Revocable Policy-Based Chameleon Hash for Blockchain Rewriting

Policy-based chameleon hash is a useful primitive for blockchain rewriting systems. It allows a user to create a mutable transaction associated with an access policy, whereas a modifier who possesses sufficient rewriting privileges from a trusted authority satisfying the access policy can rewrite the mutable transaction. However, it lacks a revocation mechanism. The modifiers can always rewrite the mutable transactions even if their given rewriting privileges are compromised. In this work, we introduce revocable policy-based chameleon. The property of revocation allows some modifiers' rewriting privileges to be revoked, regardless of whether their rewriting privileges are compromised or not.