IRIBE: Intrusion-resilient identity-based encryption

In order to limit the damage of key exposure for identity-based encryption, we propose a new paradigm called intrusion-resilient identity-based encryption (IRIBE) in this paper. Compared with key-insulated identity-based encryption and forward-secure identity-based encryption, IRIBE can achieve a stronger level of security. In our proposed scheme, the ciphertexts in any other time periods are secure even after arbitrarily many compromises of the base and the user, as long as compromises do not happen simultaneously. Furthermore, the intruder cannot decrypt the ciphertexts pertaining to previous time periods, even if it compromises the base and the user simultaneously. Therefore, our IRIBE scheme can greatly enhance the security of identity-based encryption. We also formalize the definition and the security notions of this paradigm. The proposed scheme is proven secure in the standard model.