Secret And Verifiable Transaction On The Blockchain With Supervision And Its Application

From its inception to its development,the Internet has brought tremendous changes to human life.However,its inherent technical limitations have also brought many new network security problems,which have not been perfectly solved so far.Blockchain was born in 2008.This new type of architecture,which integrates multiple technologies such as distributed data storage,consensus mechanism,point-to-point transmission and encryption algorithms,can just complement some of the existing Internet architecture defects.Recently,the exploration and integration of blockchain in multiple industries and fields has gradually been accepted by the public and the government,and it is bound to cause global technological changes no less affected by the Internet.With the support of a series of favorable policies of the country,blockchain technology has taken root rapidly in China.At present,the use of blockchain to solve traditional industry problems and government affairs has become a major development path.However,the blockchain also has some inherent shortcomings.Especially with the global emphasis on privacy protection and the promulgation of a series of privacy regulations,privacy protection issues have become increasingly serious.With the implementation of blockchain technology,we are also facing challenges of supervision.Complete freedom from a certain regulation will inevitably lead to uncontrollable crime.In order to solve the problems of privacy protection and supervision in the traditional blockchain,and put it into practical application,this paper mainly proposes the following two novel,effective and efficient algorithms by using zero-knowledge proofs and combining with other cryptographic technologies such as encryption algorithms and commitment algorithms.The main work of this thesis is as follows.Aiming at the privacy flaws inherent in the blockchain,this thesis proposes a new digital trading system based on Zcash to support the supervision and complete privacy protection of traders' identity and transaction content.That is,our solution can achieve perfect identity and privacy of transaction content for all users except supervisors.The solution draws on the essence of Zcash's implementation mechanism,adopts zero-knowledge proof based on zk-SNARK to achieve privacy protection,and organically integrates the public key encryption mechanism,which intelligently realizes the coexistence between privacy and supervision,which cannot be solved by all of previous solutions.Finally,we evaluated the performance of the scheme on the domestic open source platform FISCO BCOS,and proved that our scheme is very private under supervision and effective in practical applications.Aiming at the difficulty of coexistence of privacy and supervision in the blockchain application process,this thesis combines some highly efficient zero-knowledge proofs and other cryptographic primitives to design a fully distributed,perfectly privacy-protected,globally verifiable,and supervisable application scheme based on blockchain.And we make a research and verification in a representative application scenario,electronic voting,so that each step in the voting process can provide complete privacy protection to the corresponding entity under supervision and support any validator to verify the entire process of voters and counters,while ensuring that their privacy is protected.Finally,we implemented and evaluated the practical performance of the scheme,and the results showed that there were no function,safety and efficiency bottlenecks in the actual application process.