Research On Blockchain Privacy Technology

The blockchain is the cutting-edge technology in the current security field.The blockchain is a data block chain structure arranged in chronological order.It is essentially a tamper-proof distributed database that uses cryptography to implement security of each link through decentralization.Blockchain has the characteristics of decentralization.tamper resistance,anonymity,open verifiable,traceable,and open source code.At present,in most blockchain platforms,any node can access all the data in the blockchain,so the privacy of the blockchain is particularly prominent,and it has become an important research topic in the field of blockchain.The current blockchain privacy technology mainly focuses on blockchain-based verifiable computing,blockchain data privacy,blockchain transaction address privacy,and blockchain transaction amount privacy.First,since blockchain,secure multiparty computing,and verifiable homomorphic secret sharing are all designed to solve the problem of how untrusted groups work together,the combination of blockchain and secure multiparty computing and verifiable homomorphic secret sharing has innate Advantage.Most existing homomorphic secret sharing and secure multi-party computing have the problem of a large number of communication rounds and a large amount of communication.However,in the blockchain environment,multiple rounds of communication and a large amount of communication data are bound to lead to a reduction in the efficiency of the algorithm itself and the blockchain platform.In addition,since the nodes in the blockchain are untrustworthy,a large amount of communication data will impose a heavy verification burden on the nodes.Therefore,it is important to study the homomorphism of low-level communication to verify secret sharing and secure multi-party computing for block-chain-based verifiable computing.Secondly,the existing blockchain-based applications generally have the problem of leaking data privacy and difficulty supporting homomorphic computing.Therefore,the research on the decentralized outsourcing computer system that is safe and efficient and supports homomorphic computing can effectively solve the problem that it is difficult to support homomorphic computing and privacy leakage in the blockchain application system.Finally,according to the accounting method,the blockchain can be divided into a UTXO-based blockchain and an account-based blockchain.Since the miners in the account blockchain need to update the dynamically changing balances in real time,the block chain balance hiding mechanism has certain difficulties.Therefore,the blockchain platform that currently provides the amount of hidden functionality is based on the UTXO blockchain,while the account-based blockchain platform records all transactions in clear text.Therefore,studying the blockchain balance hiding mechanism can make up for the lack of the hidden mechanism of the existing blockchain technology center.Starting from the privacy of blockchain,this paper studies the technology of three aspects:communication-synchronized secret sharing and secure multi-party computing,block-based decentralized outsourcing computer system and blockchain balance hiding mechanism.The main research results and innovations of this paper are as follows:(1)In the aspect of low-round communication verifiable secret sharing and secure multi-party computing,in order to cope with the problem that the blockchain is severely limited by the number of communication rounds and traffic,three verifiable cryptographic schemes are proposed based on the Shamir secret sharing algorithm.They are a round of communication to verify the first-order multiplicative homomorphic secret sharing scheme(NVHSS),a round of communication verifiable full homomorphic secret sharing scheme(NVFHSS)and a round of communication secure multi-party computing scheme(AntNest).(2)In the aspect of blockchain-based outsourcing computer system,in order to solve the problem of leaking privacy and difficult to support homomorphic calculation in blockchain application system,combined with the working principle of blockchain,NVHSS algorithm proposed in(1)and NVFHSS The algorithm proposes a decentralized outsourced computer system(DOC)that supports efficient homomorphic multiplication.In this machine,under the premise of ensuring data privacy,the decentralized node can provide users with verifiable outsourcing computing services,and can greatly reduce the data verification burden and storage space of users and server nodes.(3)In the privacy of blockchain transaction amount,combined with the scope certificate,Pedersen commitment and zero-knowledge proof and other cryptographic techniques,the blockchain balance hiding mechanism is proposed,including the anonymous coin-building process and the anonymous coin payment process.This mechanism is the first mechanism to realize the hidden function of blockchain balance,which makes up for the lack of the hidden mechanism of the existing blockchain technology center.On the one hand,the accounting process generates an anonymous currency account for the user,and deposits a certain amount of tokens from the open currency account to the anonymous currency account,which solves the problem of "where the anonymous currency comes from".On the other hand,the anonymous currency payment process implements a confidential transaction between anonymous currency accounts,hiding the transfer amount and user balance in a real-time,secure,and verifiable manner.