A technique for tamper protection of incoming data signal to an electronic device is disclosed. An intentional interference signal is generated and modulated onto the incoming data signal as one composite input signal, to prevent unauthorized acquisition of valid data from the incoming data signal. The magnitude of the interference signal is adjusted to correspond to the magnitude of the incoming data signal, thereby preventing an attacker from properly differentiating the two different signals and/or decoding the valid data from the composite input signal. Once the composite input signal is safely received within the device, the interference signal can be filtered out in either analog mode or digital mode.