A jamming device for inhibiting unauthorized contactless reading of a contactless readable object is disclosed. In one embodiment, the jamming device includes: an antenna for receiving an interrogation signal from a reader device; a touch sensitive interface; and a circuit electrically connected to the antenna and the touch sensitive interface, wherein the circuit is configured to: operate in a first mode to generate and emit a jamming signal, via the antenna, in response to receiving the interrogation signal while the touch sensitive interface fails to indicate a touch event; and operate in a second mode while the touch sensitive interface indicates a touch event, wherein the jamming signal is not emitted via the antenna in response to receiving the interrogation signal while operating in the second mode. A card carrying object, system and method is also disclosed.

A method is provided for detecting an attack by electromagnetic waves on an electronic chip or system-in-package type device including an attack detection element comprising a GMI-effect electrically-conductive material. The method includes demagnetising the GMI-effect material such that the value of its remanent magnetisation is equal to a predefined value lower than the value of its maximum remanent magnetisation. The method further includes determining a first value of the impedance of the attack detection element, and then after a time period during which the device might have undergone an attack, measuring a second value of the impedance of the attack detection element by circulating in the GMI-effect electrically-conductive material an alternating current with the same frequency as when determining the first impedance value. The method also includes comparing the first and second values of the impedance of the attack detection element.