Publications

On Quarkslab’s Blog 💻 #

All of my articles are here.

Triple Threat: Signal’s Ratchet Goes Post-Quantum: A mid-level overview of Signal’s SPQR protocol, which brings post-quantum cryptography to the key derivation for messages.
Non-Compliant, So What?: A discussion on crypto findings in audits, specifically on (non-)compliance.
Secure Messaging Apps And Group Protocols part 1 and 2: A step-by-step explaination of how secure messaging is built. The second part focuses on group protocols, especially MLS.

Belenios, The Certification Campaign at SSTIC ‘24 (FR): This talk presents our work on the security evalutation of the Belenios voting solution as a Certification de Sécurité de Premier Niveau, the French simple alternative to Common Criteria. Link to the article. (EN)
Vulnérabilités cryptographiques : pourquoi sont-elles si méchantes ? at QITS ‘24 (FR): A talk on the kinds of vulnerabilities we have found during our audits/consulting missions, and how to avoid them. with Dahmun Goudarzi
Messaging Layer Security : plus on est de fous, plus on chiffre at QITS ‘23 (FR): A presentation of the MLS protocol, for group messaging.
Mattermost End-to-End Encryption plugin at Pass The Salt ‘22: A presentation of Quarkslab’s E2EE plugin for Mattermost, developed in 2021. with Adrien Guinet

SSE and SSD: Page-Efficient Searchable Symmetric Encryption at CRYPTO ‘21: with Raphael Bost, Pierre-Alain Fouque, Brice Minaud, and Michael Reichle; A study of page-efficiency for Searchable Symmetric Encryption on Solid State Drives.
Unlinkable and Invisible γ-Sanitizable Signatures at ACNS ‘21: with Xavier Bultet; An evolution of sanitizable signatures to add a limit to the number of possible modifications made.
Designing Reverse Firewalls for the Real World ESORICS ‘20: with Xavier Bultel, Pierre-Alain Fouque, Cristina Onete, and Thyla van der Merwe; We design a new model for reverse firewalls, which “sanitize” the client-side of a protocol to prevent exfiltration of information.
SAID: Reshaping Signal into an Identity-Based Asynchronous Messaging Protocol with Authenticated Ratcheting EuroS&P ‘19: with Olivier Blazy, Xavier Bultel, Pierre-Alain Fouque, Cristina Onete, and Elena Pagnin; A variant of Signal which is identity-based, instead of using a centralized server.

Provable security of real world protocols: Provable security is a very useful cryptographic tool that helps in the evaluation of the security of a protocol. In order to construct a proof, one must first define the security properties that are to be achieved, i.e., the security model, as well as what kind of adversary we are facing. In this thesis, we introduce (or adapt) models in which we give security proofs for three kinds of protocols with real-life applications: a secure messaging protocol, a sanitizable signature, and a reverse firewall.