One-Time Chameleon Hash Function and Its Application in Redactable Blockchain

A new cryptographic primitive called a one-time chameleon Hash function is proposed for the first time. For this new primitive, two pre-images of the same Hash value (i.e. one collision) will not expose any trapdoor information, while three pre-images of the same Hash value (i.e. two collisions) will expose some trapdoor information, but it is enough to cause some serious security hazards. An efficient one-time chameleon Hash function scheme is constructed based on the classical RSA hard problem. Then its security is proved based on the RSA assumption in the random oracle model. By using this one-time chameleon Hash function scheme, a redactable blockchain scheme is further implemented efficiently, which only allows one redaction at most for each block, and any second redaction of the block will result in the penalty of the blockchain crash. Effective governance of blockchain is the key area of cyberspace security governance, and the redactable blockchain constitutes the most core technology of blockchain supervision and governance. The redactable blockchain scheme proposed in this paper has two characteristics of high efficiency and redacting restrictions compatible with the practical demand. So it is expected to provide a powerful technical method for blockchain supervision (especially for the post-governance of harmful data stored on the chain).