Method for protecting a logic or mathematical operator installed in an electronic module with a microprocessor as well as the associated embedded electronic module and the system

• US 9,323,955 B2
• Filed: 12/20/2001
• Issued: 04/26/2016
• Est. Priority Date: 12/21/2000
• Status: Active Grant

• Current Assignee: Thales DIS France SAS (Thales SA)
• Original Assignee: Gemalto SA (Thales SA)
• Inventors: Giraud, Nicolas, Hameau, Patrice, Brolh, Abraham
• Primary Examiner(s): Armouche, Hadi
• Assistant Examiner(s): Cribbs, Malcolm
• Application Number:
  US10/471,323
• Publication Number:
  US 20080016583A1
• Time in Patent Office: 5,241 Days
• Field of Search: 726 34- 36, 380 28- 30, 380/42, 380/207, 380/209, 380/210, 380/259, 380/264, 380/265, 380/268, 380/287, 708/200, 708/212
• US Class Current: 1/1
• CPC Class Codes: G06F 21/755 with measures against power attack

Abstract

The method for protecting a logic or mathematical operator of the NOR operator type, able to be used for executing a program in a microprocessor electronic module wherein the execution of the NOR operator is replaced by the execution (CAL-XORSEC(1) of a sequence Si operations having for final result a result identical to that of the XOR function.

The sequence of operations Si composed of elementary operations with AND, OR and NOT is selected at each XOR operator from a set of eight equivalent sequences (S1 to S8) after determination CAL-NDO) of an order number ND0=1 according to the parameters of the program and/or a random parameter R supplied by a pseudo-random number generator (14).

Claims

1. A method for protecting a logic or mathematical operator or a similar functional circuit able to be used for executing a program in an electronic module with a processor, wherein during the execution of the program, the execution of said operator is replaced by the execution of a sequence of replacement operations whose final result is identical to that of the function of said operator.

2. The method according to claim 1, wherein said sequence of replacement operations is selected on each call for said operator from a set of equivalent sequences.

3. The method according to claim 2, wherein each sequence has associated an order number therewith and wherein the sequence of replacement operations is selected by selecting a particular order number corresponding to one sequence and wherein the selected order number is determined according to certain parameters of the program being executed and/or a random parameter obtained from a pseudo-random number generator.

4. The method according to claim 2, wherein certain sequences include at least one non-operative instruction intended for introducing a delay time in the execution of the sequences in question, said non-operative instruction being selected from non-operative instructions in relation to the microprocessor or from instructions which are normally operative but rendered ineffective via their positions in the sequence of operations.

5. The method according to claim 2, wherein at least one sequence of replacement operations is made up of elementary logic operators.

6. The method according to claim 5, wherein at least one sequence of replacement operations is made up of AND, OR and NOT elementary logic operators.

7. An electronic module, comprising:

at least one microprocessor and one program stored in memory of the electronic module and comprising instructions to be executed by the microprocessor; and

wherein the program contains at least one logic or mathematical operator or similar functional circuit to be protected when executed by the microprocessor;

the microprocessor being programmed with instructions causing the microprocessor while executing the one program to replace the execution of said operator by the execution of a sequence of operations whose final result is identical to that of the function of said operator or functional circuit.

8. The electronic module according to claim 7, wherein the microprocessor is further programmed with instructions to select said sequence of operations on each call of said operator from a set of equivalent sequences.

9. The electronic module according to claim 8, wherein each said sequence has associated an order number therewith and wherein the microprocessor is further programmed to select a sequence by selecting a particular order number according to certain parameters of the program being executed and/or a random parameter generated by a pseudo-random numbers generator.

10. A system comprising an electronic module having at least one microprocessor and one program to be executed by the microprocessor, wherein the program contains at least one logic or mathematical operator or similar functional circuit to be protected when executed by the microprocessor, wherein the microprocessor is programmed with instructions to cause the microprocessor while executing the program to replace the execution of said at least one logic or operator or execution using said functional circuit by the execution of a sequence of operations whose final result is identical to that of the function of said operator or said functional circuit.

11. The system according to claim 10, wherein the microprocessor is further programmed with instructions to select said sequence of operations on each call of said operator or functional circuit from a set of equivalent sequences.

12. The system according to claim 11, wherein each said sequence has associated an order number therewith and wherein the microprocessor is further programmed to select a sequence by selecting a particular order number according to certain parameters of the program being executed and/or a random parameter generated by a pseudo-random numbers generator.