Evaluating security of a clone preventive techinque using physical randomness and cryptography

Clone resistance of most of all anti-counterfeiting techniques depends upon secret identifiers or difficulty of reproduction. However, these kinds of techniques are no use if a counterfeiter has enough financial a power to work the secret out or toe overcome the difficulty. We have focused on, among others, random patterns which can be inevitably difficult to reproduce. Consequently, we have developed a document protection system which utilizes random patterns of magnetic micro-fibers in substrates of documents. We have also applied cryptography to the system. The system verifies and authenticates a stochastic feature using pre-stored template data and a digital signature. The stochastic feature and the digital signature respectively prevent 'dead copying' and counterfeiting/alteration of the recorded data such as a value of the card. Therefore security of the system depends upon difficulty both in reproduction of the stochastic feature and in analysis of the digital signature. We have evalut3ed the security of the system for several kinds of criminal attacks. Some criminals may try to counterfeit a stochastic feature by modeling on a genuine document. In our paper we discuss security evaluation of our document protection system against such kinds of criminal methods and also discus a countermeasure and its difficulty.