Android BLE get raw values from onCharacteristicChanged

Question

Is there a way to get the characteristic.value in onCharacteristicChanged as a byteArray of size 64 in binary?

I successfully subscribe to a notify-characteristic of a BLE Service (in Android/Kotlin). I know, that the data sent by the Bluetooth device consists of 64 bits (a UInt32 followed by two UInt16's). However, when I look at the value in onCharacteristicChanged, I get a byteArray of size 8 with values like this: [-120, -106, -57, 0, -1, -1, 20, 0] It should be a byteArray of size 64 with 0's and 1's. How can I achieve that?

This is the code that gives me the byteArray of size 8:

override fun onCharacteristicChanged(gatt: BluetoothGatt, characteristic: BluetoothGattCharacteristic) {
        with(characteristic) {
                Log.d(TAG, "value: ${Arrays.toString(value)}") //[-120, -106, -57, 0, -1, -1, 20, 0]
                Log.d(TAG,"value.size: ${value.size}") //8
        }
}