Patent ID: 7500110

Claim:
A method of increasing security of circuits against unauthorized access, comprising: receiving an input power supply signal; producing an output power supply signal that varies over time using the input power supply signal in response to control signals; providing the output power supply signal that varies over time to a self-timed circuit; performing data-processing operations at the self-timed circuit using the output power supply signal that varies over time in response to the control signals, the data-processing operations being performed at different clock frequencies due to the output power supply signal that varies over time to decouple signal traces associated with the data-processing operations so that security of the self-timed circuit is increased; and generating random numbers to produce the control signals to vary the output power supply signal over time; converting the random numbers from digital random number signals to analog random number signals, the analog random number signals being used as the control signals to vary the output power supply signal over time; and wherein the self-timed circuit is part of a smart card and wherein the producing the output power supply signal is performed by means that are part of a read/write device for the smart card.