
#endif
break;
#ifdef USE_BTSTACK_AES128
case BTSTACK_CRYPTO_CMAC_MESSAGE:
btstack_crypto_cmac = (btstack_crypto_aes128_cmac_t *) btstack_crypto;
btstack_crypto_cmac_calc( btstack_crypto_cmac );
btstack_crypto_done(btstack_crypto);
break;
case BTSTACK_CRYPTO_CMAC_GENERATOR:
UNUSED(btstack_crypto_cmac);
// NOTE: infinite output of this message
log_error("cmac with not implemented for software aes128 yet");
break;
#else
case BTSTACK_CRYPTO_CMAC_MESSAGE:
case BTSTACK_CRYPTO_CMAC_GENERATOR:
btstack_crypto_cmac = (btstack_crypto_aes128_cmac_t *) btstack_crypto;
btstack_crypto_wait_for_hci_result = 1;
btstack_crypto_cmac = (btstack_crypto_aes128_cmac_t *) btstack_crypto;
if (btstack_crypto_cmac_state == CMAC_IDLE){
btstack_crypto_cmac_start(btstack_crypto_cmac);
} else {
btstack_crypto_cmac_handle_aes_engine_ready(btstack_crypto_cmac);
}
#endif
break;
case BTSTACK_CRYPTO_CCM_DIGEST_BLOCK:
@ -837,6 +923,7 @@ static void btstack_crypto_handle_random_data(const uint8_t * data, uint16_t len
btstack_crypto_run();
}
#ifndef USE_BTSTACK_AES128
static void btstack_crypto_handle_encryption_result(const uint8_t * data){
btstack_crypto_aes128_t * btstack_crypto_aes128;
btstack_crypto_aes128_cmac_t * btstack_crypto_cmac;
@ -961,6 +1048,7 @@ static void btstack_crypto_handle_encryption_result(const uint8_t * data){
break;
}
}
#endif
static void btstack_crypto_event_handler(uint8_t packet_type, uint16_t cid, uint8_t *packet, uint16_t size){
UNUSED(cid); // ok: there is no channel
@ -984,11 +1072,13 @@ static void btstack_crypto_event_handler(uint8_t packet_type, uint16_t cid, uint
break;
case HCI_EVENT_COMMAND_COMPLETE:
#ifndef USE_BTSTACK_AES128
if (HCI_EVENT_IS_COMMAND_COMPLETE(packet, hci_le_encrypt)){
if (!btstack_crypto_wait_for_hci_result) return;
btstack_crypto_wait_for_hci_result = 0;
btstack_crypto_handle_encryption_result(&packet[6]);
}
#endif
if (HCI_EVENT_IS_COMMAND_COMPLETE(packet, hci_le_rand)){
if (!btstack_crypto_wait_for_hci_result) return;
btstack_crypto_wait_for_hci_result = 0;

3
src/btstack_crypto.h
View File

@ -46,6 +46,7 @@
#define BTSTACK_CTRYPTO_H
#include "btstack_defines.h"
#include "btstack_config.h"
#if defined __cplusplus
extern "C" {
@ -270,7 +271,7 @@ void btstack_crypto_ccm_encrypt_block(btstack_crypto_ccm_t * request, uint16_t l
*/
void btstack_crypto_ccm_decrypt_block(btstack_crypto_ccm_t * request, uint16_t len, const uint8_t * ciphertext, uint8_t * plaintext, void (* callback)(void * arg), void * callback_arg);
#ifdef HAVE_AES128
#if defined(ENABLE_SOFTWARE_AES128) || defined (HAVE_AES128)
/**
* Encrypt plaintext using AES128
* @note Prototype for custom AES128 implementation