Patent ID: 7171565

Claim:
A method of preventing counterfeiting of a smart card, comprising: providing a smart card with a cryptographic structure for authorizing the smart card which cannot be accessed completely by a predetermined small number of readings, wherein said cryptographic structure can be built only by whoever emits the card or an agent thereof; providing a reader for reading said smart card and including a database holding information related to unauthorized smart cards, said reader being on-line, such that said reader is operatively connected to a network, only when said database of said reader is being updated by said network, wherein said reader includes a random number generator, which, when a card is read, chooses a pair (a, b) of distinct numbers with a<b between l and N, wherein said smart card carries thereon predetermined N channels as C 1 , C 2 , . . . , CN, where N is an integer, wherein each channel Ci, with i equal to 1, 2, . . . , N, carries a pair of numbers (hi, li), and wherein hi is the i th high number and li is the i th low number, wherein said reader obtains a content of only two of said channels, and periodically communicating, by said reader of said smart card, with a database where a predetermined characteristic of the card is checked.