Patent Application
20080012690
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein the sole FIGURE illustrates a schematic representation of an RFID system, according to an embodiment of the present invention.
The FIGURE schematically shows an inventive RFID system 1, having at least one transponder 2 and a base station 3. A memory 4 is associated with the base station.
The transponder 2 has at least one first memory area 20 and one second memory area 22. The first memory area 20 is a private memory area that is accessible in clear text only by a read access internal to the transponder by a logic unit 24. The first memory area 20 is not externally readable. A first piece of information is stored in the first memory area 20. In the embodiment shown, the first piece of information is a symmetric password SPW. The transponder 2 has, for example, data areas that are not shown, wherein security-relevant access such as read and/or write access or locking access to the data areas is only possible by the transmission of the symmetric password SPW. The symmetric password is, for example, a “kill password” or an “access password” in conformity with the proposed standard ISO/IEC_CD 18000-6C mentioned above.
The second memory area 22 is accessible through an air interface for read access in clear text. In one embodiment, read access is accessible only under conditions, for example the successful completion of an arbitration process. Stored in the second memory area 22 is a second piece of information that is an asymmetric piece of information ASIG that is generated from the first piece of information using an asymmetric encryption method.
In the embodiment shown, encryption is performed using the elliptic-curve cryptosystem method (ECC method). In this process, base stations and transponders agree publicly on a valid elliptic curve and a point P on this curve.
The base station 3 secretly obtains a random number bs, which is stored in a memory 4, for example. In an analogous manner, the transponder 2 secretly obtains a random number ts that is known only to the transponder. In the embodiment shown, ts is stored in the memory area 20. In another embodiment, ts is generated anew for each transmission. A public key bp=bs·P can be calculated in the base station 3. This key is made available to the transponder 2. In an analogous manner, the transponder 2 determines a public key tp=ts·P, which in the embodiment shown is stored in the memory area 22 that is accessible for read access. In the elliptic-curve cryptosystem, S=bs·tp=ts·bp. Thus a key S is provided that can easily be calculated by both the transponder 2 and the base station 3 using the public keys tp and bp.
The base station 3 reads the second piece of information, i.e. the asymmetric information ASIG, from the second memory area 22 of the transponder 2. Using the private key bs, the key S and thus the symmetric password SPW can be extracted from the asymmetric information ASIG by the base station 3.
To request read and/or write access to the transponder 2, the base station 3 transmits the extracted symmetric password SPW to the transponder 2. In the embodiment shown, the transmission takes place using a known protocol, wherein the symmetric password SPW is encrypted by a random number RN, which in one embodiment has previously been transmitted from the transponder to the base station.
Although, in the example embodiment, the inventive method requires the transponder to have an additional memory area for storing the second piece of information, i.e. the asymmetric information, the method does permit significantly simpler management of passwords than prior art methods.
In the embodiment shown, the piece of information tp for decrypting the symmetric password for the base station 3 is located in the accessible memory area 22 of the transponder. In other embodiments, this information is available from other sources, for example through the Internet.
The private key bs can likewise be made available to the base station 3 through the Internet or another information source.
In one embodiment, a RFID system that includes a number of base stations 3 and transponders 2 is used for a ski pass system. Here, a transponder 2 is attached to a ski pass. Stored in a first data area of the transponder 2 is, for example, information on the term of validity and/or the area of validity of the ski pass. This information is accessible for read access to a number of base stations, for example lift stations. In the general case, the information can also be made available to any other desired base stations that are not part of the ski pass system, without concern as to security and/or data privacy. Wireless transmission permits especially convenient handling of the ski pass. However, write access to the memory area is denied to the simple base stations associated with the lift stations or to base stations that are not part of the ski pass system. For example, the validity of the ski pass can be changed at special ticket sales locations by the purchase of additional days and/or areas of validity. Base stations associated with the ticket sales locations thus require write access to the transponder. However, due to the large number of lift tickets and the large number of transponders associated therewith, a considerable effort is required if all possible symmetric passwords of the transponders are to be provided to all ticket sales locations. A considerable security gap is created if all transponders have an identical symmetric password, as successfully breaking into one transponder would then make the entire system accessible to the attacker.
Thus, according to the invention, a unique symmetric password SPW is stored on each transponder 2. According to the invention, an asymmetric information ASIG that is available to all base stations is generated from the symmetric password SPW. An authorized base station 3, for example at the ticket sales location, possesses a corresponding key by means of which it extracts the unique symmetric password SPW of the transponder 2 from the asymmetric information ASIG. By means of this password, the base station 3 of the ticket sales location obtains write access to certain data areas of the transponder 2 so that the validity of the lift ticket can be changed.
It is obvious that additional information can be stored on the transponder 2 that is used for a ski pass, for example data concerning a medical condition of a lift ticket holder; this information can be rapidly read out by rescue personnel in the event of an accident, for example, and can be immediately made available for life-saving measures. However, for reasons of data privacy this private information of the ticket holder should never be made available to base stations that are not associated with the rescue personnel. This information can be protected on the transponder by an additional symmetric password, wherein the rescue personnel can rapidly extract the symmetric password in case of need using the key provided to them.
The ski pass system described represents only one possible example application that demonstrates the great flexibility of the system, which is to say the easy extensibility of the system with additional transponders and/or base stations. Other scenarios in which the inventive transponders 2 are associated with goods and/or persons are also possible.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102006032130 | Jul 2006 | DE | national |
This nonprovisional application claims priority to German Patent Application No. DE 102006032130, which was filed in Germany on Jul. 5, 2006, and to U.S. Provisional Application No. 60/819,408, which was filed on Jul. 10, 2006, and which are both herein incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60819408 | Jul 2006 | US |
