Method for the management of an application program loaded in a microcircuit medium

• US 5,191,608 A
• Filed: 09/11/1991
• Issued: 03/02/1993
• Est. Priority Date: 09/12/1990
• Status: Expired due to Term

• Current Assignee: Gemplus International SA (Thales SA)
• Original Assignee: Gemplus International SA (Thales SA)
• Inventors: Geronimi, Francois
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US07/757,726
• Time in Patent Office: 538 Days
• Field of Search: 380/4, 380/23, 380/25
• US Class Current: 713/187
• CPC Class Codes: G06F 21/51 at application loading time, e.g. accepting, rejecting, starting or inhibiting executable software based on integrity or source reliability
• CPC Class Codes: G06F 21/77 in smart cards
• CPC Class Codes: G06F 2221/2129 Authenticate client device independently of the user
• 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 20/3552 Downloading or loading of personalisation data
• CPC Class Codes: G06Q 20/357 Cards having a plurality of specified features
• CPC Class Codes: G06Q 20/3672 initialising or reloading thereof
• CPC Class Codes: G07F 7/082 Features insuring the integrity of the data on or in the card
• CPC Class Codes: G07F 7/1008 Active credit-cards provided with means to personalise their use, e.g. with PIN-introduction/comparison system

Abstract

To provide protection for the use of chip cards, the microprocessor of such a card is made, during the use of the card, to compute a signature according to complex encrypting algorithm taking account, firstly, of a secret code proper to the card and, secondly, of the instructions proper to the program. The signature thus computed is compared with a signature that has been pre-recorded in the card under the same conditions at the time of its delivery by the card-issuing party. It is shown that several uses can be authorized without jeopardizing their security.

Claims

1. A method for the management of an application program in a microcircuit-based medium, comprising the following steps:

preparing a first encrypted signature as a function of a secret code of the microcircuit and predetermined instructions of the program;

loading said signature into a programmable memory of the microcircuit;

loading said program into a program memory of the microcircuit;

preparing a second encrypted signature in the microprocessor of the microcircuit during the execution of said application program;

comparing the first signature to the second signature; and

allowing said program to run if the first signature equals the second signature.

2. A method according to claim 1, wherein the program is stored in an erasable programmable memory.

3. A method according to claim 1, wherein a secret code is loaded into the circuit, this code being dedicated to the preparation of this signature.

4. A method according to claim 2, wherein said second signature is prepared and wherein said second signature is compared only when the application program is loaded into a working memory.

5. A method according to any one of the claims 1 to 4, wherein after said second signature is prepared said signature is compared several times during the execution of the program.

6. A method according to any one of claims 1 to 4, wherein said second signature is loaded into a memory region of the microcircuit which can only be read internally.

7. A method according to any one of claim 1 to 4, wherein said signatures are prepared also as a function of an identification code contained in the card.