Public-Key Cryptosystems Resilient to Continuous Tampering and Leakage of Arbitrary Functions

We present the first chosen-ciphertext secure public-key encryption schemes resilient to continuous tampering of arbitrary (efficiently computable) functions. Since it is impossible to realize such a scheme without a self-destruction or key-updating mechanism, our proposals allow for either of them. As in the previous works resilient to this type of tampering attacks, our schemes also tolerate bounded or continuous memory leakage attacks at the same time. Unlike the previous results, our schemes have efficient instantiations, without relying on zero-knowledge proofs. We also prove that there is no secure digital signature scheme resilient to arbitrary tampering functions against a stronger variant of continuous tampering attacks, even if it has a self-destruction mechanism.