Granted Patent B2

US 8,677,153 · App. 12/919,541 · Granted Mar 18, 2014

Abstract

Claims (25)

1. A method for protecting a cryptographic module, the method comprising:

estimating a functionality of a circuit that is adapted to malfunction when a physical parameter has a first value different from a nominal parameter value at which the cryptographic module functions correctly, the cryptographic module malfunctioning when said physical parameter has a second value different from said nominal parameter value and a difference between said first value and said nominal parameter value being smaller than a difference between said second value and said nominal parameter value, wherein said circuit is provided with a supply voltage of a first level and a clock signal that has a frequency that exceeds a first frequency threshold, wherein the cryptographic module is adapted to malfunction when being provided with a supply voltage of the first level and a clock signal that has a frequency that exceeds a second frequency threshold, wherein the second frequency threshold is higher than the first frequency threshold, wherein the first frequency threshold is higher than a nominal operational frequency of the cryptographic module when provided with a supply voltage of the first level; and

applying a cryptographic module protective measure if estimating that the circuit malfunctions.

2. The method according to claim 1 , wherein the applying comprises erasing an encryption key that is utilized by the cryptographic module if estimating that the circuit malfunctions.

3. The method according to claim 1 , wherein the applying comprises generating an alert.

4. The method according to claim 1 , wherein the estimating comprises evaluating a progress of a signal through at least a portion of the circuit.

5. The method according to claim 1 , wherein the clock signal provided to the circuit has a frequency that is lower than a frequency of a clock signal provided to at least one other component of an integrated circuit that comprises the cryptographic module.

6. The method according to claim 1 , comprising applying a cryptographic module protective measure if either one of the following conditions is fulfilled: (i) a level of a supply voltage is outside an allowed supply voltage level range; and (ii) a monitored temperature is outside an allowed temperature range.

7. The method according to claim 1 , comprising providing a circuit that resembles a critical path of the cryptographic module but malfunctions at lower frequencies than the critical path of the cryptographic module.

8. The method according to claim 7 comprising measuring a delay of the circuit in relation to a cycle of a clock signal that is provided to the circuit.

9. A computer program product stored on a nontransitory computer readable storage medium, the computer program product including code portions for performing a method as claimed in claim 1 when run on a programmable apparatus.

10. A device having cryptographic module protection capabilities, the device comprises:

a circuit;

a cryptographic module; and

a monitor;

wherein the circuit malfunctions when a physical parameter has a first value different from a nominal parameter value at which the cryptographic module functions correctly, the cryptographic module malfunctions when said physical parameter has a second value different from said nominal parameter value, a difference between said first value and said nominal parameter value being smaller than a difference between said second value and said nominal parameter value, wherein the circuit malfunctions when being provided with a supply voltage of a first level and a clock signal that has a frequency that exceeds a first frequency threshold, wherein the cryptographic module is adapted to malfunction when being provided with a supply voltage of the first level and a clock signal that has a frequency that exceeds a second frequency threshold, wherein the second frequency threshold is higher than the first frequency threshold, wherein the first frequency threshold is higher than a nominal operational frequency of the cryptographic module when provided with a supply voltage of the first level;

wherein the monitor estimates a functionality of the circuit and participates in an appliance of a cryptographic module protective measure if estimating that the circuit malfunctions.

11. The device according to claim 10 , wherein the device erases an encryption key that is utilized by the cryptographic module if the monitor estimates that the circuit malfunctions.

12. The device according to claim 10 , wherein the device erases an encryption key that is utilized by the cryptographic module if the monitor estimates that the circuit malfunctions.

13. The device according to claim 10 , wherein device generates an alert if the monitor estimates that the circuit malfunctions.

14. The device according to claim 10 , wherein the monitor evaluates a progress of a signal through at least a portion of the circuit.

15. The device according to claim 10 , wherein the clock signal provided to the circuit has a frequency that is lower than a frequency of a clock signal provided to at least one other component of an integrated circuit that comprises the cryptographic module.

16. The device according to claim 10 , adapted to apply a cryptographic module protective measure if either one of the following conditions is fulfilled: a level of a supply voltage is outside an allowed supply voltage level range; and a monitored temperature is outside an allowed temperature range.

17. The device according to claim 10 , wherein the circuit resembles a critical path of the cryptographic module but malfunctions at lower frequencies than the critical path of the cryptographic module.

18. The device according to claim 10 , wherein the monitor measures a delay of the circuit in relation to a cycle of a clock signal that is provided to the circuit.

Assignments (31)