Crypto Seminar Talk with Ignacio Cascudo
Oplysninger om arrangementet
Tidspunkt
Sted
Nygaard-295, Finlandsgade 21-23, 8200 Aarhus N
Title: Verifiable Secret Sharing from Symmetric Key Cryptography with Improved Optimistic Complexity
Abstract: We propose verifiable secret sharing (VSS) schemes secure for any honest majority in the synchronous model, and that only use symmetric-key cryptographic tools (in fact, only random oracles), therefore having plausibly post-quantum security. Compared to the state-of-the-art scheme with these features, our main improvement lies on the complexity of the “optimistic” scenario where the dealer and all but a small number of receivers behave honestly in the sharing phase.
This VSS protocol is of interest in multiparty computations where each party runs one VSS as a dealer, such as distributed key generation protocols. Our main technical handle is a distributed zero-knowledge proof of "low degreeness" of a polynomial where the statement is distributed among several verifiers, each knowing one evaluation. Using folding techniques similar to FRI we construct such a proof where each verifier receives polylogarithmic information and runs in polylogarithmic time.
This talk is based on joint work with Daniele Cozzo and Emanuele Giunta, published in Asiacrypt 24.
About the Speaker: Ignacio Cascudo is an Associate Research Professor at IMDEA Software Institute in Madrid, Spain.