New York University
While recent Timed-Release Encryption (TRE) schemes are implicitly supported by a CertificateLess Encryption (CLE) mechanism, the security models of CLE and TRE differ and there is no generic transformation from a CLE to a TRE. This paper gives a generalized model for CLE that fulfills the requirements of TRE. This model is secure against adversaries with adaptive trapdoor extraction capabilities for arbitrary identifiers, decryption capabilities for arbitrary public keys, and partial decryption capabilities. It also supports hierarchical identifiers. The authors propose a concrete scheme under their generalized model and prove it secure without random oracles, yielding the first strongly-secure smcle and the first TRE in the standard model.