Method for operating a transponder

• US 6,753,759 B2
• Filed: 02/09/2001
• Issued: 06/22/2004
• Est. Priority Date: 12/07/1999
• Status: Expired due to Fees

• Current Assignee: Datamars SA (Province of Québec)
• Original Assignee: Datamars SA (Province of Québec)
• Inventors: Stegmaier, Peter, Hassan-Zade, Parvis
• Primary Examiner(s): Horabik, Michael
• Assistant Examiner(s): SHIMIZU, MATSUICHIRO
• Application Number:
  US09/762,674
• Publication Number:
  US 20020135478A1
• Time in Patent Office: 1,229 Days
• Field of Search: 340/10.51, 340/10.5, 340/10.52
• US Class Current: 340/10.51
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G08B 13/2417 having a radio frequency identification chip

Abstract

A transponder includes a data memory and a mechanism for contactless interaction with a base station. The transponder is brought (1) into an active field of the base station. Before the transponder is deactivated (7) by the base station by the transfer of a command signal (5), the authorization of the base station for deactivation (7) is checked (4). Before the transfer of the command signal (5) an admission signal which contains first admission information is transmitted (3) from the base station to the transponder. The first admission information with second admission information stored in the data memory is processed by the transponder into authorization information. Based on the authorization information it is decided (4) whether the command signal is accepted (7) or rejected (8). Thus the transponder while keeping secret the data present in the transponder may be reliably deactivated (7) or reactivated.

Claims

1. A method for operating a transponder which comprises a data memory and means for the contactless interaction with a base station;

wherein the transponder is brought into an active field of the base station and by the base station is respectively deactivatable, reactivatable by transferring a command signal,

characterised in that

before the respective deactivation, reactivation of the transponder the authorisation of the base station for respective deactivation, reactivation is checked, in that

from the base station before the transfer of the command signal an admission signal which contains first admission information is transferred to the transponder,

the admission signal is received by the transponder and

the first admission information with second admission information stored in the data memory is processed by the transponder into authorisation information, and

on account of the thus obtained authorisation information, in the transponder it is decided whether the command signal is accepted or rejected.

2. A method according to claim 1, wherein the first admission information contains

on the one hand a random number and

on the other hand a coded number set up from the random number with the help of a key known only to the transponder and base station

so that in the transponder by comparison of the random number to the coded number the authorisation of the base station may be ascertained on account of the presence of an identical key.

3. A method according to claim 1, wherein the first admission information contains

on the one hand a random number which is useable for a synchronisation of coding generators of the base station and of the transponder, and on the other hand a password which is coded with the help of a key known to the transponder and base station and which is likewise known to the transponder and the base station,

so that in the transponder the authorisation of the base station may be ascertained on account of a presence of an identical password.

4. A method according to claim 3, wherein the password after an effected proof of the authorisation of the base station is changeable in the transponder by the base station.

5. A method according to claim 2, wherein the key after an effected proof of the authorisation of the base station is changeable in the transponder by the base station.

6. A method according to claim 1, wherein as first and second admission information at least one secret, not publically accessible key is used.

7. A method according to claim 1, wherein as first and second admission information asymmetrical keys and suitable computation rules are used.

8. A method according to claim 1, wherein before the transfer of the admission signal, the base station and the transponder exchange non-protected data.

9. A method according to claim 1, wherein the base station after the sending of a command signal which deactivates the transponder, emits a control signal which would be answered by the non-deactivated transponder, and the base station displays an answer thereto as a warning signal.

10. A method according to claim 9, wherein before the display of the warning signal by way of the base station the deactivation signal is repeated once again or several times and only after a failed repeat is the warning signal displayed.

11. A method according to claim 1, wherein the transponder after receiving and ascertaining the correct admission signal answers with a confirmation signal which is different from this, said confirmation signal being recognised and confirmed by the base station.

12. A method according to claim 1, wherein the transponder after an acceptance of the command signal is deactivated respectively reactivated.

13. A method according to claim 12, wherein the deactivation is effected permanently and independently of the active field of the base station.

14. A method according to claim 4, wherein:

the key after an effected proof of the authorisation of the base station is changeable in the transponder by the base station;

as first and second admission information at least one secret, not publically accessible key is used and asymmetrical keys and suitable computation rules are used;

before the transfer of the admission signal, the base station and the transponder exchange non-protected data;

the base station after the sending of a command signal which deactivates the transponder, emits a control signal which would be answered by the non-deactivated transponder, and the base station displays an answer thereto as a warning signal while before the display of the warning signal by way of the base station the deactivation signal is repeated once again or several times and only after a failed repeat is the warning signal displayed;

the transponder after receiving and ascertaining the correct admission signal answers with a confirmation signal which is different from this, said confirmation signal being recognised and confirmed by the base station;

the transponder, after an acceptance of the command signal is respectively deactivated, reactivated; and

the deactivation is effected permanently and independently of the active field of the base station.