Math Junior Seminar

Mercoledì 25 febbraio alle ore 14:00, nell'ambito dei Junior Seminars dei dottorandi di Matematica, Sara Giammusso (Sapienza) terrà il seminario dal titolo "Taming Adaptive Security and New Access Structures in Evolving Secret Sharing".

Abstract: Secret sharing is a fundamental cryptographic primitive that allows a secret to be distributed among multiple parties so that only authorized subsets can reconstruct it. Traditional secret sharing schemes assume that the set of participants and the access policy are fixed in advance. However, in many real-world scenarios—such as dynamic networks or long-lived systems—participants may join over time, and the access structure may not be known beforehand.
Evolving secret sharing, introduced by Komargodski, Naor, and Yogev, addresses this challenge by allowing a dealer to distribute shares online, without knowing the total number of participants or the final access structure in advance, and without ever modifying previously distributed shares. In this seminar, we study evolving secret sharing in the computational setting, where security is required only against computationally bounded adversaries.
We present new constructions of evolving secret sharing schemes for rich classes of access structures, including dynamic weighted threshold policies and all evolving monotone functions in NP. Furthermore, we initiate the study of adaptive security in this setting, where an adversary can choose which participants to corrupt as the system evolves. We show how to achieve adaptive security for dynamic weighted thresholds and for evolving monotone circuits.
Overall, this work significantly expands the scope of evolving secret sharing and provides new tools for building secure systems in dynamic and unpredictable environments.

Il seminario organizzato dai dottorandi di Matematica e si svolgerà in presenza presso il Dipartimento di Matematica e Fisica, via della Vasca Navale 84, aula B.

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