Security: Cross-transport key derivation for Pairing initiated over LE (4fd7be86) · Commits · e / os / android_packages_modules_Bluetooth

system/gd/security/initial_informations.h

+12 −5

Original line number	Diff line number	Diff line
		@@ -37,11 +37,18 @@
		namespace bluetooth {
		namespace security {

		using DistributedKeys =
		std::tuple<std::optional<crypto_toolbox::Octet16> /* ltk /, std::optional<uint16_t> /ediv*/,
		std::optional<std::array<uint8_t, 8>> /* rand /, std::optional<Address> / Identity address */,
		AddrType, std::optional<crypto_toolbox::Octet16> /* IRK */,
		std::optional<crypto_toolbox::Octet16>> /* Signature Key */;
		struct DistributedKeys {
		/* LE Keys*/
		std::optional<crypto_toolbox::Octet16> ltk;
		std::optional<uint16_t> ediv;
		std::optional<std::array<uint8_t, 8>> rand;
		std::optional<hci::AddressWithType> identity_address;
		std::optional<crypto_toolbox::Octet16> irk;
		std::optional<crypto_toolbox::Octet16> signature_key;

		/* BR/EDR Keys */
		std::optional<crypto_toolbox::Octet16> link_key;
		};

		/* This class represents the result of pairing, as returned from Pairing Handler */
		struct PairingResult {

system/gd/security/pairing_handler_le.cc

+19 −5

Original line number	Diff line number	Diff line
		@@ -161,6 +161,14 @@ void PairingHandlerLe::PairingMain(InitialInformations i) {
		return;
		}

		// If it's secure connections pairing, do cross-transport key derivation
		DistributedKeys distributed_keys = std::get<DistributedKeys>(keyExchangeStatus);
		if ((pairing_response.GetAuthReq() & AuthReqMaskSc) && distributed_keys.ltk.has_value()) {
		bool use_h7 = (pairing_response.GetAuthReq() & AuthReqMaskCt2);
		Octet16 link_key = crypto_toolbox::ltk_to_link_key(*(distributed_keys.ltk), use_h7);
		distributed_keys.link_key = link_key;
		}

		// bool bonding = pairing_request.GetAuthReq() & pairing_response.GetAuthReq() & AuthReqMaskBondingFlag;

		i.OnPairingFinished(PairingResult{
		@@ -323,8 +331,7 @@ DistributedKeysOrFailure PairingHandlerLe::ReceiveKeys(const uint8_t& keys_i_rec
		std::optional<Octet16> ltk; /* Legacy only */
		std::optional<uint16_t> ediv; /* Legacy only */
		std::optional<std::array<uint8_t, 8>> rand; /* Legacy only */
		std::optional<Address> identity_address;
		AddrType identity_address_type;
		std::optional<hci::AddressWithType> identity_address;
		std::optional<Octet16> irk;
		std::optional<Octet16> signature_key;

		@@ -367,8 +374,10 @@ DistributedKeysOrFailure PairingHandlerLe::ReceiveKeys(const uint8_t& keys_i_rec
		return std::get<PairingFailure>(iapacket);
		}
		LOG_INFO("Received Identity Address Information");
		identity_address = std::get<IdentityAddressInformationView>(iapacket).GetBdAddr();
		identity_address_type = std::get<IdentityAddressInformationView>(iapacket).GetAddrType();
		auto iapacketview = std::get<IdentityAddressInformationView>(iapacket);
		identity_address = hci::AddressWithType(iapacketview.GetBdAddr(), iapacketview.GetAddrType() == AddrType::PUBLIC
		? hci::AddressType::PUBLIC_DEVICE_ADDRESS
		: hci::AddressType::RANDOM_DEVICE_ADDRESS);
		}

		if (keys_i_receive & KeyMaskSign) {
		@@ -382,7 +391,12 @@ DistributedKeysOrFailure PairingHandlerLe::ReceiveKeys(const uint8_t& keys_i_rec
		signature_key = std::get<SigningInformationView>(packet).GetSignatureKey();
		}

		return DistributedKeys{ltk, ediv, rand, identity_address, identity_address_type, irk, signature_key};
		return DistributedKeys{.ltk = ltk,
		.ediv = ediv,
		.rand = rand,
		.identity_address = identity_address,
		.irk = irk,
		.signature_key = signature_key};
		}

		void PairingHandlerLe::SendKeys(const InitialInformations& i, const uint8_t& keys_i_send, Octet16 ltk, uint16_t ediv,