csstalk

Computer-Aided Formal Security Analysis of the Web Platform

In this talk, Matteo Maffei will give an overview on this research line, illustrating how formal methods can positively impact browser and web security. He will initially exemplify how web security properties can be formalized and enforced, both in browsers and at the level of web specifications. He will then focus on WebSpec, a framework encompassing a formal model of the browser in Coq and a compiler turning Coq specifications into SMT-Lib formulas, thereby enabling the usage of off-the-shelf SMT solvers to automatically discover vulnerabilities and prove security properties. This line of research brings together formal methods and applied security in a cross-fertilizing feedback loop: vulnerabilities identified in the model are measured in the wild and large-scale evaluations often bring back new threat models that are then fed into the formal specification. This approach allowed us to identify a number of vulnerabilities in the specification and interaction of web components, and to identify fixes that we proved correct in our model.

Mind the gap: the challenges of taking differential privacy out of the lab and into the field

Differential privacy is a formal model of privacy protection that has received sustained attention from the research community, whose work has shown that it is possible to reveal accurate information about a population while rigorously protecting the privacy of its constituents. While DP offers a compelling promise, organizations that choose to adopt it as their privacy standard face a number of challenges doing so.

How have threat models changed since 2018 and how hardware security can help handle the new threats?

Since the disclosure of Spectre attacks in 2018, both academia and industry have made considerable efforts to defend against all variants of transient execution attacks, the class of attacks to which Spectre belongs to. The first part of this presentation will be dedicated to discovering how these attacks change the way we reason about threat models in security. The second part of the presentation will introduce a new generic formal processor model - called ProSpeCT - to prevent transient execution attacks by construction. ProSpeCT has also been implemented on top of an open-source RISC-V processor and will be presented in Usenix Security 23 in a joint work with Lesly-Ann Daniel, Marton Bognar, Job Noorman, Sébastien Bardin, and Frank Piessens.

Categorical Composable Cryptography

We formalize the simulation paradigm of cryptography in terms of category theory and show that protocols secure against abstract attacks form a symmetric monoidal category (≈ can be composed sequentially and in parallel). This gives an abstract model of composable security definitions in cryptography that is not tied to any particular machine model. Our model is able to incorporate computational security, set-up assumptions and various attack models such as colluding or independently acting subsets of adversaries in a modular, flexible fashion. We conclude by using string diagrams to rederive the security of the one-time pad and no-go results concerning the limits of bipartite and tripartite cryptography, ruling out e.g., composable commitments and broadcasting.

Composable Non-interactive Zero-knowledge Proofs in the Random Oracle Model

In this talk, I will give an overview of techniques to compile Sigma protocols—a popular class of interactive cryptographic proofs—to non-interactive proofs that guarantee security when used in any larger protocol context. The aim of the talk will be to provide an introduction to the area to system designers who typically use cryptographic tools as a black box, while also providing insight into some interesting technical subtleties that I uncovered in a recent work.

FrodoPIR: Simple, Scalable, Single-Server Private Information Retrieval

In this talk, Sofía will present FrodoPIR, a highly configurable, stateful, singleserver Private Information Retrieval (PIR) scheme that involves an offline phase that is completely client-independent.

Privacy with Good Taste: A Case Study in Quantifying Privacy Risks in Genetic Scores

In this talk, Raul will present a novel methodology to quantify and prevent privacy risks by focusing on polygenic scores and phenotypic information.

Publicly Auditable Privacy Revocation

This seminar presents research on anonymous credentials with Publicly Auditable Privacy Revocation (PAPR). PAPR credentials simultaneously provide conditional user privacy and auditable privacy revocation for credential systems.

PrePaMS: Privacy-Preserving Participant Management for Studies with Rewards

Felix will introduce PrePaMS, an efficient participation management system that supports prerequisite checks and reward procedures in a privacy-preserving way. By using a set of proven cryptographic primitives and mechanisms, participations are protected so that service providers and organizers cannot derive the identity of participants even within the reward process.

Social psychology and its potential effect on security when developing software systems

In this talk, Lucas will address the under-researched area of combining social psychology findings with the construction of secure software systems.