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sm: extract g2_calculate

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This commit is contained in:
Matthias Ringwald 2016-05-28 20:09:19 +02:00
parent 0346c37cbe
commit f92edc8e3a
1 changed files with 46 additions and 34 deletions
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80
src/ble/sm.c
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@ -623,28 +623,11 @@ static void aes_cmac(sm_key_t aes_cmac, const sm_key_t key, const uint8_t * data
aes128_calc_cyphertext(key, sm_cmac_y, aes_cmac);
}
// g2(U, V, X, Y) = AES-CMACX(U || V || Y) mod 2^32
// - U is 256 bits
// - V is 256 bits
// - X is 128 bits
// - Y is 128 bits
static uint32_t g2(const sm_key256_t u, const sm_key256_t v, const sm_key_t x, const sm_key_t y){
uint8_t buffer[80];
memcpy(buffer, u, 32);
memcpy(buffer+32, v, 32);
memcpy(buffer+64, y, 16);
sm_key_t cmac;
log_info("g2 key");
log_info_hexdump(x, 16);
log_info("g2 message");
log_info_hexdump(buffer, sizeof(buffer));
aes_cmac(cmac, x, buffer, sizeof(buffer));
log_info("g2 result");
log_info_hexdump(x, 16);
return big_endian_read_32(cmac, 12);
}
#if 0
//
// Link Key Conversion Function h6
//
// h6(W, keyID) = AES-CMACW(keyID)
// - W is 128 bits
// - keyID is 32 bits
@ -1308,6 +1291,7 @@ static inline void sm_pdu_received_in_wrong_state(sm_connection_t * sm_conn){
#ifdef ENABLE_LE_SECURE_CONNECTIONS
static void sm_sc_prepare_dhkey_check(sm_connection_t * sm_conn);
static void g2_calculate(sm_connection_t * sm_conn);
static void sm_sc_state_after_receiving_random(sm_connection_t * sm_conn){
if (sm_conn->sm_role){
@ -1320,16 +1304,10 @@ static void sm_sc_state_after_receiving_random(sm_connection_t * sm_conn){
sm_sc_prepare_dhkey_check(sm_conn);
break;
case NK_BOTH_INPUT: {
// calc Va if numeric comparison
// TODO: use AES Engine to calculate g2
uint8_t value[32];
mbedtls_mpi_write_binary(&le_keypair.Q.X, value, sizeof(value));
uint32_t va = g2(value, setup->sm_peer_qx, setup->sm_local_nonce, setup->sm_peer_nonce) % 1000000;
big_endian_store_32(setup->sm_tk, 12, va);
case NK_BOTH_INPUT:
g2_calculate(sm_conn);
sm_trigger_user_response(sm_conn);
break;
}
case PK_INIT_INPUT:
case PK_RESP_INPUT:
case OK_BOTH_INPUT:
@ -1508,6 +1486,7 @@ static inline void f5_ltk(sm_connection_t * sm_conn, sm_key_t t){
log_info_hexdump(sm_cmac_sc_buffer, message_len);
sm_cmac_general_start(t, message_len, &sm_sc_cmac_get_byte, &sm_sc_cmac_done);
}
static void f5_calculate_ltk(sm_connection_t * sm_conn){
f5_ltk(sm_conn, setup->sm_t);
}
@ -1528,6 +1507,44 @@ static void f6_engine(sm_connection_t * sm_conn, const sm_key_t w, const sm_key_
sm_cmac_general_start(w, 65, &sm_sc_cmac_get_byte, &sm_sc_cmac_done);
}
// g2(U, V, X, Y) = AES-CMACX(U || V || Y) mod 2^32
// - U is 256 bits
// - V is 256 bits
// - X is 128 bits
// - Y is 128 bits
static uint32_t g2(const sm_key256_t u, const sm_key256_t v, const sm_key_t x, const sm_key_t y){
uint8_t buffer[80];
memcpy(buffer, u, 32);
memcpy(buffer+32, v, 32);
memcpy(buffer+64, y, 16);
sm_key_t cmac;
log_info("g2 key");
log_info_hexdump(x, 16);
log_info("g2 message");
log_info_hexdump(buffer, sizeof(buffer));
aes_cmac(cmac, x, buffer, sizeof(buffer));
log_info("g2 result");
log_info_hexdump(x, 16);
return big_endian_read_32(cmac, 12);
}
static void g2_calculate(sm_connection_t * sm_conn) {
// calc Va if numeric comparison
// TODO: use AES Engine to calculate g2
uint8_t value[32];
mbedtls_mpi_write_binary(&le_keypair.Q.X, value, sizeof(value));
uint32_t vab;
if (sm_conn->sm_role){
// responder
vab = g2(setup->sm_peer_qx, value, setup->sm_peer_nonce, setup->sm_local_nonce);;
} else {
// initiator
vab = g2(value, setup->sm_peer_qx, setup->sm_local_nonce, setup->sm_peer_nonce);
}
vab = vab % 1000000;
big_endian_store_32(setup->sm_tk, 12, vab);
}
static void sm_sc_calculate_local_confirm(sm_connection_t * sm_conn){
uint8_t z = 0;
if (setup->sm_stk_generation_method != JUST_WORKS && setup->sm_stk_generation_method != NK_BOTH_INPUT){
@ -2030,12 +2047,7 @@ static void sm_run(void){
// responder
connection->sm_engine_state = SM_SC_W4_DHKEY_CHECK_COMMAND;
if (setup->sm_stk_generation_method == NK_BOTH_INPUT){
// calc Vb if numeric comparison
// TODO: use AES Engine to calculate g2
uint8_t value[32];
mbedtls_mpi_write_binary(&le_keypair.Q.X, value, sizeof(value));
uint32_t vb = g2(setup->sm_peer_qx, value, setup->sm_peer_nonce, setup->sm_local_nonce) % 1000000;
big_endian_store_32(setup->sm_tk, 12, vb);
g2_calculate(connection);
sm_trigger_user_response(connection);
}
} else {