Description
Users increasingly rely on the ``social cloud'' for storing and sharing personal information, for establishing new contacts, and for interacting with their friends and colleagues. Even though social media platforms may differ in the target audience, in the nature of collected and disseminated information, and in services offered to the users, there are several building blocks that enable user's social interactions and are deployed by the majority of these platforms. Designing these building blocks in a secure and privacy-preserving way is of utmost importance, should potential damage from the misuse of user-provided content in the existing ``social cloud'' be averted.<br/> Due to the absence of appropriate models and security/privacy definitions it is, so far, impossible to judge, whether a proposed protection mechanism is suitable or not, whether it can be applied in general, or is tailored to a specific social media platform. Instead of using ``ad-hoc'' and ``best practice'' solutions with questionable guarantees, it is advisable to strive for a more formal treatment of the underlying building blocks by providing sophisticated security/privacy definitions and designing solutions amenable to formal reasoning and security proofs.<br/> In the first part of my talk I will focus on the management of personal user profiles. User profiles serve as a main building block for most social media platforms. I will introduce a formal cryptographic model for \emph{private} user profiles, supporting generation of the digital content owned by the user and its controlled disclosure to other users of the social community. I will present formal definitions of security and privacy that reflect the natural expectations on private profiles. I will further describe two general solutions based on different encryption techniques and highlight their trade-offs from the security/privacy and complexity point of view. These solutions do not require any specific network infrastructure or any trusted third parties. The provided analysis takes into account statistics of several real-world social media platforms. The second part of my talk will address the problem of discovery of common social contacts, for which I will introduce the first privacy-friendly practical solution that lets two users, on input their respective contact lists, learn their common contacts (if any), and nothing else. The proposed protocol prevents arbitrary list manipulation by means of contact certification, and guarantees user authentication and revocability. I will explain why current approaches such as private set intersection or anonymous credentials, although being related, do not provide an appropriate solution to this problem. I will discuss the modeling of contact-hiding security that private contact discovery should provide. I will also highlight efficiency considerations for the proposed protocol that does not require involvement of any trusted third parties and can be deployed in resource-constraint environments.<br/> The content of this talk is based on the recent results from FC 2011/RLCSP, ASIACCS 2011, and ACNS 2011.
Prochains exposés
-
La crypto-graphie et les crypto-monnaies
Orateur : Daniel Augot - INRIA Saclay—Île-de-France
De nos jours, la requête «crypto» dans un moteur de recherche renvoieaux cryptomonnaies. Mais «crypto means crypto», et on peut se poser laquestion des liens pertinents entre les deux domaines. D'un coté, le monde des cryptomonnaies et de la technologiesous-jacente s'est développé et évolue encore en dehors du mondeacadémique. Il faut suivre d'un coté des posts de blog, des fils dediscussion X[…] -
SoK: Security of the Ascon Modes
Orateur : Charlotte Lefevre - Radboud University
The Ascon authenticated encryption scheme and hash function of Dobraunig et al (Journal of Cryptology 2021) were recently selected as winner of the NIST lightweight cryptography competition. The mode underlying Ascon authenticated encryption (Ascon-AE) resembles ideas of SpongeWrap, but not quite, and various works have investigated the generic security of Ascon-AE, all covering different attack[…] -
Comprehensive Modelling of Power Noise via Gaussian Processes with Applications to True Random Number Generators
Orateur : Maciej Skorski - Laboratoire Hubert Curien
The talk examines power noise modelling through Gaussian Processes for secure True Random Number Generators. While revisiting one-sided fractional Brownian motion, we obtain novel contributions by quantifying posterior uncertainty in exact analytical form, establishing quasi-stationary properties, and developing rigorous time-frequency analysis. These results are applied to model oscillator[…]-
Cryptography
-
TRNG
-
-
CryptoVerif: a computationally-sound security protocol verifier
Orateur : Bruno Blanchet - Inria
CryptoVerif is a security protocol verifier sound in the computational model of cryptography. It produces proofs by sequences of games, like those done manually by cryptographers. It has an automatic proof strategy and can also be guided by the user. It provides a generic method for specifying security assumptions on many cryptographic primitives, and can prove secrecy, authentication, and[…]-
Cryptography
-