PDP algorithm is used to realize the consistency audit technology of off chain data, and realize the credible and fair audit function of off chain data on the premise that the auditor does not hold the audited data object.
The technology of blind signature, zero knowledge proof, verifiable secret sharing and Merkle tree is comprehensively used to realize a decentralized identity management system supporting privacy protection, allowing users to operate anonymously on the blockchain. At the same time, controlled traceability and revocation of illegal identities are allowed.
The controlled deletion and modification of data on the chain can be of different granularity. The rollback of the whole blockchain is a forked operation scheme. The modification at the block level is realized by using the trapdoor hash function. The modification at the transaction level needs to pay attention to the whole transaction tree.
The blockchain research center of Peking University is a scientific research institution that launched blockchain research earlier in China. In recent years, it has undertaken many projects such as nuclear high-tech base, 863 and key research and development plans for Cyberspace Security, and deeply participated in blockchain related international communities such as super ledger, Ethereum classic and cloud security chain alliance. The research team has published more than 20 high-level papers related to blockchain in recent three years, The project research team won the first prize in 2018 longhash global blockchain competition and other blockchain related awards, and the key technologies were applied in blockchain platforms such as Baidu super chain and Huawei cloud blockchain service.