Cryptography method and smart cards microcircuit

• US 20030163699A1
• Filed: 03/20/2003
• Published: 08/28/2003
• Est. Priority Date: 05/31/2000
• Status: Active Grant

• Current Assignee: Orange S.A.
• Original Assignee: Orange S.A.
• Inventors: Girault, Marc, Pailles, Jean-Claude
• Granted Patent: US 7,802,098 B2
• Time in Patent Office: Days
• US Class Current: 713/172
• CPC Class Codes: G06Q 20/341 Active cards, i.e. cards including their own processing means, e.g. including an IC or chip
• CPC Class Codes: G06Q 20/367 involving electronic purses or money safes
• CPC Class Codes: G06Q 20/40975 using encryption therefor
• CPC Class Codes: G07F 7/084 Additional components relating to data transfer and storing, e.g. error detection, self-diagnosis
• CPC Class Codes: G07F 7/1008 Active credit-cards provided with means to personalise their use, e.g. with PIN-introduction/comparison system

Abstract

Method of cryptography in a smart card comprising a central processing unit, said method implementing precomputation operations, characterized in that said precomputation operations are performed by the smart card and in that the precomputation operations are carried out at a session during the waiting periods of the inputs/outputs of the central processing unit.

Claims

1. Method of cryptography comprising cryptographic computation steps implemented by a smart card comprising a central processing unit, said method furthermore implementing one or more precomputation steps, characterized in that said precomputation step or steps are performed by the smart card itself and in that said precomputation step or steps are performed at a session operated by the smart card and during input-output waiting periods of its central processing unit.

2. Method of cryptography according to claim 1, characterized in that said method implements an algorithm based on the computation of a discrete logarithm.

3. Method of cryptography according to one of the above claims, characterized in that the precomputations comprise computations of exponentiation.

4. Method of cryptography according to one of the above claims, characterized in that the precomputations are performed in steps by carrying out intermediate computations, and in that the results of these intermediate computations are stored in the smart card.

5. Microcircuit for smart card capable of communicating with the exterior through an input-output interface (I), comprising task-execution means (ET) including a computation task (PC) and means (GE) for the management of the execution of the tasks, characterized in that the management means (GE) comprise means (APC) for the activation of the computation task (PC) during the waiting times pertaining to the other task or tasks active on the microcircuit.

6. Microcircuit according to claim 5, characterized in that the task execution means (ET) comprise a microprocessor (UC), a program memory (M1) comprising the task execution management program and an applications program memory (M3) comprising the executable task or tasks in the form of one or more application programs.

7. Microcircuit according to claim 6, characterized in that the task execution means (ET) furthermore comprise a cryptographic computation circuit (CP).

8. Microcircuit according to one of the claims 5 to 7, characterized in that the task execution means (ET) are capable of carrying out computations of exponentiation

9. Microcircuit according to one of the claims 5 to 8, characterized in that the computation task activation means (APC) comprise a circuit (O) for the scheduling of the inputs-outputs of/on the card capable of activating the task execution means (ET) when said scheduling circuit (O) is awaiting an input or an output.

10. Microcircuit according to one of the claims 5 to 9, characterized in that it comprises means (M3) for the storage of the results of said computations.

11. Contactless microcircuit card characterized in that it comprises a microcircuit according to one of the claims 5 to 10.

12. Contact-type microcircuit card characterized in that it comprises a microcircuit according to one of the claims 5 to 10.

13. Microcircuit card working in contactless mode or in contact mode, characterized in that it comprises a microcircuit according to one of the claims 5 to 10.