Timed-Release Public Key Based Authenticated Encryption

In this paper, we formally define a notion of timed-release public key based authenticated encryption (TR-PKAE). In addition to standard time-independent security properties (such as IND-CCA security for confidentiality and ciphertext/plaintext unforgeability), TR-PKAE introduces requirements such as timed-release receiver confidentiality (IND-RTR-CCA), which precludes the receiver from decrypting ciphertext before designated time, and ciphertext/plaintext unforgeability by the receiver itself for a future designated time among others. We propose a first provably secure TR-PKAE construction based on bilinear maps and prove the above security requirements in the random oracle model. Even though our protocol does not use digital signatures, receiver can still prove to a third party the message origin. The proposed protocol is compact, practical and efficient.