International Association for Cryptologic Research

International Association
for Cryptologic Research


Paper: General Certificateless Encryption and Timed-Release Encryption

Sherman S.M. Chow
Volker Roth
Eleanor G. Rieffel
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Abstract: 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.
  title={General Certificateless Encryption and Timed-Release Encryption},
  booktitle={IACR Eprint archive},
  keywords={public-key cryptography / security-mediated certificateless encryption, timed-release encryption, standard model},
  note={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. 14053 received 16 Jan 2008, last revised 23 Jun 2008},
  author={Sherman S.M. Chow and Volker Roth and Eleanor G. Rieffel},