I am building an Android authenticator for FIDO2. I got stuck with read/write characteristics. I am working on Mac - Chrome 75. Chrome can detect my Android BLE authenticator. After detecting my BLE Authenticator, onCharacteristicReadRequest() is called from authenticator side. Inside the onCharacteristicReadRequest() I am using the code written below but there is no response from client after that.
I have tried U2F with version 0b01000000. It's working fine. When I moved FIDO2 version 0b100000, I am facing this issue. I am advertising fido service and device info service from authenticator. Both services has been added with Thread.sleep(1000) interval. I couldn't add both services sequentially. When I add both services sequentially, I am getting ArrayIndexOutofBoundException.
I don't know if both issues are interlinked. Please correct me if I am doing anything wrong.
{
...
}else if (characteristic.getUuid().equals(FidoUUIDConstants.FIDO_SERVICE_REVISION_BITFIELD)) {
status = BluetoothGatt.GATT_SUCCESS;
ByteBuffer bb = ByteBuffer.allocate(1);
bb.order(ByteOrder.BIG_ENDIAN);
bb.put((byte) (1 << 5));
bytes = bb.array();
}
mGattServer.sendResponse(device, requestId, status, 0, bytes);
Client should read/write characteristics after fidoServiceBitFieldversion is expected.
I agreed with @Bao's concern. According to CTAP specification, you should define descriptor corresponding to each characteristic with READ/WRITE permission. Note that the UUIDs for each descriptor are needed a valid UUID 128-bit format. All descriptors have both permissions READ and WRITE. For example:
UUID CONTROL_POINT_DESCRIPTOR_UUID = UUID.fromString("00002901-0000-1000-8000-00805f9b34fb");
BluetoothGattDescriptor controlPointDescriptor = new BluetoothGattDescriptor(
CONTROL_POINT_DESCRIPTOR_UUID,
BluetoothGattDescriptor.PERMISSION_READ | BluetoothGattDescriptor.PERMISSION_WRITE
);