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Publications

Publications by Hugo Pereira Pacheco

2020

ROSY: An elegant language to teach the pure reactive nature of robot programming

Authors
Pacheco, H; Macedo, N;

Publication
2020 FOURTH IEEE INTERNATIONAL CONFERENCE ON ROBOTIC COMPUTING (IRC 2020)

Abstract
Robotics is very appealing and is long recognized as a great way to teach programming, while drawing inspiring connections to other branches of engineering and science such as maths, physics or electronics. Although this symbiotic relationship between robotics and programming is perceived as largely beneficial, educational approaches often feel the need to hide the underlying complexity of the robotic system, but as a result fail to transmit the reactive essence of robot programming to the roboticists and programmers of the future. This paper presents ROSY, a novel language for teaching novice programmers through robotics. Its functional style is both familiar with a high-school algebra background and a materialization of the inherent reactive nature of robotic programming. Working at a higher-level of abstraction also teaches valuable design principles of decomposition of robotics software into collections of interacting controllers. Despite its simplicity, ROSY is completely valid Haskell code compatible with the ROS ecosystem. We make a convincing case for our language by demonstrating how non-trivial applications can be expressed with ease and clarity, exposing its sound functional programming foundations, and developing a web-enabled robot programming environment.

2023

Formally verifying Kyber Episode IV: Implementation correctness

Authors
Almeida, JB; Barbosa, M; Barthe, G; Grégoire, B; Laporte, V; Léchenet, JC; Oliveira, T; Pacheco, H; Quaresma, M; Schwabe, P; Séré, A; Strub, PY;

Publication
IACR Trans. Cryptogr. Hardw. Embed. Syst.

Abstract
In this paper we present the first formally verified implementations of Kyber and, to the best of our knowledge, the first such implementations of any post-quantum cryptosystem. We give a (readable) formal specification of Kyber in the EasyCrypt proof assistant, which is syntactically very close to the pseudocode description of the scheme as given in the most recent version of the NIST submission. We present high-assurance open-source implementations of Kyber written in the Jasmin language, along with machine-checked proofs that they are functionally correct with respect to the EasyCrypt specification. We describe a number of improvements to the EasyCrypt and Jasmin frameworks that were needed for this implementation and verification effort, and we present detailed benchmarks of our implementations, showing that our code achieves performance close to existing hand-optimized implementations in C and assembly.

2021

Machine-checked ZKP for NP relations: Formally Verified Security Proofs and Implementations of MPC-in-the-Head

Authors
Bacelar Almeida, JC; Barbosa, M; Eldefrawy, K; Lengrand, SG; Pacheco, H; Pereira, V;

Publication
CCS '21: PROCEEDINGS OF THE 2021 ACM SIGSAC CONFERENCE ON COMPUTER AND COMMUNICATIONS SECURITY

Abstract
MPC-in-the-Head (MitH) is a general framework that enables constructing efficient zero-knowledge (ZK) protocols for NP relations from secure multiparty computation (MPC) protocols. In this paper we present the first machine-checked implementations of MitH. We begin with an EasyCrypt formalization that preserves the modular structure of the original construction and can be instantiated with arbitrary MPC protocols, and secret sharing and commitment schemes satisfying standard notions of security. We then formalize various suitable components, which we use to obtain full-fledged ZK protocols for general relations. We compare two approaches for obtaining verified executable implementations. The first uses a fully automated extraction from EasyCrypt to OCaml. The second reduces the trusted computing base (TCB) and provides better performance by combining code extraction with formally verified manual low-level components implemented in the Jasmin language. We conclude with a discussion of the trade-off between the formal verification effort and the performance of resulting executables, and how our approach opens the way for fully verified implementations of state-of the-art optimized protocols based on MitH.

2018

hnforcing ideal-world leakage bounds in real-world secret sharing MPC frameworks

Authors
Almeida, JB; Barbosa, M; Barthe, G; Pacheco, H; Pereira, V; Portela, B;

Publication
IEEE 31ST COMPUTER SECURITY FOUNDATIONS SYMPOSIUM (CSF 2018)

Abstract
We give a language-based security treatment of domain-specific languages and compilers for secure multi-party computation, a cryptographic paradigm that. enables collaborative computation over encrypted data. Computations are specified in a core imperative language, as if they were intended to be executed by a trusted-third party, and formally verified against. an information-flow policy modelling (an upper bound to) their leakage. This allows non-experts to assess the impact of performance driven authorized disclosure of intermediate values. Specifications are then compiled to multi-party protocols. We formalize protocol security using (distributed) probabilistic information-flow and prove security-preserving compilation: protocols only leak what. is allowed by the source policy. The proof exploits a natural but previously missing correspondence between simulation-based cryptographic proofs and (composable) probabilistic non-interference. Finally, we extend our framework to justify leakage cancelling, a domain-specific optimization that allows to first write an efficient specification that fails to meet the allowed leakage upper-bound, and then apply a probabilistic preprocessing that brings leakage to the acceptable range.

2025

Hyper model checking for high-level relational models

Authors
Macedo, N; Pacheco, H;

Publication
CoRR

Abstract

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