Research On Lattice-based Blockchain Security And Privacy Protection Technology

Blockchain technology is a new distributed infrastructure and computing paradigm.It has great development potential and broad application prospects,therefore blockchain has received widespread attention.Though blockchain technology is booming,it is also facing severe challenges in terms of security and privacy protection.Not only that.under quantum attack,existing cryptographic algorithms will be not safety or be compromised.Obviously,with the continuous development of quantum computing technology,a large number of cryptographic components which used in the blockchain technology,is facing serious potential quantum computing threats.Therefore,it is important to consider the quantum security of the blockchain technology.In fact,to build blockchain security and privacy protection scheme has become an important part of promoting the application of blockchain technology and long-time security.As a typical post-quantum cryptography,lattice-based cryptography has achieved rapid development in recent years.In order to achieve the quantum security of the blockchain in the digital currency,we study the blockchain transaction authentication and its privacy protection over lattices in this thesis and the main work is described as follows:(1)A blockchain transaction authentication scheme is designed over lattices.To improve the security of the blockchain and also save the storage cost of the blockchain wallet,a blockchain transaction authentication model suitable for hierarchical deterministic wallets has been established,and a fixed-dimensional lattice-based delegation algorithm is used to generate the user's sub-key pairs.An anti-quantum attack blockchain transaction authentication scheme is designed over lattices.The analysis results show that based on the difficult assumption of the Smallest Integer Solution(SIS)Problem,the authentication scheme is proved to be existentially unforgeable under the standard model;as the sub-key pairs size is consistent with the seed key size,compared with the method of generating sub-key pairs based on the bonsai tree principle,the length of the sub-public and secret key is compressed by 50%and 75%,respectively,and the length of the transaction signature secret key is compressed by 75%.(2)A blind coin mixing scheme is designed over lattices.To implement the blockchain privacy protection,and prevent the malicious disclosure of user privacy and coin theft by the coin mixing service providers,the blind signature and the coin mixing mechanism are combined to design a blind coin mixing scheme.The scheme effectively eliminates malicious attacks by coin mixing service providers.More precisely,a blind signature scheme without restart is designed over lattices firstly.Then,based on the lattice-based blind signature scheme,a blind coin mixing scheme is designed.The proposed scheme effectively prevents malicious coin mixing service providers from leaking user privacy,and realizes the protection of user transaction privacy.Compared with blind coin mixing scheme,the scheme has advantages in anti-quantum attack and anti-theft coin attack.A simulation implementation of the lattice-based blind signature scheme in the scheme is given by using Java programming language.The experimental results show that the scheme can achieve higher computational efficiency.