Abstract
Time-lock puzzles allow one to encapsulate a message for a pre-determined amount of time. The message is required to be concealed from any algorithm running in parallel time less than the pre-determined amount of time. In the previous works, the security of time-lock puzzles was formalized in an indistinguishability manner. However, it is unclear whether it directly meets the security requirements of time-lock puzzles. In this work, we define semantic security for time-lock puzzles, which captures the security requirements of the time-lock puzzle more directly. We consider three computational restrictions of an adversary and see how the security relationship changes. At first, in the traditional setting, we observe that it is difficult to prove that the semantic security implies the indistinguishability, same as the opposite implication. Secondly, in a slightly relaxed setting, we show that it is possible to prove that the semantic security implies the indistinguishability. By contrast, we observe that it is difficult to prove the opposite implication. Thirdly, in the more relaxed setting, we show that it is possible to prove that semantic security is equivalent to the indistinguishability. This shows that an indistinguishability meets the security requirements of time-lock puzzles in a certain restriction.
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References
Brakerski, Z., Döttling, N., Garg, S., Malavolta, G.: Leveraging linear decryption: rate-1 fully-homomorphic encryption and time-lock puzzles. In: Hofheinz, D., Rosen, A. (eds.) TCC 2019. LNCS, vol. 11892, pp. 407–437. Springer, Cham (2019). https://doi.org/10.1007/978-3-030-36033-7_16
Bitansky, N., Goldwasser, S., Jain, A., Paneth, O., Vaikuntanathan, V., Waters, B.: Time-lock puzzles from randomized encodings. In: Proceedings of the 2016 ACM Conference on Innovations in Theoretical Computer Science, Cambridge, MA, USA, 14–16 January 2016, pp. 345–356 (2016)
Bitansky, N., Garg, S., Lin, H., Pass, R., Telang, S.: Succinct randomized encodings and their applications. In: Proceedings of the Forty-Seventh Annual ACM on Symposium on Theory of Computing, STOC 2015, Portland, OR, USA, 14–17 June 2015, pp. 439–448 (2015)
Dwork, C., Naor, M.: Pricing via processing or combatting junk mail. In: Brickell, E.F. (ed.) CRYPTO 1992. LNCS, vol. 740, pp. 139–147. Springer, Heidelberg (1993). https://doi.org/10.1007/3-540-48071-4_10
Ephraim, N., Freitag, C., Komargodski, I., Pass, R.: Non-malleable time-lock puzzles and applications. IACR Cryptol. ePrint Arch. 2020:779 (2020)
Garg, S., Gentry, C., Sahai, A., Waters, B.: Witness encryption and its applications. In: Symposium on Theory of Computing Conference, STOC 2013, Palo Alto, CA, USA, 1–4 June 2013, pp. 467–476 (2013)
Liu, J., Jager, T., Kakvi, S.A., Warinschi, B.: How to build time-lock encryption. Des. Codes Cryptogr. 86(11), 2549–2586 (2018). https://doi.org/10.1007/s10623-018-0461-x
May, T.C.: Timed-release crypto (1993)
Mahmoody, M., Moran, T., Vadhan, S.: Time-lock puzzles in the random oracle model. In: Rogaway, P. (ed.) CRYPTO 2011. LNCS, vol. 6841, pp. 39–50. Springer, Heidelberg (2011). https://doi.org/10.1007/978-3-642-22792-9_3
Malavolta, G., Thyagarajan, S.A.K.: Homomorphic time-lock puzzles and applications. In: Boldyreva, A., Micciancio, D. (eds.) CRYPTO 2019. LNCS, vol. 11692, pp. 620–649. Springer, Cham (2019). https://doi.org/10.1007/978-3-030-26948-7_22
Rivest, R.L., Shamir, A., Wagner, D.A.: Time-lock puzzles and timed-release crypto. Technical report, Cambridge, MA, USA (1996)
Acknowledgements
A part of this work was supported by NTT Secure Platform Laboratories, JST OPERA JPMJOP1612, JST CREST JPMJCR14D6, JSPS KAKENHI JP16H01705, JP17H01695, JP19J22363, JP20J14338.
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Hiraga, D., Hara, K., Tezuka, M., Yoshida, Y., Tanaka, K. (2021). Security Definitions on Time-Lock Puzzles. In: Hong, D. (eds) Information Security and Cryptology – ICISC 2020. ICISC 2020. Lecture Notes in Computer Science(), vol 12593. Springer, Cham. https://doi.org/10.1007/978-3-030-68890-5_1
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DOI: https://doi.org/10.1007/978-3-030-68890-5_1
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