Paper 2008/023

General Certificateless Encryption and Timed-Release Encryption

Sherman S. M. Chow, Volker Roth, and Eleanor G. Rieffel


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, decryption capabilities for arbitrary public keys, and partial decryption capabilities. It also supports hierarchical identifiers. We propose a concrete scheme under our generalized model and prove it secure without random oracles, yielding the first strongly-secure security-mediated CLE and the first TRE in the standard model. In addition, our technique of partial decryption is different from the previous approach.

Available format(s)
Public-key cryptography
Publication info
Published elsewhere. This is the full version of the paper to appear in Security and Cryptography for Networks, 6th International Conference, SCN 2008, Amalfi, Italy, September 10-12, 2008.
timed-release encryptionstandard model
Contact author(s)
schow @ cs nyu edu
2008-06-23: last of 6 revisions
2008-01-22: received
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Creative Commons Attribution


      author = {Sherman S. M.  Chow and Volker Roth and Eleanor G.  Rieffel},
      title = {General Certificateless Encryption and Timed-Release Encryption},
      howpublished = {Cryptology ePrint Archive, Paper 2008/023},
      year = {2008},
      note = {\url{}},
      url = {}
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