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sm: store non-truncated LTK in setup->sm_local_ltk for cross transport key derivation - see E6405

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This commit is contained in:
Matthias Ringwald 2016-06-27 17:11:08 +02:00
parent 893e933318
commit b18300a6ef
1 changed files with 10 additions and 1 deletions
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11
src/ble/sm.c
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@ -1406,7 +1406,12 @@ static void sm_sc_cmac_done(uint8_t * hash){
sm_conn->sm_engine_state = SM_SC_W2_CALCULATE_F5_LTK;
break;
case SM_SC_W4_CALCULATE_F5_LTK:
// truncate sm_ltk, but keep full LTK for cross-transport key derivation in sm_local_ltk
// Errata Service Release to the Bluetooth Specification: ESR09
// E6405 – Cross transport key derivation from a key of size less than 128 bits
// Note: When the BR/EDR link key is being derived from the LTK, the derivation is done before the LTK gets masked."
memcpy(setup->sm_ltk, hash, 16);
memcpy(setup->sm_local_ltk, 16);
sm_truncate_key(setup->sm_ltk, sm_conn->sm_actual_encryption_key_size);
sm_conn->sm_engine_state = SM_SC_W2_CALCULATE_F6_FOR_DHKEY_CHECK;
break;
@ -1701,8 +1706,12 @@ static void h6_engine(sm_connection_t * sm_conn, const sm_key_t w, const uint32_
sm_cmac_general_start(w, message_len, &sm_sc_cmac_get_byte, &sm_sc_cmac_done);
}
// For SC, setup->sm_local_ltk holds full LTK (sm_ltk is already truncated)
// Errata Service Release to the Bluetooth Specification: ESR09
// E6405 – Cross transport key derivation from a key of size less than 128 bits
// "Note: When the BR/EDR link key is being derived from the LTK, the derivation is done before the LTK gets masked."
static void h6_calculate_ilk(sm_connection_t * sm_conn){
h6_engine(sm_conn, setup->sm_ltk, 0x746D7031); // "tmp1"
h6_engine(sm_conn, setup->sm_local_ltk, 0x746D7031); // "tmp1"
}
static void h6_calculate_br_edr_link_key(sm_connection_t * sm_conn){