Cryptology ePrint Archive: Report 2013/606

Revocable quantum timed-release encryption

Dominique Unruh

Abstract: Timed-release encryption is a kind of encryption scheme that a recipient can decrypt only after a specified amount of time T (assuming that we have a moderately precise estimate of his computing power). A revocable timed-release encryption is one where, before the time T is over, the sender can "give back" the timed-release encryption, provably loosing all access to the data. We show that revocable timed-release encryption without trusted parties is possible using quantum cryptography (while trivially impossible classically).

Along the way, we develop two proof techniques in the quantum random oracle model that we believe may have applications also for other protocols.

Finally, we also develop another new primitive, unknown recipient encryption, which allows us to send a message to an unknown/unspecified recipient over an insecure network in such a way that at most one recipient will get the message.

Category / Keywords: cryptographic protocols / Quantum cryptography, timed-release encryption, everlasting security

Date: received 19 Sep 2013

Contact author: unruh at ut ee

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Version: 20130923:033730 (All versions of this report)

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