Study On The Trading Pattern Of Secure Distributed E-commerce

The rapid growth of Internet has been stimulating the global development of E-commerce. Due to centralization of data, computing and trust, traditional E-commerce has potential performance, scalability and security problems, which would be solved by the help of research on distributed E-commerce. There have been a lot of research work in distributed services, distributed storage and search, P2P trust model, etc., while distributed trading pattern is scarcely studied. On the other hand, one single distributed architecture cannot satisfy all the requirements of data, computing and trust distribution. In this thesis, by designing schemes for three key processes, secret merchandise information query, E-auction and fair trading, we propose a trading pattern of distributed E-commerce based on hybrid architecture. The main innovative results are as follows:1. A hardware-based private information retrieval scheme is proposed. By partially reshuffling previously accessed items in each round, instead of frequently reshuffling the whole database, the scheme makes better use of shuffled database copies and achieves the lowest computation overhead among state-of-art schemes. Meanwhile the scheme doesn't increase the response time and communication cost, and is suitable for databases of any size. Therefore it has great practical value and is useful to construct privacy preserving merchandise information query schemes.2. Two distributed E-auction schemes are proposed. In both schemes, bidders join the auction by submitting their bid-chains, while other peers (auxiliary auctioneers) in the P2P network compute results instead. The proposed distributed proxy open auction protocol runs in a similar way to other ascending open auctions, but differs in that it allows asynchronous bidding and prevents losing bids from complete exposure. Moreover, a distributed sealed-bid auction protocol is proposed. The winning price and winner is resolved by the seller and auxiliary auctioneers together. All the privacy of losing bids and bidders is fully protected during the whole process even if there are collusions of some curious participants.3. A fair contract signing protocol and a fair exchange protocol are proposed. We define a more practical model for a previous fair contract signing protocol by distinguishing signing processes and signing users, analyze potential attacks to the original protocol in the new model, and then propose an improved protocol which is also asynchronous and optimistic. The proposed protocol can resist the attacks and guarantee fairness without increasing the number of communication rounds. On the other hand, a gradual optimistic fair exchange protocol is presented. Each party can stop releasing the rest secret shares after occurrence of cheating, which could be detected with high probability. A threshold decryption group is involved only in case of exception in the last exchange round. The proposed protocol doesn't rely on equal computing power assumption or a trusted third party to guarantee fairness, and also has lower communication complexity than that of previous gradual release schemes.4. A new trading pattern of secure distributed E-commerce, TPSDE, and its prototype system are established. TPSDE integrates two distributed architecture, and is mainly composed of three parts:secret merchandise information query, distributed E-auction and optimistic fair trading. The basic merchandise information is distributed among some servers, which can provide privacy preserving merchandise information query service using private information retrieval scheme; whereas more onerous computing, E-auction and fair trading, is distributed among peers to protect the privacy of trading information. A prototype system is devised to further validate the feasibility of TPSDE.