Patent ID: 7478293

Claim:
Electronic circuit comprising: a number of logic cells; a number of configurable cells each comprising at least a multiplexer and a flip-flop; a number of control conductors connected, for some of them at least, to the configurable cells and on which control signals selectively circulate, received and/or emitted during the operating of a control circuit such as an access control, the configurable cells selectively adopting, depending on the control signals, a standard operating mode in which they are operationally connected to at least some of the logic cells with which they co-operate to create a logic circuit, and a test mode in which these configurable cells are operationally connected in chains to create a shift register equipped with a data input and a data output; and a spy circuit connected to control conductors, running a logic combination of the signals passing through these control conductors, and delivering an output signal selectively adopting a state representative of no faults or a state representative of attempted intrusion, depending on whether the combination of signals passing through the control conductors corresponds, or not, to a combination of control signals visible in an operating state authorized by the electronic circuit, wherein, if the spy circuit runs a combination of signals circulating through a first set of control conductors each of which is assigned to the transmitting of the chain control signal configuring the configurable cells in shift register, the spy circuit delivers at least an output signal of a first type adopting a state representative of no faults when the signals circulating through the first set of control conductors are simultaneously in the same state.