Certificateless Public Key Cryptosystem And Application In E-commerce

With the rapid development of information technology, the e-commerce which established upon internet has gradually became a new mode in people’s business activities. The way of people’s production and life has been changed by e-commerce activity, which not only provides a convenient service, but also brings the more prominent information security issues. How to ensure the e-commerce payment security has become a top priority problem to be solved among the consumers and businesses. Digital signature is an important technology which provides the authenticity, integrity and undeniability of the information, playing an important role in e-commerce. Proxy signature is a special digital signature, which is more and more widely applied in e-commerce, e-payment, grid computing, mobile agent and other fields.After proposed in 2003 Asiacrypt, certificateless public cryptosystem(CL-PKC) has been received a great deal of attention, It eliminates the exist defects of traditional public key cryptosystems based on PKI(Public Key Infrastructure) and ID-PKC(Identity-based Public Key Cryptography), meanwhile, solves the problem of the use of certificate and key escrow. Therefore, combining the good advantage of CL-PKC and proxy signature, it should provide a better guarantee for the safety of e-cash payment in e-commerce. There are many research contents in CL-PKC, in this dissertation, we mainly discuss certificatelesss digital signature and proxy signature, as well as the application of certificatelesss proxy signature in e-commerce.In this dissertation, we firstly review the research background and the current development of certificatelesss digital signature and proxy signature, introduce some basic concepts of cryptography, digital signature and proxy signature. Then we introduce the formal definition and security model of three protocols, which are included in CL-PKC. Followed by an analysis of a certificateless signature scheme, we give a security and efficient improved scheme, and based on the improved scheme, a secure certificateless proxy signature scheme is proposed. Finally, we discuss the application of certificateless proxy signature in e-commerce, and build a secure e-cash payment system model based on certificateless proxy signature.The main results of this thesis are as follows:(1) Studying a certificateless signature scheme deeply and analyzing the security of an efficient certificateless signature scheme, which is proposed by Li et al. The analysis points out that it can not resist public key replacement attack and the malicious KGC attack. In response to these defects, we propose an improved scheme, which is prove to be secure in the random oracle model under the difficult assumption of the DLP and CDHP, and is not forged under adaptive chosen message attack. Through efficiency analysis, new scheme’s computational cost is less than other schemes, the efficiency is significantly improved.(2) Based on the improved certificateless signature scheme, we design a certificateless proxy signature scheme, which not only satisfies some security properties, such as unforgeability, verifiability, undeniability, distinguishability, identifiability and controllability, but also the computational complexity is reduced, and has a high efficiency compared with the other existed schemes, at the same time has a good application value in e-commerce.(3) Applying certificateless proxy signature scheme to e-commerce, we construct a secure e-cash payment system model based on certificateless proxy signature. The model not only eliminates the dependence on the certificate, but also does not exist key escrow problem, meanwhile achieving the e-cash’s no double-spending and no-tracking for agent and merchant, has both theoretical and practical value.