Transponder System for Transmitting Key-Encrypted Information and Associated Keys

• US 20080199011A1
• Filed: 06/14/2006
• Published: 08/21/2008
• Est. Priority Date: 06/14/2005
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Skoric, Boris, Tombeur, Antoon Marie Henrie, Schrijen, Geert Jan, Maubach, Stefan, Tuyls, Pim Theo
• Granted Patent: US 9,830,481 B2
• Time in Patent Office: Days
• US Class Current: 380/268
• 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: G06K 19/14 the marking being sensed by radiation
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer

Abstract

A transponder (1) comprises at least one memory (MEM1, MEM2) for storing encrypted information (E_k(EPC, PI)) that has been encrypted by use of a key (k) and for storing the key (k) associated with the encrypted information (E_k(EPC, PI)). The transponder (1) is adapted to send the key (k) slower response than the encrypted information (E_k(EPC, PI)) in response to queries of a reading device (2), which is preferably done by delaying the transmission of the key (k) or by limiting the response rate at which the key (k) is transmitted. In particular the invention is related to RFID systems.

Claims

1. Transponder comprising at least one memory for storing encrypted information that has been encrypted by use of a key and for storing the key associated with the encrypted information, wherein the transponder is adapted to send, in response to queries of a reading device, the key slower than the encrypted information.

2. Transponder as claimed in claim 1, comprising key delay means being operative to pass the key in a time-delayed manner to transmitting means.

3. Transponder as claimed in claim 1, comprising response rate limiting means being operative to limit the response rate at which the key is passed to transmitting means.

4. Transponder as claimed in claim 1, wherein the encrypted information is stored in a fast-responding memory and the key is stored in a slow-responding memory.

5. Transponder as claimed in claim 1, comprising a random number generator for generating random numbers and encrypting means for computing randomized encrypted information, preferably semantically secure encrypted information, from the encrypted information or unencrypted information and from a random number.

6. Transponder as claimed in claim 1, wherein unencrypted information is stored in a blockable, and optionally also deblockable, memory.

7. Transponder as claimed in claim 1, comprising comparing means being adapted to compare a message received from the reading device with the key, and if the message corresponds to the key, to initiate the encrypted information to be read out from the memory.

8. Transponder as claimed in claim 1, comprising a random number generator for generating random number, challenge generating means for generating and sending to the reading device a challenge that includes a random number generated by the random number generator, and message analyzing means being adapted to analyze whether a message received from the reading device is derived from the random number previously sent with the challenge and from the key, and if so, to initiate the encrypted information to be read out from the memory.

12. System comprising transponders as claimed claim 1 and at least one reading device.

9. Reading device being adapted to send queries to transponders requesting encrypted information and a key associated with the encrypted information, wherein the reading device comprises decryption means to decrypt the encrypted information by use of the key.

10. Reading device as claimed in claim 9, comprising a data base wherein pairs of encrypted information and associated keys or pairs of encrypted information and associated unencrypted information are stored, wherein the reading device is adapted, when receiving encrypted information from a transponder, to retrieve the associated key from the database and to decrypt the encrypted information by use of the key, or to retrieve the associated unencrypted information.

11. Reading device as claimed in claim 9, comprising a message generator being adapted to generate messages that either is derived from a key previously received from a transponder or a key database, or from a key and a challenge both previously having been received from a transponder.