Précédents séminaires

17/12/2024  •  Pairing-Free Blind Signatures from Standard Assumptions in the ROM

Ky NGUYEN, Doctorant (ENS)

Blind Signatures are a useful primitive for privacy preserving applications such as electronic payments, e-voting, anonymous credentials, and more. However, existing practical blind signature schemes based on standard assumptions require either pairings or lattices. We present the first practical construction of a round-optimal blind signature in the random oracle model based on standard assumptions without resorting to pairings or lattices. In particular, our construction is secure under...

19/11/2024  •  Shaken, not Stirred - Automated Discovery of Subtle Attacks on Protocols using Mix-Nets

Dhekra MAHMOUD, Doctorante

Mix-Nets are used to provide anonymity by passing a list of inputs through a collection of mix servers. Each server mixes the entries to create a new anonymized list, so that the correspondence between the output and the input is hidden. These Mix-Nets are used in numerous protocols in which the anonymity of participants is required, for example voting or electronic exam protocols. Some of these protocols have been proven secure using automated tools such as the cryptographic protocol...

15/10/2024  •  Anonymity Model and Design of Different Signature Types

Charles OLIVIER-ANCLIN, Doctorant

Security models provide a way of formalising security properties in a rigorous way, but it is sometimes difficult to ensure that the model really fits the concept that we are trying to formalise. In this paper, we illustrate this fact by showing the discrepancies between the security model of anonymity in linkable ring signatures and the security that is actually expected for this kind of signature. These signatures allow a user to sign anonymously within an ad hoc group generated from...

18/06/2024  •  Design of Secure Multi-Users Protocols: Applications to Bandits, Ticketing and File Transfer

Gaël MARCADET, Doctorant

Répétition de soutenance de thèse

Cryptographic protocols establish a series of interactions among numerous users to deliver specific functionality while ensuring various properties, a protocol being considered secure when it successfully ensures all intended properties. Accomplishing these properties requires the utilisation of cryptographic primitives, whose usage may entail computation overhead and hence limiting the scalability of the protocol. Throughout this...

21/05/2024  •  Convergence sûreté-sécurité des systèmes de contrôle industriels

Mike DA SILVA, Doctorant (CEA LETI)

Les systèmes industriels sont à l'origine de la production de bien en transformant et en utilisant des matières premières. Ces systèmes répondent à nos besoins quotidiens comme en énergie électrique fournie par les centrales électriques, ou encore en nourriture fournie par l'industrie agroalimentaire. Un système industriel, quel qu'il soit, interagit toujours avec un procédé physique qu'il doit contrôler pour produire le bien attendu (nourriture, énergie, etc.). Ce contrôle se fait...