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use min encrytion key size, truncate key before using or distribution

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This commit is contained in:
matthias.ringwald@gmail.com 2013-12-06 22:19:32 +00:00
parent fd4c6f057c
commit 29ebd0071f
1 changed files with 34 additions and 15 deletions
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49
example/libusb/ble_server.c
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@ -250,8 +250,10 @@ static key_t sm_persistent_irk;
// ..
static uint8_t sm_accepted_stk_generation_methods;
static uint8_t sm_max_encrypted_key_size;
static uint8_t sm_min_encrypted_key_size;
static uint8_t sm_max_encryption_key_size;
static uint8_t sm_min_encryption_key_size;
static uint8_t sm_encryption_key_size;
static uint8_t sm_s_auth_req = 0;
static uint8_t sm_s_io_capabilities = IO_CAPABILITY_UNKNOWN;
static uint8_t sm_s_request_security = 0;
@ -368,6 +370,22 @@ static int sm_is_null_random(uint8_t random[8]){
return 1;
}
static void sm_reset_tk(){
int i;
for (i=0;i<16;i++){
sm_tk[i] = 0;
}
}
// "For example, if a 128-bit encryption key is 0x123456789ABCDEF0123456789ABCDEF0
// and it is reduced to 7 octets (56 bits), then the resulting key is 0x0000000000000000003456789ABCDEF0.""
static void sm_truncate_key(key_t key, int max_encryption_size){
int i;
for (i = max_encryption_size ; i < 16 ; i++){
key[15-i] = 0;
}
}
static void print_key(const char * name, key_t key){
printf("%-6s ", name);
hexdump(key, 16);
@ -506,13 +524,6 @@ static void sm_notify_client(uint8_t type, uint8_t addr_type, bd_addr_t address,
printf("sm_notify_client: event 0x%02x, addres_type %u, address (), num '%06u'", event.type, event.addr_type, event.passkey);
}
void sm_reset_tk(){
int i;
for (i=0;i<16;i++){
sm_tk[i] = 0;
}
}
// decide on stk generation based on
// - pairing request
// - io capabilities
@ -596,7 +607,7 @@ static void sm_run(void){
buffer[1] = sm_s_io_capabilities;
buffer[2] = sm_stk_generation_method == OOB ? 1 : 0;
buffer[3] = sm_s_auth_req;
buffer[4] = sm_max_encrypted_key_size;
buffer[4] = sm_max_encryption_key_size;
memcpy(sm_s_pres, buffer, 7);
@ -804,12 +815,18 @@ static void sm_packet_handler(uint8_t packet_type, uint16_t handle, uint8_t *pac
sm_m_max_encryption_key_size = packet[4];
// assert max encryption size above our minimum
if (sm_m_max_encryption_key_size < sm_min_encrypted_key_size){
if (sm_m_max_encryption_key_size < sm_min_encryption_key_size){
sm_pairing_failed_reason = SM_REASON_ENCRYPTION_KEY_SIZE;
sm_state_responding = SM_STATE_SEND_PAIRING_FAILED;
break;
}
// min{}
sm_encryption_key_size = sm_max_encryption_key_size;
if (sm_m_max_encryption_key_size < sm_max_encryption_key_size){
sm_encryption_key_size = sm_m_max_encryption_key_size;
}
// setup key distribution
sm_m_key_distribution = packet[5];
sm_setup_key_distribution(packet[6]);
@ -982,8 +999,8 @@ void sm_init(){
sm_accepted_stk_generation_methods = SM_STK_GENERATION_METHOD_JUST_WORKS
| SM_STK_GENERATION_METHOD_OOB
| SM_STK_GENERATION_METHOD_PASSKEY;
sm_max_encrypted_key_size = 16;
sm_min_encrypted_key_size = 7;
sm_max_encryption_key_size = 16;
sm_min_encryption_key_size = 7;
}
// END OF SM
@ -1153,6 +1170,7 @@ static void packet_handler (void * connection, uint8_t packet_type, uint16_t cha
break;
case SM_STATE_PH2_W4_STK:
swap128(&packet[6], sm_s_ltk);
sm_truncate_key(sm_s_ltk, sm_encryption_key_size);
print_key("stk", sm_s_ltk);
sm_state_responding = SM_STATE_PH2_SEND_STK;
break;
@ -1212,6 +1230,7 @@ static void packet_handler (void * connection, uint8_t packet_type, uint16_t cha
break;
case SM_STATE_PH4_LTK_W4_ENC:
swap128(&packet[6], sm_s_ltk);
sm_truncate_key(sm_s_ltk, sm_encryption_key_size);
print_key("ltk", sm_s_ltk);
sm_state_responding = SM_STATE_PH4_SEND_LTK;
break;
@ -1483,11 +1502,11 @@ void sm_set_accepted_stk_generation_method(uint8_t accepted_stk_generation_metho
}
void sm_set_max_encrypted_key_size(uint8_t size) {
sm_max_encrypted_key_size = size;
sm_max_encryption_key_size = size;
}
void sm_set_min_encrypted_key_size(uint8_t size) {
sm_min_encrypted_key_size = size;
sm_min_encryption_key_size = size;
}
void sm_set_authentication_requirements(uint8_t auth_req){