Integrated circuit for memorizing and processing information confidentially, including an anti-fraud device

Claim 1

An integrated circuit for memorizing and processing information confidentially, comprising: an electrically programmable non-volatile memory containing, among other things, enabling data; input/output means for coupling the circuit to a data transfer device; processing means interconnected between the input/output means and the non-volatile memory, said processing means being provided with an n-bit address counter, a read/write control logic and an access control circuit; said access control circuit including: a decoder circuit for decoding n-bit access codes introduced by way of the input/output means, said decoder circuit having a blocking input for inhibiting its operation; a comparator with two inputs connected respectively to an output of the decoder circuit and an output of the non-volatile memory to allow comparison of an n-bit access code stored in the memory and an n-bit code transmitted by the decoder circuit; said comparator having an output connected to the input of a flip-flop, the output of said flip-flop being connected to one input of a time-delay circuit for imparting a minimum predetermined delay between two attempts at introducing a confidential n-bit access code; said time-delay circuit having a first and a second input and one output: said first input connected to an output of the n-bit address counter which outputs a charging signal upon reception of n bits at the decoder circuit, said second input connected to the output of the flip-flop, said output of the time-delay circuit being connected to the blocking input of the decoder circuit; said time-delay circuit outputting to the decoder circuit a blocking signal of a predetermined minimum duration corresponding to a delay necessary to discharge the time-delay circuit.