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Inicio > Eventos > Charlas Invitadas > 2022 > Continuously Non-Malleable Secret Sharing in the Plain Model
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Antonio Faonio

martes 5 de abril de 2022

11:00am Zoom3 - (pass: 5551337)

Antonio Faonio, Assistant Professor, EURECOM, France

Continuously Non-Malleable Secret Sharing in the Plain Model


In this talk I will present a paper published at TCC'21 together with Gianluca Brian and Daniele Venturi from Sapienza University of Rome. We study non-malleable secret sharing against joint leakage and joint tampering attacks. Our main result is the first threshold secret sharing scheme in the plain model achieving resilience to noisy-leakage and continuous tampering. The above holds under (necessary) minimal computational assumptions (i.e., the existence of one-to-one one-way functions), and in a model where the adversary commits to a fixed partition of all the shares into non-overlapping subsets of at most t−1 shares (where t is the reconstruction threshold), and subsequently jointly leaks from and tampers with the shares within each partition. We study the capacity (i.e., the maximum achievable asymptotic information rate) of continuously non-malleable secret sharing against joint continuous tampering attacks. In particular, we prove that whenever the attacker can tamper jointly with k>t/2 shares, the capacity is at most t−k. The rate of our construction matches this upper bound. An important corollary of our results is the first non-malleable secret sharing scheme against independent tampering attacks breaking the rate-one barrier (under the same computational assumptions as above).