CROSS: Supervised Sharing of Private Data over Blockchains

The transparent property of the blockchain guarantees the immutability of the data on the chain, but it can lead to violations of data privacy protection. On the other hand, absolute anonymity will make it difficult for the government to supervise the encrypted content stored on the chain. Moreover, it is inconvenient for the data owners to delegate their decryption authority to others. In order to solve the problem of data privacy concern and supervision in the current blockchain, we propose a supervised data sharing model called CROSS, which combines the proxy re-encryption mechanism with the tree key distribution mechanism. The model realizes the hierarchical supervision and horizental sharing of private data on the blockchain, which effectively improves the privacy of the blockchain while taking into account security. Consideration should be given to some potential attacks and corresponding defenses against our proposed model.