transponder, reader, communication system, method for transmitting a fixed identification number to a reader, method for receiving a fixed identification number from a transponder, computer readable medium and program element.

摘要

Transponder (180) having stored a fixed identification number, which expands said identification number with a random number, encrypts said expanded number with a key, and sends it to a reader (160) on its request. Reader (160), which on request receives an encrypted number from a transponder (180), decrypts a received encrypted number with a key, which was also used by the transponder (180), and extracts a fixed identification number associated with the transponder (180).