Research On Redactable Blockchain Technology Supporting Trapdoor Revocation And Limited Redaction

In recent years,blockchain technology has received extensive attention and development.The integrated application of the decentralized distributed ledger plays a vital role in new technological and industrial changes.The tamper-proof feature,as one of the major characteristics of blockchain,poses challenges for data security and regulation while ensuring the authenticity and reliability of data on the chain.Redaction blockchain which is able to eliminate malicious or illegal data on the chain promises to be an effective approach to addressing this challenge.Presently,the edit permissions of the redaction blockchain are issued by trusted third parties.The lack of regulations and constraints has created a potential for the abuse of this technology,posing an urgent need to achieve fine-grained management,accountability,and decentralization of edit permissions.Hence,based on the Chameleon Hash(CH)function,this paper examines the redaction blockchain technology supporting trapdoor undo and editing restrictions from aspects of the revocability,limits on redaction and duration of use of edit permissions and decentralized publishing.The following work has been completed:1.A function of Revocable Chameleon Hash with Limited number of Redaction(RCHLR)is proposed.The CH function is the main technology fulfilling redaction blockchain as a one-way hash function with a trapdoor.In the redaction blockchain,trapdoor possessors will have edit permissions.To achieve revocability and redaction limit of edit permissions,the RCHLR concept is proposed on the basis of the CH function and on that basis,a new redaction blockchain solution is given.The solution encompasses a mater trapdoor,subordinate trapdoor and the witness generated therefrom.Specifically,the subordinate trapdoor is used to edit data,the master trapdoor is used to revoke a subordinate door for the purpose of revoking edit permissions,and the witness can strictly limit the time of the redaction of the subordinate trapdoor to 1.The proposed solution is proven to be secure under the standard difficulty of problem solving.The theoretical analysis and simulation experiment show that compared with existing solutions supporting trapdoor revocability,the proposed solution has a certain practicality as it is superior in terms of security and smaller additionally introduced computational cost.2.A function based on the Epoch-based Revocable Chameleon Hash(ERCH)is proposed.To fulfill the revocability and time-limiting of edit permissions,the ERCH is proposed on the basis of the CH function,where an epoch is defined as a specific time period and the method to use ERCH to construct the redaction blockchain is described.ERCH makes a trapdoor timelimiting,which becomes invalid with changes in epoch.In this way,the purpose of revoking the trapdoor can be achieved.The security model of the solution is defined and specific instances are given.The proposed solution is proven to be secure under the standard difficulty of problem solving.Finally,the theoretical analysis and experiment show that compared with similar solutions,the proposed solution has a certain practicality as it is advantageous in terms of higher security and lower addition overhead.3.On the basis of the ERCH-based redaction blockchain,a decentralized trapdoor publishing protocol is proposed.To achieve decentralized publishing of edit permissions and eliminate the trusted third parties,a decentralized trapdoor publishing protocol is proposed.The protocol is able to select members of the regulatory body with changes in epoch with unpredictable randomness.Distributed key generation,secret sharing and other technologies are utilized to fulfill decentralized publishing of edict permissions.Secret sharing from the previous epoch is used to publish the trapdoor of the current epoch,generating the public epoch key and secret sharing of the corresponding trapdoor of the next epoch.Further,the secrets shared,as mentioned above,will be integrated and re-distributed to reduce the potential harms of leaked shared secrets.Further,the security and applicative scenarios of the protocol are further analyzed.