Research On Storage And Access Control Mechanism In Electronic Evidence Based On Blockchain

With rapid development of the information age,the proportion of electronic evidence involved in judicial cases has been rising,and the importance of electronic evidence is increasingly prominent.In the real judicial process,there are strict requirements put forward for the authenticity identification,tamper proof storage and legal sharing methods of electronic evidence,bringing many security challenges.However,the traditional solutions rely too much on the third-party centralized organization,and lack of secure sharing and credibility verification methods for electronic evidence,which can not meet the above requirements.If these problems can not be solved,the legal force of electronic evidence will be seriously reduced.Blockchain technology has the characteristics of decentralization and tamper proof,which provides a new method for the storage and extraction of electronic evidence.Aiming at the problem of secure storage and sharing of electronic evidence,this paper proposes a blockchain-based structure of secure storage and access for electronic evidence in judicial scene,establishes a storage access control model under this structure and designs the corresponding storage access control algorithms and protocols.In this scheme,multi-entity cooperation is allowed to store evidence,and a zero-knowledge identity authentication algorithm is applied to achieve access control and data sharing.The main contributions of this paper are as follows:(1)A blockchain-based structure of secure storage and access for electronic evidence in judicial scene is established.This structure is composed of a judiciary alliance chain called Jud Chain and a storage chain for electronic evidence named Evi Chain to realize the storage separation of transaction and evidence.This structure has specific and complete node authentication scheme,block generation process and detailed design of consensus algorithm,and its complete security and superior performance have been proved in relevant analysis and experiments.(2)An authentication algorithm based on zero-knowledge proof is proposed.Based on the theory of zero-knowledge proof,this paper constructs an identity authentication model and designs an authentication scheme,enabling multiple nodes to authenticate the identity of the on-chain requester cooperatively.In order to save the time and communication cost caused by data interaction,the algorithm achieves non-interactive form through a short random string shared by prover and verifier.Relevant experiments and analysis show the performance superiority of this scheme,and the honest prover and verifier can correctly complete the two-way authentication without disclosing any private data.(3)A storage and access control scheme for electronic evidence based on the secure structure is designed.Firstly,this scheme improves the typical ciphertext policy attribute-based encryption algorithm in a collaborative way on chain and off chain,allowing multiple entities to cooperate to encrypt and store the related data.Then,in the form of two levels of access control,the requester decrypts the evidence metadata through the authentication algorithm on the chain,and then matches the access policy to obtain the complete evidence off the chain.The analysis shows that the protocol can realize the secure sharing of judicial data and the legitimate control of access rights.The work of this paper can ensure the authenticity,integrity,privacy and traceability of electronic evidence while realizing the storage and sharing of it.Compared with other schemes,the proposed scheme achieves higher and more comprehensive security,has non repudiation and ensures the security of known keys,and can effectively resist collusion,camouflage,replay and man-in-the-middle attacks.Experiments show that the scheme can meet the storage and access requirements of electronic evidence in judicial context with high performance and efficiency.