Research On Fair Payment And Regulatory Issues Of Bitcoin

As the representative of the digital currency,Bitcoin has become the focus of research in the contemporary.And it also exposed many problems while the Bitcoin system developed rapidly.First of all,the peer-to-peer payment method makes the transaction insecure and the fairness of the transaction process is challenged.Second,the anonymity of the Bitcoin system makes Bitcoin a tool for cybercrime.Therefore,how to ensure fairness in the payment process and how to effectively regulate Bitcoin transactions while protecting a user's privacy are two issues that need to be solved urgently for the continuous development of Bitcoin system.For the above two problems,the main contributions of this thesis are as follows:Firstly,we propose a fair Bitcoin payment scheme for digitized commodity.The scheme realizes a true “face to face” transaction.That is,when the merchant obtains bitcoins,the user gets the private key that decrypts the desired information.Based on the automatic execution feature of the Bitcoin scripts,once the user and the merchant submit the correct input,a Bitcoin transaction will be completed within a certain time and is unaffected by any participant.When a party aborts the protocol in advance,the scheme does not need to rely on a trusted third party or a recovery protocol,it can still guarantee the fairness of both parties.On the one hand,the user can get a refund,and on the other hand,the merchant will not suffer losses.In addition,we provide a detailed security analysis of the fair payment scheme and compare it with the existing schemes.Secondly,a regulation scheme for the Bitcoin transactions is proposed.By introducing a regulator into Bitcoin system,authentication of users' identities,monitoring of illegal transactions,and freezing of illegal accounts are achieved.By the cooperation between the tracking nodes and the user,the signature of a transaction is generated,and during the transaction,the tracking nodes can still track user's all accounts in the case of the user's anonymity.During the transaction verification,the tracking nodes can detect illegal accounts and reject transactions of illegal accounts.In the regulation of transactions,through cooperation between the regulator and the tracking nodes,On the one hand,the regulator can determine all accounts of the user according to the user's identity,and on the other hand,the regulator can locate the user's real identity through a certain Bitcoin transaction and associate all his accounts.This system not only protects the user's privacy,but also realizes the effective regulation of transactions.Finally,an improved secure multi-party ranking scheme is proposed.Then the scheme is applied to the Bitcoin regulation system.It achieves targeted regulation and improves the regulator's efficiency in the transactions' monitoring.In addition,compared with the original scheme,our scheme has higher efficiency.At last,the security of the improved secure multi-party ranking scheme is illustrated.