Efficient Timed-release Public-key Encryption
Giovanni Di Crescenzo, Rafail Ostrovsky and S. Rajagopalan
Abstract: We consider the problem of sending messages ``into the future'', which recently received considerable attention in the literature. Previous constructions for this task were either based on heuristic assumptions or did not provide anonymity to the sender of the message. In the public-key setting, we present an efficient secure time-release encryption scheme using a ``time server'' which inputs the current time into the system. The server has to only interact with the receiver and never learns either the sender's identity or the deadline. The scheme's computational and communicational cost per request are logarithmic in the time parameter. The construction is based on a novel ``conditional oblivious transfer'' protocol, which may be of independent interest.
comment: Appeared in Proceedings of (EUROCRYPT-99) Springer Verlag.
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