Locking of an Integrated Circuit

• US 20080243973A1
• Filed: 09/27/2005
• Published: 10/02/2008
• Est. Priority Date: 09/28/2004
• Status: Active Grant

• Current Assignee: STMicroelectronics SA (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SA (STMicroelectronics NV)
• Inventors: Wuidart, Luc, Marinet, Fabrice
• Granted Patent: US 8,745,107 B2
• Time in Patent Office: Days
• US Class Current: 708/146
• CPC Class Codes: G06K 19/073 Special arrangements for circuits, e.g. for protecting identification code in memory protection against unauthorised use of computer memory G06F12/14
• CPC Class Codes: G06K 19/07363 by preventing analysis of the circuit, e.g. dynamic or static power analysis or current analysis
• CPC Class Codes: G06K 19/07372 by detecting tampering with the circuit
• CPC Class Codes: G06K 19/07716 the record carrier comprising means for customization, e.g. being arranged for personalization in batch
• CPC Class Codes: G06Q 20/3558 Preliminary personalisation for transfer to user
• CPC Class Codes: G07F 7/1008 Active credit-cards provided with means to personalise their use, e.g. with PIN-introduction/comparison system
• CPC Class Codes: H01L 27/0203 Particular design considerations for integrated circuits

Abstract

A method for protecting an integrated circuit. According to the method, the start-up of all, or part, of the circuit is determined in the presence of a key which is recorded in a non-volatile manner in the circuit, following the production thereof, and depends on at least one first parameter which is present in a non-volatile manner in the circuit after the production thereof.

Claims

1. A method for protecting an integrated circuit comprising conditioning the starting of all or part of the circuit to the presence of a key, generated outside of said circuit and recorded in non-volatile fashion subsequently to its manufacturing, said key depending on at least one first parameter present in non-volatile fashion in the circuit at the end of its manufacturing.

2. The method of claim 1, comprising:

applying a calculation function integrated to the circuit at least to said key; and

checking whether the result of the calculation complies with a predetermined value.

3. The method of claim 2, wherein the recording of said key in the integrated circuit is only allowed by said circuit if the application of said function to the key complies with said value.

4. The method of claim 2, wherein said function has as operands at least said key and said first parameter formed of an identification number of the circuit.

5. The method of claim 2, wherein said key is generated, outside of the circuit, based on said parameter and the function to comply with said value.

6. The method of claim 2, wherein the function takes into account a second parameter present in non-volatile fashion in the circuit at the end of its manufacturing.

7. The method of claim 6, wherein said second parameter depends on the position of the chip containing the integrated circuit in a wafer supporting several chips.

8. The method of claim 1, wherein said parameter differs from one integrated circuit chip to another or from one group of chips to another.

11. A method for manufacturing integrated circuit chips, comprising varying, within a same set of masks defining several circuits, a calculation function depending on a parameter for the implementation of the protection method of claim 8.

9. A method for personalizing an integrated circuit comprising a calculation function, at least one first parameter present in non-volatile fashion in the circuit at the end of its manufacturing and an element for calculating the function and for checking the result with respect to a predetermined value, comprising:

calculating, outside of the circuit and based on said parameter and on the function, a key such that the application of the function to the key provides a result complying with a predetermined property;

transferring the calculated key to the circuit;

applying, in the circuit, said calculation function to the calculated key; and

allowing the recording of the key in the integrated circuit in non-volatile fashion only if the result complies with said property.

10. (canceled)

12. An integrated circuit comprising an element for storing a key in non-volatile fashion and an element for storing or extracting at least one parameter from the circuit comprising means for conditioning the starting of all or part of the circuit to the presence of the key in the circuit, this key having been generated outside of the circuit depending on said parameter.

13. (canceled)