Study Of Two-Party Computation With Publicly Verifiable Covert Security And Application Protocol Based On Oblivious Transfer

With the rapid development of a new generation of information technology such as 5G,and cloud computing,the world has entered the era of digital economy.Data are the core of the digital economy,and releasing the value of data thoroughly is an important cornerstone for the healthy development of the digital economy.However,the prevalence of "data silos",frequent big data leaks and increasingly strict data compliance laws and policies have severely restricted the sharing and circulation of data.A trusted way to realize the circulation of data is urgently needed.Privacy-preserving computation provides a feasible solution for achieving circulation of data in a trusted way.Privacy-preserving computation refers to a series of analysis and computation on data without compromising data privacy to ensure data circulation and integration in a "usable and invisible" manner.Secure multi-party computation is one of the privacy computing technologies with a solid cryptographic security theory foundation,which can provide privacy protection of the computation process and results.As a special case of secure multi-party computation,secure two-party computation(2PC)plays a fundamental role in the research of secure multi-party computation.The specific research in this thesis is as follows:(1)Since the security models considered in existing privacy protection schemes based on secure multi-party computation are not well suited to realistic scenarios,this thesis investigates publicly verifiable covert security(PVC)model with the goal of enhancing the practical security of the protocol.We point out a security flaw in the publicly verifiable covert secure protocol proposed in a prior work,where a malicious receiver can succeed in defaming the honest sender with high probability.We attribute this defamation to their Signed-OT extension scheme being incompatible with the PVC security model.To fix this,we propose a PVC security model with staged judgement.Compared to the original PVC security model,our security model is only slightly different and achieves strong defamation resistance.We propose a new compatible extension technique for Signed-OT and construct a secure 2PC protocol in the new PVC model.(2)Secure pattern matching(PM)problem is a hot application topic in the research field of 2PC.In this thesis,we mainly focus on the wildcard pattern matching(WPM)with more realistic significance.Previous studies introduce various approaches for the WPM problem but require at least a two-round protocol or computation cost linear to input length.Therefore,we focus on the round and computation complexity of the WPM.By combining oblivious transfer and secret sharing in a novel way,the secure wildcard pattern matching problem is reduced to the process of secret sharing and reconstruction.We propose a single-round secure WPM protocol under the semi-honest adversary model.Compared to existing secure WPM protocols,both theoretical and experimental results show that our protocol is more practical.