Fair Online Auction System On Bitcoin

Online auction is an important application scenario for secure multiparty computation.According to the bidding rules,online auction can be divided into many kinds,such as the English auction,the Dutch auction,the Sealed auction,the Vikrey auction and so on.In the case of Sealed auction,users have high demand for data privacy,each participant's price should be protected from the others.What's more,the website,who acts as a third party for computing,is also need to be taken into account,for he may reveal the data or modify the data in malicious behavior.However,fairness is another important attribute that one must consider when designing a online auction system,to guarantee that all participants can get the correct output.The existing secure computation models cannot provide completely fairness with the absent of the trusted third party.So how to guarantee fairness and security is still a serious problem to be solved.In this paper,we present a fair and secure multi-party computing protocol based on Bitcoin to solve the fairness problem in the secure multi-party computation,and the agreement is applied to the online bidding agreement.This paper mainly completes the following work: first,to improve the standard time-controlled commitment agreement,in this paper,a time-controlled commitment protocol based on Bitcoin is proposed,which is associated with the signature and verification information of the bit currency,which guarantees that the promise information is sent at the same time when the deposit is paid,and the information of the open commitment is sent when the deposit is retrieved.According to the real application scenario of online bidding,a fair online bidding agreement is constructed based on the time-controlled commitment protocol to ensure that the honest user can finally get the output result or obtain the monetary compensation in the form of Bitcoin.When a malicious user does not send open information in the open phase,the honest user cannot get the result,the malicious user pays the deposit will be forced to transfer to the honest user;Finally,the fair online bidding system is designed and implemented.That is,the mutual distrust of the n participants in the bidding activities,everyone has a secret price s,together to calculate the highest price.By paying the deposit at the beginning of the agreement,all participants are encouraged to execute the agreement honestly,and the deposit will be compensated to the other person if a participant has malicious behavior that results in an unfair output of the agreement.Compared with other fair computing schemes,the advantage of this scheme is that it does not require for a trusted third parties,and does not require for the majority of participants to be honest,it also supports the scenario of two or more participants,and the computational complexity is based on block-chain technology,however the number of interactions is proportional to the number of participants.The scheme guarantees fairness and security and is practical in practice.