Research On Key Technologies Of Mobile Commerce Security

Mobile commerce eliminates spatio-temporal limitations and extends the boundary of the INTERNET. It enables information exchange and commerce trade to take place at any time from any where. However, security issues have become the main bottleneck that restricts the growth of mobile commerce. Considering the great differences in transmission technologies and terminal's capability, it is unfeasible to copy the traditional electronic commerce's schemes directly to the mobile commerce occasions.The research focuses on key technologies in the security of mobile commerce, such as non-repudiation and privacy protection. The main achievements of the dissertation list as follows:(1) A device-based non-repudiation framework was proposed, which exceeded the ISO non-repudiation framework. Under the new framework, several non-repudiation mechanisms which fit the practical situations better are presented based on different trust relation between subjects (such as evidence subject, evidence user and arbiter) and objects (such as evidence generator, evidence verifier and arbiter device). In addtion, those mechanisms only using symmetric key cryptography suited resource-constrained devices particularly well.(2) A new hash chain, i.e. multi-path hash chain, was introduced. It avoids the linkage issues between neighbour nodes of a normal hash chain. Based on Asokan's server-supported signature and multi-path hash chain, an efficient anonymous signature protocol was proposed.(3) After comprehensive analysis of the iKP protocol, the dissertation pointed out its drawbacks. An improved secure electronic payment protocol was presented, which preserves the security properties of the iKP protocol with less communication payload in the transaction, reduced signature verifications, support of identification and evidence collection during goods delivery, perfect privacy protection for purchase, and assurance that the consumers have already possessed the goods before the bank clearing starts.(4) Two types of blind signature algorithms were proposed based on deterministic 0W-CT-CCA2 secure homomorphic encryption algorithms and deterministic 0W-CT-CCA2 secure commutative encryption algorithms (in which ciphertexts will leak no information and decision plaintext-ciphertext pair problems could be solved). Under the random oracle model, they were proved to be secure. When these signature algorithms are applied to mobile environment, encryption algorithms based on ellipse curve are preferable to reduce computation payload.(5) An exact definition of unlinkability for blind signature was presented together with a general proof framework. Under this framework, seveal typical blind signatures were analyzed, such as common blind signature, partially blind signature, randomized blind signature and restrictive blind signature. Thereafter, some suggestions on blind signature design were given.(6) Three types of adaptive k-out-of-n oblivious transfer protocols were proposed based on deterministic blind signature algorithms, deterministic 0W-CT-CCA2 secure commutative encryption algorithms (in which ciphertext will leak no information) and deterministic 0W-CT-CCA2 secure homomorphic encryption algorithms. Their security proofs were given under the random oracle model as well. Moreover, a DRM scheme base on an adaptive k-out-of-n oblivious transfer protocol was put forward to achieve privacy protection in DRM system. Computation cost could also be further reduced with oblivious transfer protocols based on ellipse curve, if they are applied to mobile environment.