Provably secure timed-release public key encryption

Jung Hee Cheon, Nick Hopper, Yongdae Kim, Ivan Osipkov

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


A timed-release cryptosystem allows a sender to encrypt a message so that only the intended recipient can read it only after a specified time. We formalize the concept of a secure timed-release public-key cryptosystem and show that, if a third party is relied upon to guarantee decryption after the specified date, this concept is equivalent to identity-based encryption; this explains the observation that all known constructions use identity-based encryption to achieve timed-release security. We then give several provably-secure constructions of timed-release encryption: a generic scheme based on any identity-based encryption scheme, and two more efficient schemes based on the existence of cryptographically admissible bilinear mappings. The first of these is essentially as efficient as the Boneh-Franklin Identity-Based encryption scheme, and is provably secure and authenticated in the random oracle model; the final scheme is not authenticated but is provably secure in the standard model (i.e., without random oracles).

Original languageEnglish (US)
Article number4
JournalACM Transactions on Information and System Security
Issue number2
StatePublished - May 1 2008


  • Authenticated encryption
  • Key-insulated encryption
  • Timed-release


Dive into the research topics of 'Provably secure timed-release public key encryption'. Together they form a unique fingerprint.

Cite this