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basic pairing with key distribution and reconnects mostly works

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matthias.ringwald@gmail.com 2013-11-09 22:14:32 +00:00
parent c9af4d3f19
commit 311a7e6675
1 changed files with 112 additions and 33 deletions
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145
example/libusb/ble_server.c
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@ -93,11 +93,17 @@ typedef enum {
#define SM_REASON_CONFIRM_VALUE_FAILED 0x04
#define SM_REASON_PAIRING_NOT_SUPPORTED 0x05
#define SM_REASON_ENCRYPTION_KEY_SIZE 0x06
#define SM_REASON_COMMAND_NOT_SUPPORTED 0x07
#define SM_REASON_UNSPECIFIED_REASON 0x08
#define SM_REASON_REPEATED_ATTEMPTS 0x09
// also, invalid parameters
// and reserved
typedef uint8_t key_t[16];
typedef enum {
SM_STATE_IDLE,
SM_STATE_C1_GET_RANDOM_A,
SM_STATE_C1_W4_RANDOM_A,
SM_STATE_C1_GET_RANDOM_B,
@ -107,6 +113,15 @@ typedef enum {
SM_STATE_C1_GET_ENC_B,
SM_STATE_C1_W4_ENC_B,
SM_STATE_C1_SEND,
SM_STATE_W4_LTK_REQUEST,
SM_STATE_W4_CONNECTION_ENCRYPTED,
SM_STATE_PH3_GET_RANDOM,
SM_STATE_PH3_W4_RANDOM,
SM_STATE_PH3_GET_DIV,
SM_STATE_PH3_W4_DIV,
} security_manager_state_t;
static att_connection_t att_connection;
@ -118,6 +133,13 @@ static uint8_t att_response_buffer[28];
static key_t sm_persistent_er;
static key_t sm_persistent_ir;
// derived from sm_persistent_ir
static key_t sm_persistent_dhk;
static key_t sm_persistent_irk;
// derived from sm_persistent_er
static uint16_t sm_response_handle = 0;
static uint16_t sm_response_size = 0;
static uint8_t sm_response_buffer[28];
@ -148,10 +170,13 @@ static key_t sm_m_confirm;
static uint8_t sm_preq[7];
static uint8_t sm_pres[7];
static key_t sm_stk;
static key_t sm_s_random;
static key_t sm_s_confirm;
static uint8_t sm_pairing_failed_reason = 0;
static uint16_t sm_s_div;
// key distribution, slave sends
static key_t sm_s_ltk;
@ -192,23 +217,6 @@ static void att_packet_handler(uint8_t packet_type, uint16_t handle, uint8_t *pa
// SECURITY MANAGER (SM) MATERIALIZES HERE
void sm_init(){
// set some (BTstack default) ER and IR
int i;
for (i=0;i<16;i++){
sm_persistent_er[i] = 0x30 + i;
sm_persistent_ir[i] = 0x90 + i;
}
}
void sm_set_er(key_t er){
memcpy(sm_persistent_er, er, 16);
}
void sm_set_ir(key_t ir){
memcpy(sm_persistent_ir, ir, 16);
}
static inline void swap128(uint8_t src[16], uint8_t dst[16]){
int i;
for (i = 0; i < 16; i++)
@ -482,6 +490,8 @@ static void sm_run(void){
switch (sm_state_responding){
case SM_STATE_C1_GET_RANDOM_A:
case SM_STATE_C1_GET_RANDOM_B:
case SM_STATE_PH3_GET_RANDOM:
case SM_STATE_PH3_GET_DIV:
hci_send_cmd(&hci_le_rand);
sm_state_responding++;
return;
@ -493,7 +503,7 @@ static void sm_run(void){
buffer[0] = SM_CODE_PAIRING_CONFIRM;
memcpy(&buffer[1], sm_s_confirm, 16);
l2cap_send_connectionless(sm_response_handle, L2CAP_CID_SECURITY_MANAGER_PROTOCOL, (uint8_t*) buffer, sizeof(buffer));
sm_state_responding = SM_STATE_IDLE;
sm_state_responding = SM_STATE_W4_LTK_REQUEST;
return;
}
default:
@ -670,6 +680,46 @@ void sm_reset_tk(){
}
}
static void sm_distribute_keys(){
// TODO: handle initiator case here
// distribute keys as requested by initiator
if (sm_key_distribution_set & SM_KEYDIST_ENC_KEY)
sm_send_encryption_information = 1;
sm_send_master_identification = 1;
if (sm_key_distribution_set & SM_KEYDIST_ID_KEY)
sm_send_identity_information = 1;
sm_send_identity_address_information = 1;
if (sm_key_distribution_set & SM_KEYDIST_SIGN)
sm_send_signing_identification = 1;
}
void sm_set_er(key_t er){
memcpy(sm_persistent_er, er, 16);
}
void sm_set_ir(key_t ir){
memcpy(sm_persistent_ir, ir, 16);
sm_dhk(sm_persistent_ir, sm_persistent_dhk);
sm_irk(sm_persistent_ir, sm_persistent_irk);
}
void sm_init(){
// set some (BTstack default) ER and IR
int i;
key_t er;
key_t ir;
for (i=0;i<16;i++){
er[i] = 0x30 + i;
ir[i] = 0x90 + i;
}
sm_set_er(er);
sm_set_ir(ir);
sm_state_responding = SM_STATE_IDLE;
}
// END OF SM
// enable LE, setup ADV data
@ -706,7 +756,8 @@ static void packet_handler (void * connection, uint8_t packet_type, uint16_t cha
// TODO support private addresses
sm_s_addr_type = 0;
BD_ADDR_COPY(sm_s_address, hci_local_bd_addr());
printf("Incoming connection, own address ");
print_bd_addr(sm_s_address);
// request security
sm_send_security_request = 1;
@ -715,9 +766,23 @@ static void packet_handler (void * connection, uint8_t packet_type, uint16_t cha
break;
case HCI_SUBEVENT_LE_LONG_TERM_KEY_REQUEST:
// sm_s1(sm_tk, sm_m_random, sm_m_random, sm_s_ltk);
// hci_send_cmd(&hci_le_long_term_key_request_reply, READ_BT_16(packet, 3), sm_s_ltk);
hci_send_cmd(&hci_le_long_term_key_negative_reply, READ_BT_16(packet, 3));
log_info("LTK Request, state %u", sm_state_responding);
if (sm_state_responding == SM_STATE_W4_LTK_REQUEST){
// calculate STK
log_info("calculating STK");
sm_s1(sm_tk, sm_s_random, sm_m_random, sm_stk);
hci_send_cmd(&hci_le_long_term_key_request_reply, READ_BT_16(packet, 3), sm_stk);
sm_state_responding = SM_STATE_W4_CONNECTION_ENCRYPTED;
break;
}
// re-establish previously used LTK using Rand and EDIV
log_info("recalculating LTK");
memcpy(sm_s_rand, &packet[5], 8);
sm_s_ediv = READ_BT_16(packet, 13);
sm_s_div = sm_div(sm_persistent_dhk, sm_s_rand, sm_s_ediv);
sm_ltk(sm_persistent_er, sm_s_div, sm_s_ltk);
hci_send_cmd(&hci_le_long_term_key_request_reply, READ_BT_16(packet, 3), sm_s_ltk);
sm_state_responding = SM_STATE_IDLE;
break;
default:
@ -725,17 +790,11 @@ static void packet_handler (void * connection, uint8_t packet_type, uint16_t cha
}
break;
case HCI_EVENT_ENCRYPTION_CHANGE:
// distribute keys as requested by initiator
// TODO: handle initiator case here
if (sm_key_distribution_set & SM_KEYDIST_ENC_KEY)
sm_send_encryption_information = 1;
sm_send_master_identification = 1;
if (sm_key_distribution_set & SM_KEYDIST_ID_KEY)
sm_send_identity_information = 1;
sm_send_identity_address_information = 1;
if (sm_key_distribution_set & SM_KEYDIST_SIGN)
sm_send_signing_identification = 1;
case HCI_EVENT_ENCRYPTION_CHANGE:
log_info("Connection encrypted");
if (sm_state_responding == SM_STATE_W4_CONNECTION_ENCRYPTED) {
sm_state_responding = SM_STATE_PH3_GET_RANDOM;
}
break;
case HCI_EVENT_DISCONNECTION_COMPLETE:
@ -774,9 +833,29 @@ static void packet_handler (void * connection, uint8_t packet_type, uint16_t cha
// calculate s_confirm
sm_c1(sm_tk, sm_s_random, sm_preq, sm_pres, sm_m_addr_type, sm_s_addr_type, sm_m_address, sm_s_address, sm_s_confirm);
// send s_confirm
sm_state_responding = SM_STATE_C1_SEND;
break;
case SM_STATE_PH3_W4_RANDOM:
memcpy(sm_s_rand, &packet[6], 8);
sm_state_responding = SM_STATE_PH3_GET_DIV;
break;
case SM_STATE_PH3_W4_DIV:
// use 16 bit from random value as div
sm_s_div = READ_NET_16(packet, 6);
// done
sm_state_responding = SM_STATE_IDLE;
// calculate EDIV and LTK
sm_s_ediv = sm_ediv(sm_persistent_dhk, sm_s_rand, sm_s_div);
sm_ltk(sm_persistent_er, sm_s_div, sm_s_ltk);
// distribute keys
sm_distribute_keys();
break;
default:
break;
}