International Association for Cryptologic Research

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Paper: Scalable, Server-Passive, User-Anonymous Timed Release Public Key Encryption from Bilinear Pairing

Authors:
Ian F. Blake
Aldar C-F. Chan
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URL: http://eprint.iacr.org/2004/211
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Abstract: We consider the problem of sending messages into the future, commonly known as timed release cryptography. Existing schemes for this task either solve the relative time problem with uncontrollable, coarse-grained release time (time-lock puzzle approach) or do not provide anonymity to sender and/or receiver and are not scalable (server-based approach). Using a bilinear paring on any Gap Diffie-Hellman group, we solve this problem by giving a scalable, server-passive and user-anonymous timed release public-key encryption scheme which allows precise absolute release time specifications. Unlike the existing server-based schemes, the trusted time server in our scheme is completely passive --- no interaction between it and the sender or receiver is needed; it is even not aware of the existence of a user, thus assuring the anonymity of both the sender and receiver of a message and the privacy of the message. Besides, our scheme also has a number of desirable properties including self-authenticated time-bound key updates, a single form of update for all receivers, simple public-key renewal and key insulation, making it a scalable and appealing solution.
BibTeX
@misc{eprint-2004-12183,
  title={Scalable, Server-Passive, User-Anonymous Timed Release Public Key Encryption from Bilinear Pairing},
  booktitle={IACR Eprint archive},
  keywords={timed release encryption, bilinear pairing, identity-based encryption, anonymity},
  url={http://eprint.iacr.org/2004/211},
  note={- aldar@comm.utoronto.ca 12670 received 25 Aug 2004, last revised 9 Sep 2004},
  author={Ian F. Blake and Aldar C-F. Chan},
  year=2004
}