1,783 research outputs found
Authentication enhancement in command and control networks: (a study in Vehicular Ad-Hoc Networks)
Intelligent transportation systems contribute to improved traffic safety by facilitating real time communication between vehicles. By using wireless channels for communication, vehicular networks are susceptible to a wide range of attacks, such as impersonation, modification, and replay. In this context, securing data exchange between intercommunicating terminals, e.g., vehicle-to-everything (V2X) communication, constitutes a technological challenge that needs to be addressed. Hence, message authentication is crucial to safeguard vehicular ad-hoc networks (VANETs) from malicious attacks. The current state-of-the-art for authentication in VANETs relies on conventional cryptographic primitives, introducing significant computation and communication overheads. In this challenging scenario, physical (PHY)-layer authentication has gained popularity, which involves leveraging the inherent characteristics of wireless channels and the hardware imperfections to discriminate between wireless devices. However, PHY-layerbased authentication cannot be an alternative to crypto-based methods as the initial legitimacy detection must be conducted using cryptographic methods to extract the communicating terminal secret features. Nevertheless, it can be a promising complementary solution for the reauthentication problem in VANETs, introducing what is known as “cross-layer authentication.” This thesis focuses on designing efficient cross-layer authentication schemes for VANETs, reducing the communication and computation overheads associated with transmitting and verifying a crypto-based signature for each transmission. The following provides an overview of the proposed methodologies employed in various contributions presented in this thesis.
1. The first cross-layer authentication scheme: A four-step process represents this approach: initial crypto-based authentication, shared key extraction, re-authentication via a PHY challenge-response algorithm, and adaptive adjustments based on channel conditions. Simulation results validate its efficacy, especially in low signal-to-noise ratio (SNR) scenarios while proving its resilience against active and passive attacks.
2. The second cross-layer authentication scheme: Leveraging the spatially and temporally correlated wireless channel features, this scheme extracts high entropy shared keys that can be used to create dynamic PHY-layer signatures for authentication. A 3-Dimensional (3D) scattering Doppler emulator is designed to investigate the scheme’s performance at different speeds of a moving vehicle and SNRs. Theoretical and hardware implementation analyses prove the scheme’s capability to support high detection probability for an acceptable false alarm value ≤ 0.1 at SNR ≥ 0 dB and speed ≤ 45 m/s.
3. The third proposal: Reconfigurable intelligent surfaces (RIS) integration for improved authentication: Focusing on enhancing PHY-layer re-authentication, this proposal explores integrating RIS technology to improve SNR directed at designated vehicles. Theoretical analysis and practical implementation of the proposed scheme are conducted using a 1-bit RIS, consisting of 64 × 64 reflective units. Experimental results show a significant improvement in the Pd, increasing from 0.82 to 0.96 at SNR = − 6 dB for multicarrier communications.
4. The fourth proposal: RIS-enhanced vehicular communication security: Tailored for challenging SNR in non-line-of-sight (NLoS) scenarios, this proposal optimises key extraction and defends against denial-of-service (DoS) attacks through selective signal strengthening. Hardware implementation studies prove its effectiveness, showcasing improved key extraction performance and resilience against potential threats.
5. The fifth cross-layer authentication scheme: Integrating PKI-based initial legitimacy detection and blockchain-based reconciliation techniques, this scheme ensures secure data exchange. Rigorous security analyses and performance evaluations using network simulators and computation metrics showcase its effectiveness, ensuring its resistance against common attacks and time efficiency in message verification.
6. The final proposal: Group key distribution: Employing smart contract-based blockchain technology alongside PKI-based authentication, this proposal distributes group session keys securely. Its lightweight symmetric key cryptography-based method maintains privacy in VANETs, validated via Ethereum’s main network (MainNet) and comprehensive computation and communication evaluations.
The analysis shows that the proposed methods yield a noteworthy reduction, approximately ranging from 70% to 99%, in both computation and communication overheads, as compared to the conventional approaches. This reduction pertains to the verification and transmission of 1000 messages in total
Multidisciplinary perspectives on Artificial Intelligence and the law
This open access book presents an interdisciplinary, multi-authored, edited collection of chapters on Artificial Intelligence (‘AI’) and the Law. AI technology has come to play a central role in the modern data economy. Through a combination of increased computing power, the growing availability of data and the advancement of algorithms, AI has now become an umbrella term for some of the most transformational technological breakthroughs of this age. The importance of AI stems from both the opportunities that it offers and the challenges that it entails. While AI applications hold the promise of economic growth and efficiency gains, they also create significant risks and uncertainty. The potential and perils of AI have thus come to dominate modern discussions of technology and ethics – and although AI was initially allowed to largely develop without guidelines or rules, few would deny that the law is set to play a fundamental role in shaping the future of AI. As the debate over AI is far from over, the need for rigorous analysis has never been greater. This book thus brings together contributors from different fields and backgrounds to explore how the law might provide answers to some of the most pressing questions raised by AI. An outcome of the Católica Research Centre for the Future of Law and its interdisciplinary working group on Law and Artificial Intelligence, it includes contributions by leading scholars in the fields of technology, ethics and the law.info:eu-repo/semantics/publishedVersio
LIPIcs, Volume 251, ITCS 2023, Complete Volume
LIPIcs, Volume 251, ITCS 2023, Complete Volum
Automated Formation Control Synthesis from Temporal Logic Specifications
In this paper, we propose a novel framework using formal methods to
synthesize a navigation control strategy for a multi-robot swarm system with
automated formation. The main objective of the problem is to navigate the robot
swarm toward a goal position while passing a series of waypoints. The formation
of the robot swarm should be changed according to the terrain restrictions
around the corresponding waypoint. Also, the motion of the robots should always
satisfy certain runtime safety requirements, such as avoiding collision with
other robots and obstacles. We prescribe the desired waypoints and formation
for the robot swarm using a temporal logic (TL) specification. Then, we
formulate the transition of the waypoints and the formation as a deterministic
finite transition system (DFTS) and synthesize a control strategy subject to
the TL specification. Meanwhile, the runtime safety requirements are encoded
using control barrier functions, and fixed-time control Lyapunov functions
ensure fixed-time convergence. A quadratic program (QP) problem is solved to
refine the DFTS control strategy to generate the control inputs for the robots,
such that both TL specifications and runtime safety requirements are satisfied
simultaneously. This work enlights a novel solution for multi-robot systems
with complicated task specifications. The efficacy of the proposed framework is
validated with a simulation study
Barrier-Based Test Synthesis for Safety-Critical Systems Subject to Timed Reach-Avoid Specifications
We propose an adversarial, time-varying test-synthesis procedure for
safety-critical systems without requiring specific knowledge of the underlying
controller steering the system. From a broader test and evaluation context,
determination of difficult tests of system behavior is important as these tests
would elucidate problematic system phenomena before these mistakes can engender
problematic outcomes, e.g. loss of human life in autonomous cars, costly
failures for airplane systems, etc. Our approach builds on existing,
simulation-based work in the test and evaluation literature by offering a
controller-agnostic test-synthesis procedure that provides a series of
benchmark tests with which to determine controller reliability. To achieve
this, our approach codifies the system objective as a timed reach-avoid
specification. Then, by coupling control barrier functions with this class of
specifications, we construct an instantaneous difficulty metric whose minimizer
corresponds to the most difficult test at that system state. We use this
instantaneous difficulty metric in a game-theoretic fashion, to produce an
adversarial, time-varying test-synthesis procedure that does not require
specific knowledge of the system's controller, but can still provably identify
realizable and maximally difficult tests of system behavior. Finally, we
develop this test-synthesis procedure for both continuous and discrete-time
systems and showcase our test-synthesis procedure on simulated and hardware
examples
Evaluating Architectural Safeguards for Uncertain AI Black-Box Components
Although tremendous progress has been made in Artificial Intelligence (AI), it entails new challenges. The growing complexity of learning tasks requires more complex AI components, which increasingly exhibit unreliable behaviour. In this book, we present a model-driven approach to model architectural safeguards for AI components and analyse their effect on the overall system reliability
Conservative Safety Monitors of Stochastic Dynamical Systems
Generating accurate runtime safety estimates for autonomous systems is vital
to ensuring their continued proliferation. However, exhaustive reasoning about
future behaviors is generally too complex to do at runtime. To provide scalable
and formal safety estimates, we propose a method for leveraging design-time
model checking results at runtime. Specifically, we model the system as a
probabilistic automaton (PA) and compute bounded-time reachability
probabilities over the states of the PA at design time. At runtime, we combine
distributions of state estimates with the model checking results to produce a
bounded time safety estimate. We argue that our approach produces
well-calibrated safety probabilities, assuming the estimated state
distributions are well-calibrated. We evaluate our approach on simulated water
tanks
"Le present est plein de l’avenir, et chargé du passé" : Vorträge des XI. Internationalen Leibniz-Kongresses, 31. Juli – 4. August 2023, Leibniz Universität Hannover, Deutschland. Band 3
[No abstract available]Deutschen Forschungsgemeinschaft (DFG)/Projektnr. 517991912VGH VersicherungNiedersächsisches Ministerium für Wissenschaft und Kultur (MWK
Continuous-time control synthesis under nested signal temporal logic specifications
Signal temporal logic (STL) has gained popularity in robotics for expressing
complex specifications that may involve timing requirements or deadlines. While
the control synthesis for STL specifications without nested temporal operators
has been studied in the literature, the case of nested temporal operators is
substantially more challenging and requires new theoretical advancements. In
this work, we propose an efficient continuous-time control synthesis framework
for nonlinear systems under nested STL specifications. The framework is based
on the notions of signal temporal logic tree (sTLT) and control barrier
function (CBF). In particular, we detail the construction of an sTLT from a
given STL formula and a continuous-time dynamical system, the sTLT semantics
(i.e., satisfaction condition), and the equivalence or under-approximation
relation between sTLT and STL. Leveraging the fact that the satisfaction
condition of an sTLT is essentially keeping the state within certain sets
during certain time intervals, it provides explicit guidelines for the CBF
design. The resulting controller is obtained through the utilization of an
online CBF-based program coupled with an event-triggered scheme for online
updating the activation time interval of each CBF, with which the correctness
of the system behavior can be established by construction. We demonstrate the
efficacy of the proposed method for single-integrator and unicycle models under
nested STL formulas.Comment: Link to accompanying code: https://github.com/xiaotanKTH/sTL
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