| Abstract | RFID is a new technology developed to bring convenience in many areas. In a short period of time, RFID becomes one of popular topic and the use of RFID is growing rapidly.
This pervasive use of RFID causes many kinds of security concern such as tag cloning, data forgery, privacy violence, etc.
Many studies have been conducted to achieve a safety RFID system. Hopper and Blum proposed an authentication protocol called HB protocol based on the hardness of Learning Parity with Noise (LPN) problem. Later, Jonathan Katz et al and Julien Bringer et al modified the protocol to HB+ and HB++ to assure higher security against many kinds of attack. In this protocol, the tag is required to make some easy computation such as multiplication and addition. This means that this kind of authentication protocol cannot be applied only on passive tags which have no ability in computation. In practice, passive tags are used in many areas but currently we have not found any study in passive RFID tags yet.
Pairing cryptography is a new cryptosystem which requires shorter key length compared to RSA cryptography while the security level is almost the same.
ID-Based Encryption (IBE) is a cryptosystem in which public key is the user's unique information. In IBE, certification process of public key is unnecessary. Since the certificate of the public key is not needed, this cryptographic scheme is suitable for the low resource devices such as RFID tags. Florian Hess proposed a ID-Based signature scheme based on pairing. Dan Boneh et al proposed another algorithm of short signature based on pairing.
Since passive RFID tags have no ability of computation and small memory, dealing with the security problem in passive RFID tags is a difficult work. It is very hard to implement any encryption of data or digital signature with a cryptosystem where the key size is long.
In our work, we try to implement security solution of passive RFID tags. Our goal is to succeed in preventing data forgery in passive tags by implementing digital signature based on IBE and pairing. We also mean to evaluate the effectiveness of our proposed secure RFID in the real system.
We make use tag's unique ID (UID) as ID in ID-Based cryptosystem and we adopted the digital signature scheme based on Pairing by Dan Boneh. We also tried to implement another scheme by Florian Hess and compared both algorithms to find the most effective method for using in RFID.
Actually, we implemented the signature by applying 170-bit key. As a result, Hess's scheme produced a 1024-bit signature while Boneh's scheme produced a 170-bit signature. From the signature length viewpoint, we found that short signature scheme by Dan Boneh is more suitable with RFID than that of Florian Hess. However, we also found that the computing time needed in Boneh's scheme is about 10 times more than Hess's scheme.
To evaluate our prototype, we executed some experiments on our implemented system. We confirmed some effectiveness of ID-Based Signature and pairing in protecting data against forgery. Our system could successfully detect the maliciousness of falsification of data stored in the tags. Furthermore, from our work we could find some clue to the security solution in passive RFID tags as well as other kinds of RFID tags. We also noticed that in practice, the trade-off between signature length, computing time and security level is very important. |