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implement stk generation method decision

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matthias.ringwald@gmail.com 2013-11-28 20:19:21 +00:00
parent 98dc099930
commit 1bebac1147
1 changed files with 67 additions and 15 deletions
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82
example/libusb/ble_server.c
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@ -163,6 +163,24 @@ typedef enum {
} security_manager_state_t;
typedef enum {
JUST_WORKS,
PK_INIT_INPUT, // Initiator displays PK, responder inputs PK
PK_RESP_INPUT, // Responder displays PK, initiator inputs PK
OK_BOTH_INPUT, // Only input on both, both input PK
OOB // OOB available on both sides
} stk_generation_method_t;
// horizontal: initiator capabilities
// vertial: responder capabilities
static const stk_generation_method_t stk_generation_method[5][5] = {
{ JUST_WORKS, JUST_WORKS, PK_INIT_INPUT, JUST_WORKS, PK_INIT_INPUT },
{ JUST_WORKS, JUST_WORKS, PK_INIT_INPUT, JUST_WORKS, PK_INIT_INPUT },
{ PK_RESP_INPUT, PK_RESP_INPUT, OK_BOTH_INPUT, JUST_WORKS, PK_RESP_INPUT },
{ JUST_WORKS, JUST_WORKS, JUST_WORKS, JUST_WORKS, JUST_WORKS },
{ PK_RESP_INPUT, PK_RESP_INPUT, PK_INIT_INPUT, JUST_WORKS, PK_RESP_INPUT },
};
static att_connection_t att_connection;
static uint16_t att_addr_type;
static bd_addr_t att_address;
@ -187,6 +205,7 @@ static key_t sm_aes128_plaintext;
//
static uint16_t sm_response_handle = 0;
static stk_generation_method_t sm_stk_generation_method;
// defines which keys will be send after connection is encrypted
static int sm_key_distribution_set = 0;
@ -209,9 +228,13 @@ static key_t sm_tk;
static key_t sm_m_random;
static key_t sm_m_confirm;
static uint8_t sm_m_have_oob_data;
static uint8_t sm_m_auth_req;
static uint8_t sm_m_io_capabilities = 0;
static uint8_t sm_preq[7];
static uint8_t sm_pres[7];
static uint8_t sm_s_auth_req = 0;
static uint8_t sm_s_io_capabilities = 0;
static key_t sm_s_random;
static key_t sm_s_confirm;
static key_t sm_stk;
@ -375,6 +398,40 @@ static void sm_s1_r_prime(key_t r1, key_t r2, key_t r_prime){
memcpy(&r_prime[0], &r1[8], 8);
}
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
// - OOB data availability
static void sm_tk_setup(){
// If both devices have out of band authentication data, then the Authentication
// Requirements Flags shall be ignored when selecting the pairing method and the
// Out of Band pairing method shall be used.
if (sm_m_have_oob_data && (*sm_get_oob_data)(att_addr_type, att_address, sm_tk)){
sm_stk_generation_method = OOB;
return;
}
// If both devices have not set the MITM option in the Authentication Requirements
// Flags, then the IO capabilities shall be ignored and the Just Works association
// model shall be used.
if ((sm_s_auth_req & sm_m_auth_req & 0x04) == 0){
sm_stk_generation_method = JUST_WORKS;
sm_reset_tk();
}
// Otherwise the IO capabilities of the devices shall be used to determine the
// pairing method as defined in Table 2.4.
sm_stk_generation_method = stk_generation_method[sm_m_io_capabilities][sm_s_io_capabilities];
}
static void sm_run(void){
// assert that we can send either one
@ -393,29 +450,29 @@ static void sm_run(void){
}
case SM_STATE_SEND_PAIRING_RESPONSE: {
// TODO use provided IO capabilites
// TOOD use local MITM flag
// TODO provide callback to request OOB data
// TODO use locally defined max encryption key size
uint8_t buffer[7];
memcpy(buffer, sm_preq, 7);
buffer[0] = SM_CODE_PAIRING_RESPONSE;
// buffer[1] = 0x00; // io capability: DisplayOnly
// buffer[1] = 0x02; // io capability: KeyboardOnly
// buffer[1] = 0x03; // io capability: NoInputNoOutput
buffer[1] = 0x04; // io capability: KeyboardDisplay
buffer[1] = sm_s_io_capabilities;
if (sm_get_oob_data){
buffer[2] = sm_get_oob_data(att_addr_type, att_address, NULL);
} else {
buffer[2] = 0x00; // no oob data available
}
buffer[3] = buffer[3] & 3; // remove MITM flag
buffer[3] = sm_s_auth_req;
buffer[4] = 0x10; // maxium encryption key size
// for validate
memcpy(sm_pres, buffer, 7);
l2cap_send_connectionless(sm_response_handle, L2CAP_CID_SECURITY_MANAGER_PROTOCOL, (uint8_t*) buffer, sizeof(buffer));
// decide on Passkey Entry pairing algorithm
sm_tk_setup();
sm_state_responding = SM_STATE_W4_PAIRING_CONFIRM;
return;
}
@ -549,7 +606,9 @@ static void sm_packet_handler(uint8_t packet_type, uint16_t handle, uint8_t *pac
case SM_CODE_PAIRING_REQUEST:
// store key distribtion request
sm_m_io_capabilities = packet[1];
sm_m_have_oob_data = packet[2];
sm_m_auth_req = packet[3];
sm_key_distribution_set = packet[6];
// for validate
@ -608,13 +667,6 @@ static void sm_packet_handler(uint8_t packet_type, uint16_t handle, uint8_t *pac
sm_run();
}
void sm_reset_tk(){
int i;
for (i=0;i<16;i++){
sm_tk[i] = 0;
}
}
static void sm_distribute_keys(){
// TODO: handle initiator case here