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McFly: Verifiable Encryption to the Future Made Practical.

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posted on 2024-03-20, 10:31 authored by Nico DöttlingNico Döttling, Lucjan HanzlikLucjan Hanzlik, Bernardo Magri, Stella WohnigStella Wohnig

Blockchain protocols have revolutionized the way individuals and devices can interact and transact over the internet. More recently, a trend has emerged to harness blockchain technology as a catalyst to enable advanced security features in distributed applications, in particular fairness. However, the tools employed to achieve these security features are either resource wasteful (e.g., time-lock primitives) or only efficient in theory (e.g., witness encryption). We present McFly, a protocol that allows one to efficiently ``encrypt a message to the future'' such that the receiver can decrypt the message almost effortlessly. Towards this goal, we design and implement a novel primitive we call signature-based witness encryption and combine it with a BFT blockchain (or a blockchain finality layer) in such a way that the decryption of the message can be piggybacked on the tasks already performed by the blockchain committee, resulting in almost-for-free decryption. To demonstrate the practicality of the McFly protocol, we implemented our signature-based witness encryption scheme and evaluated it on a standard laptop with Intel i7 @2,3 GHz. For the popular BLS12-381 curve, a 381-bit message and a committee of size 500 the encryption time is 9.8s and decryption is 14.8s. The scheme remains practical for a committee of size 2000 with an encryption time of 58s and decryption time of 218s.


Primary Research Area

  • Algorithmic Foundations and Cryptography


@misc{Döttling:Hanzlik:Magri:Wohnig:2022, title = "McFly: Verifiable Encryption to the Future Made Practical.", author = "Döttling, Nico" AND "Hanzlik, Lucjan" AND "Magri, Bernardo" AND "Wohnig, Stella", year = 2022, month = 4 }

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