In the paper "How to build time-lock encryption", the authors give a theoretical solution to build time-lock encryption using multi-linear based witness encryption and blockchain. However, an instantiation of the construction is unfeasible to build because of the inefficiency of multi-linear maps.

So, if witness encryption based on multi-linear maps can't provide the efficiency required for the time-lock encryption, what alternatives are there? There are witness encryption schemes built from indistinguishable obfuscation, could time-lock encryption also be implemented using that?

  • 2
    $\begingroup$ I presume you mean this paper? Please always link and / or uniquely reference papers. Could you take another look at your final sentence? The first to last sentence is also incomplete. Please edit so we can reopen the question. $\endgroup$
    – Maarten Bodewes
    May 30, 2019 at 18:37
  • $\begingroup$ What makes you think, that indistinguishability obfuscation can be implemented more efficiently than multi linear maps? I think you can construct them vice versa, if you throw in fully homomorphic encryption. On a very, very rough level, it is different sides of the same coin. $\endgroup$
    – tylo
    Jul 4, 2019 at 14:49

1 Answer 1


Time-lock puzzles can be built from indistinguishability obfuscation through succinct randomised encodings: see the work of Bitansky et al. [BGJ+,BGL+] for more details.

[BGJ+]: Bitansky et al. Time-Lock Puzzles from Randomized Encodings. ITCS'16

[BGL+]: Bitansky et al. Succinct Randomized Encodings and their Applications. STOC'15


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