Blockchain Privacy Protection Method Based On Threshold Cryptography

Blockchain does not contain any form of third-party intermediary,so it has become the carrier of value internet.It can effectively connect Internet of things,5g,AI,big data and other technologies,and plays an important role in the new infrastructure.Bank,insurance,medical and other industries have proposed to use of blockchain technology to solve their difficulties.However,due to the underlying database were public,the user's identity and transaction amount can be seen at a glance,and the serious leakage of privacy,few enterprise level products have been implemented except for the blockchain certificates which are approved by the court.In order to protect the privacy of blockchain,this paper proposes blockchain privacy protection method based on threshold cryptography,and gives the model and related algorithm.The symmetric cryptography is used to encrypt the original transaction of blockchain,the threshold cryptography is used for access control,and the threshold signature is used for consensus.The main work of this paper is as follows:(1)This paper proposes a access control method to protect blockchain privacy based on threshold encryption algorithm.First,the original transaction transactions are divided into different sets according to the different access rights.The transaction transactions in different sets are encrypted with different symmetric keys.The transaction transactions in the set are encrypted with the same symmetric key.The blockchain only stores the encrypted transactions,and the original transaction transactions are not accessible.Secondly,the symmetric key is encapsulated into N copies,and the elliptic curve encryption algorithm is used to distribute the encapsulated key fragments to authorized users.Each authorized user keeps a key fragment.Finally,the authorized access users use the distributed threshold key recovery technology to safely calculate the symmetric key in the public network,and then get the transaction transactions' plaintext.Only ? or more authorized access users are online at the same time,the symmetric key can be recovered.When there are less than ? authorized access users,the symmetric key cannot be recovered.The experimental results show that the cost of storage capacity of the transaction transactions in this paper is lower than the transactions based on ring signature technology,and the transaction generation efficiency generating transaction is higher than the Zcash.(2)This paper proposes a blockchain consensus mechanism based on threshold signature algorithm.First,authorized users sign the verified privacy transaction transactions and make security endorsement.Secondly,the consensus node votes on the privacy transaction.There are four rounds of voting.The first round voting pass rate threshold is set to50%.Only when the vote is passed can the next round of voting be carried out.After each round of voting,the threshold is increased by 10%.The fourth round voting pass rate is set to 80%.The consensus node adds the trusted nodes to the trust node set and only accepts the vote send by trusted nodes Centralized node voting.Finally,the consensus node writes the transaction transactions voted passed into the blockchain.Experimental results show that the computation time cost of the consensus mechanism based on threshold signature algorithm is proportional to the number of trusted nodes.