Timed-Release and Key-Insulated Public Key Encryption

  • Jung Hee Cheon
  • Nicholas Hopper
  • Yongdae Kim
  • Ivan Osipkov
Part of the Lecture Notes in Computer Science book series (LNCS, volume 4107)


In this paper we consider two security notions related to Identity Based Encryption: Key-insulated public key encryption, introduced by Dodis, Katz, Xu and Yung; and Timed-Release Public Key cryptography, introduced independently by May and Rivest, Shamir and Wagner. We first formalize the notion of secure timed-release public key encryption, and show that, despite several differences in its formulation, it is equivalent to strongly key-insulated public key encryption (with optimal threshold and random access key updates). Next, we introduce the concept of an authenticated timed-release cryptosystem, briefly consider generic constructions, and then give a construction based on a single primitive which is efficient and provably secure.


timed-release authenticated encryption key-insulated encryption 


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  1. 1.
    Abdalla, M., Bellare, M., Rogaway, P.: The Oracle Diffie-Hellman Assumptions and an Analysis of DHIES. In: CT-RSA (2001)Google Scholar
  2. 2.
    An, J.H.: Authenticated Encryption in the Public-Key Setting: Security Notions and Analyses (2001),
  3. 3.
    Bellare, M., Desai, A., Pointcheval, D., Rogaway, P.: Relations Among Notions of Security for Public-Key Encryption Schemes. In: Krawczyk, H. (ed.) CRYPTO 1998. LNCS, vol. 1462, Springer, Heidelberg (1998)Google Scholar
  4. 4.
    Bellare, M., Goldwasser, S.: Encapsulated Key Kscrow. Technical report, MIT/LCS/TR-688 (1996)Google Scholar
  5. 5.
    Bellare, M., Palacio, A.: Protecting against Key Exposure: Strongly Key-Insulated Encryption with Optimal Threshold (2002),
  6. 6.
    Bellare, M., Rogaway, P.: Random Oracles are Practical: A Paradigm for Designing Efficient Protocols. In: ACM CCS (1995)Google Scholar
  7. 7.
    Blake, I.F., Chan, A.C.-F.: Scalable, Server-Passive, User-Anonymous Timed Release Public Key Encryption from Bilinear Pairing. In: ICDCS (2005)Google Scholar
  8. 8.
    Boneh, D., Franklin, M.: Identity Based Encryption from the Weil Pairing. In: CRYPTO (2003)Google Scholar
  9. 9.
    Boneh, D., Naor, M.: Timed Commitments. In: Bellare, M. (ed.) CRYPTO 2000. LNCS, vol. 1880, Springer, Heidelberg (2000)CrossRefGoogle Scholar
  10. 10.
    Boyen, X.: Multipurpose Identity Based Signcryption: A Swiss Army Knife for Identity Based Cryptography. In: Boneh, D. (ed.) CRYPTO 2003. LNCS, vol. 2729, Springer, Heidelberg (2003)CrossRefGoogle Scholar
  11. 11.
    Chen, L., Harrison, K., Soldera, D., Smart, N.: Applications of multiple trust authorities in pairing based cryptosystems. In: Davida, G.I., Frankel, Y., Rees, O. (eds.) InfraSec 2002. LNCS, vol. 2437, Springer, Heidelberg (2002)CrossRefGoogle Scholar
  12. 12.
    Cheon, J.H., Hopper, N., Kim, Y., Osipkov, I.: Timed-Release and Key-Insulated Public Key Encryption (2004), available from
  13. 13.
    Crescenzo, G.D., Ostrovsky, R., Rajagopalan, S.: Conditional Oblivious Transfer and Timed-Release Encryption. In: Stern, J. (ed.) EUROCRYPT 1999. LNCS, vol. 1592, Springer, Heidelberg (1999)Google Scholar
  14. 14.
    Dodis, Y., Katz, J.: Chosen-Ciphertext Security of Multiple Encryption. In: Theory of Cryptography Conference (2005)Google Scholar
  15. 15.
    Dodis, Y., Katz, J., Xu, S., Yung, M.: Key-Insulated Public Key Cryptosystems. In: Knudsen, L.R. (ed.) EUROCRYPT 2002. LNCS, vol. 2332, Springer, Heidelberg (2002)CrossRefGoogle Scholar
  16. 16.
    Dodis, Y., Katz, J., Xu, S., Yung, M.: Strong Key-Insulated Signature Schemes. In: Desmedt, Y.G. (ed.) PKC 2003. LNCS, vol. 2567, Springer, Heidelberg (2002)Google Scholar
  17. 17.
    Fujisaki, E., Okamoto, T.: Secure Integration of Asymmetric and Symmetric Encryption Schemes. In: Wiener, M.J. (ed.) CRYPTO 1999. LNCS, vol. 1666, Springer, Heidelberg (1999)Google Scholar
  18. 18.
    Garay, J., Pomerance, C.: Timed Fair Exchange of Arbitrary Signatures. In: Wright, R.N. (ed.) FC 2003. LNCS, vol. 2742, Springer, Heidelberg (2003)CrossRefGoogle Scholar
  19. 19.
    Garay, J.A., Pomerance, C.: Timed Fair Exchange of Standard Signatures. In: Financial Cryptography (2002)Google Scholar
  20. 20.
    Mont, K.H.M.C., Sadler, M.: The HP Time Vault Service: Exploiting IBE for Timed Release of Confidential Information. In: WWW (2003)Google Scholar
  21. 21.
  22. 22.
    Menezes, A., Okamoto, T., Vanstone, S.: Reducing elliptic curve logarithms to logarithms in a finite field. IEEE Transactions on Information Theory IT-39 5 (1993)Google Scholar
  23. 23.
    Mills, D.: Network Time Protocol (Version 3) Specification, Implementation. Technical Report 1305, RFC (1992)Google Scholar
  24. 24.
    Pederson, T.P.: A Threshold Cryptosystem Without a Trusted Party. In: Davies, D.W. (ed.) EUROCRYPT 1991. LNCS, vol. 547, Springer, Heidelberg (1991)Google Scholar
  25. 25.
    Rackoff, C., Simon, D.R.: Non-Interactive Zero-Knowledge Proof of Knowledge and Chosen Ciphertext Attack. In: Feigenbaum, J. (ed.) CRYPTO 1991. LNCS, vol. 576, Springer, Heidelberg (1992)Google Scholar
  26. 26.
    Rivest, R.L., Shamir, A., Wagner, D.A.: Time-lock Puzzles and Time-released Crypto. Technical report, MIT/LCS/TR-684 (1996)Google Scholar
  27. 27.
    Shamus Software Ltd. MIRACL: Multiprecision Integer and Rational Arithmetic C/C++ Library,
  28. 28.
    Syverson, P.F.: Weakly Secret Bit Commitment: Applications to Lotteries and Fair Exchange. In: Computer Security Foundations Workshop (1998)Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2006

Authors and Affiliations

  • Jung Hee Cheon
    • 1
  • Nicholas Hopper
    • 2
  • Yongdae Kim
    • 2
  • Ivan Osipkov
    • 2
  1. 1.Seoul National UniversityKorea
  2. 2.Twin CitiesUniversity of Minnesota 

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