Secure Keyless Multi-Party Storage Scheme

Pascal Lafourcade (1) , Lola-Baie Mallordy (1) , Charles Olivier-Anclin (1, 2) , Léo Robert (3, 4)

1 LIMOS - Laboratoire d'Informatique, de Modélisation et d'Optimisation des Systèmes
2 be ys Pay
3 UPJV - Université de Picardie Jules Verne
4 MIS - Modélisation, Information et Systèmes - UR UPJV 4290

Using threshold secret sharing, we propose a solution tai-lored for forgetful clients (i.e., not required to keep any cryptographicsecret) while accommodating the dynamic nature of multi-cloud deploy-ments. Furthermore, we delegate the computation and distribution ofshares to an intermediate server (proxy), effectively minimizing the clientworkload. We propose two variants of a keyless, space-efficient multi-cloud storage scheme named KAPRE and KAME. Our solution KAPRErequires less communications and computations, while KAME preservesdata confidentiality against a colluding proxy. Our protocols offer robustguarantees for data integrity, and we demonstrate the proxy’s ability toidentify and attribute blame to servers responsible for sending corruptedshares during data reconstruction. We establish a comprehensive secu-rity model and provide proofs of the security properties of our protocols.To complement this theoretical analysis, we present a proof-of-conceptto illustrate the practical implementation of our proposed scheme.

Mots clés: Multi-cloud; secret sharing; homomorphic encryption

Domaines: Cryptographie et sécurité [cs.CR]

Pascal Lafourcade, Lola-Baie Mallordy, Charles Olivier-Anclin, Léo Robert. Secure Keyless Multi-Party Storage Scheme. ESORICS, Sep 2024, Bydgoszcz, Poland. ⟨hal-04540895⟩