Patent ID: 7205794

Claim:
A logical circuit comprising at least one logical function and at least one connector connected to said logical function, wherein: said at least one connector has two wires for each logical connection, such that each wire has two logical states being a low logical state and a high logical state, thereby to define four logical signals of said conductor, characterised in that: the circuit further comprises at least one attack sensor, said attack sensor being arranged so as to produce a normal signal at all times except when an attack is detected, when an attack signal is produced; a first one of said low logical signals is an alarm signal, a second one is a low logical signal, a third one is a high logical signal, and a fourth is a clear signal; on the or one of said connectors, each of said wires is connected to the input of a separate logical gate, the other input of each of said logical gates is connected to the attack sensor, the output of said logical gates being the continuation of said connector; and said logical gates being constructed so as to propagate the logical states of said wires when the input signal from the attack sensor is a normal signal and to propagate an alarm signal when the input signal from the attack sensor is an attack signal, regardless of the input from said wires.