Research On Anonymity And Key Management Of Bitcoin

Cryptographic currency is more and more important in the digital payment field with the development of the Internet technology.As the most successful cryptographic currency in history,Bitcoin is characterized by decentralization.It has received an astonishing amount of attention and has been widely accepted.Although Bitcoin system worked well,it still has many problems to be solved,lacking of strong theoretical support.This directly influences the development and application of Bitcoin.The anonymity of Bitcoin and how to manage private keys of Bitcoin are the two issues which influence users most.Bad anonymity will leak the privacy of users.And how safe the private keys are means how safe the users' property will be,once the private key of Bitcoin is lost or has been stolen,the Bitcoin will never be recovered and the user will lose his money forever.Therefore,we will research on the anonymity issues and the key management issues of Bitcoin,the work are done as follows in this paper:Firstly,this paper studied the basic principle of the Bitcoin and analyzed the exiting problems,focusing on the anonymity issues of Bitcoin and the key management issues.The existing schemes to improve the anonymity of the Bitcon are analyzed and compared,and the existing key management schemes for Bitcoin are introduced and analyzed.Secondly,this paper proposed a model of Bitcoin payment system which is based on a proxy while a solution which is based on blind signature technique is proposed.The feature of decentralization in Bitcoin system is based on a public ledger called block chain.All the transaction information is recorded in the block chain which may leak users' information,compromising the feature of anonymity.Meanwhile to avoid double-spending,the payment will be confirmed after some blocks after the transaction.The long waiting time reduces the efficiency of the Bitcoin payment system.To solve these problems,this paper proposed a model of Bitcoin payment system which is based on a proxy.And a solution which is based on blind signature techniques is proposed.The introduction of a proxy can increase the efficiency of the payment because the payment doesn't need time to be confirmed.And the system protects users' privacy to get better anonymity.Finally,for the secure key management issues,a centralized threshold signature system is proposed for the Bitcoin because in many cases a dealer is necessary to distribute secret shares for an existing key in Bitcoin system.In addition,this paper improved the existing distributed threshold signature system proposed by Goldfeder,so that it can be applied in a nt),(scheme with better efficiency.Besides,this paper described the application of threshold signature system in the key management issues for Bitcoin and gave the implementation in different cases.