Gael MARCADET - Digital Security
Date: March 14th 2023 Location: Eurecom - Eurecom
Bio : Gael Marcadet, Université Clermont-Ferrand Biography After a bachelor degree in economics and a master degree in software development, I started a PhD in cybersecurity/cryptography, under the supervision of Pascal Lafourcade (Professor at LIMOS) and supervised by Marta Soare (Associate Professor at LIFO) and Radu Ciucanu (Associate Professor with accreditation to supervise research at LIFO). Now in my second year, my researches are focused on verifiable computation, a subject that has many applications in the private sector. Abstract : The verification of computations performed by an untrusted server is a cornerstone for delegated computations, especially in multi-clients setting where inputs are provided by different parties. Assuming a common secret between clients, a garbled circuit offers the attractive property to ensure the correctness of a result computed by the untrusted server while keeping the input and the function private. Yet, this verification can be guaranteed only once. Based on the notion of multi-key homomorphic encryption (MKHE), we propose RMC-PVC a multi-client verifiable computation protocol, able to verify the correctness of computations performed by an untrusted server for inputs (encoded for a garbled circuit) provided by multiple clients. Thanks to MKHE, the garbled circuit is reusable an arbitrary number of times. In addition, each client can verify the computation by its own. Compared to a single-key FHE scheme, the MKHE usage in RMC-PVC allows to reduce the workload of the server and thus the response delay for the client. It also enforce the privacy of inputs, which are provided by different clients.