Authenticated Timing Protocol Based on Galileo ACAS

arXiv (Cornell University), 2023

Global navigation satellite systems (GNSSs) are implementing security mechanisms: examples are Galileo open service navigation message authentication (OS-NMA) and GPS chips-message robust authentication (CHIMERA). Each of these mechanisms operates in a single band. However, nowadays, even commercial GNSS receivers typically compute the position, velocity, and time (PVT) solution using multiple constellations and signals from multiple bands at once, significantly improving both accuracy and availability. Hence, cross-authentication checks have been proposed, based on the PVT obtained from the mixture of authenticated and non-authenticated signals. In this paper, first, we formalize the models for the crossauthentication checks. Next, we describe, for each check, a spoofing attack to generate a fake signal leading the victim to a target PVT without notice. We analytically relate the degrees of the freedom of the attacker in manipulating the victim's solution to both the employed security checks and the number of open signals that can be tampered with by the attacker. We test the performance of the considered attack strategies on an experimental dataset. Lastly, we show the limits of the PVT-based GNSS cross-authentication checks, where both authenticated and non-authenticated signals are used.

2018 26th European Signal Processing Conference (EUSIPCO), 2018

Global navigation satellite systems (GNSS) are widely used in many civil applications to get information on position, velocity and timing (PVT). However, current systems (such as global positioning system (GPS) and Galileo) do not include any feature to authenticate the received signal, therefore leaving open the possibility from an attacker to spoof the GNSS signal and induce a wrong PVT computation at the receiver. In this paper we propose a solution based on the superposition of an authentication message (signature) and artificial noise (AN) on top of the existing navigation signal. Both the authentication message and AN are unpredictable and therefore can not be arbitrarily generated by an attacker. After transmission, through an external public authenticated but asynchronous (thus not useful for PVT) channel, both the authentication message and the AN are revealed, allowing the receiver to check if they were present along the previously received navigation signal. We consider the hypothesis testing problem at the legitimate receiver to decide the authenticity of the message, and we analyze its performance under two attacks: a generation attack in which the attacker does not generate the authentication signal and a replay attack in which a legitimate (including authentication message) signal is replayed by the attacker with a suitable delay in order to induce the desired PVT at the victim. The receiver operating characteristic (ROC) curve is obtained for the hypothesis testing problem under the two attacks.

2018 Global Internet of Things Summit (GIoTS), 2018

Time synchronization is fundamental for a wide variety of IoT applications. Time is also fundamental to provide security services such as certificates or OAuth-token validation. Having a secure source of time is a fundamental problem, and the first step to provide other services for applications. There is no standardized lightweight and secure time synchronization solution suitable for IoT. We propose a Lightweight Authenticated Time (LATe) Synchronization Protocol. Our proposal is based on IETF open standards and is agnostic to underlying communication technologies. We also provide a computer-aided proof of the security claims using the Scyther tool.

2015

Currently, the operational Global Navigation Satellite Systems (GNSS) do not offer message, nor signal Authentication and Integrity Protection toward the Open Service (OS) users. But a well-motivated attacker equipped with a single antenna can successively perform several attacks, e.g. Jamming, and Signal-Synthesis attack to affect the position solution, or even a Replay attack which modify the timing awareness. Because of this threats, robust defending techniques are needed. The nascent European navigation system-Galileo, aspires to offer an E1 OS signal authentication and integrity protection mechanism integrated from the outset. Actually, a wide State-Of-Art about defende techniques already exists. But these all have a common vulnerability: they are based on computationally secure algorithms (e.g. Digital Signal Algorithm), or are designed only against a specific attack. This thesis work, inserted into a collaborative project with the European Space Agency (ESA), aims at contributing to the issue by adopting a different approach. Namely, we deal the problem from the Physical Layer point of view, and without limiting the attacker capabilities and advantages. Furthermore, no specific authentication scheme is chosen or designed, but only generic channel models are considered. In this manner, a theoretic key entropy lower bound is defined for both Data and Signal level. Their performance is then presented considering some simplified channel and signal setting, but against a well-equipped attacker. In addition, the Data-layer bound is compared with the actual most promising protocol-TESLA. Therefore, the work provides a reference bound to guarantee unconditionally secure Authentication and Integrity Protection. Finally, the DLR channel model is exploited in order to extract some useful features (e.g. coherence time) within a more realistic scenery.

2017

This paper proposes a set of Key Performance Indicators (KPIs) for European GNSS (EGNSS)-based timing services that are relevant from the user perspective; these KPIs quantify the accuracy, integrity, and stability of the services. Furthermore, the instrumentation and procedures required for reproducing the threats and evaluating the proposed KPIs are described. The proposed test setup makes use of a precise time/frequency reference distributing a Coordinated Universal Time (UTC) realization and is intended for post-processing. The test results provide an indication of the performance of the envisioned Galileo and EGNOS timing services in terms of the proposed KPIs when the receiver is subject to various abnormal

Journal of Global Positioning Systems, 2004

This paper describes a secure framework for tracking applications that use the Galileo signal authentication services. First a number of limitations that affect the trust of critical tracking applications, even in presence of authenticated GNSS signals, are detailed. Requirements for secure tracking are then introduced; detailing how the integrity characteristics of the Galileo authentication could enhance the security of active tracking applications. This paper concludes with a discussion of our existing tracking technology using a Siemens TC45 GSM/GPRS module and future development utilizing our previously proposed trusted GNSS receiver.

Proceedings of the IEEE, 2016

2019 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control, and Communication (ISPCS), 2019

The lack of integrated support for security has been a major shortcoming of Precision Time Protocol version 2 (PTPv2) for a long time. The upcoming PTPv2.1 aims at addressing this shortcoming in a variety of ways, including the introduction of lightweight message authentication. In this paper we provide an overview of the planned security features, and report results based on an implementation of the proposed integrated security mechanism based on the open source Linux PTP, including support for hardware timestamping. Our implementation includes an extension of Linux PTP to support transparent clocks. We provide results from an experimental testbed including a transparent clock, which illustrate that the extensions can be implemented in software at a low computational overhead, while supporting hardware timestamping. We also provide a discussion of the remaining vulnerabilities of PTP time synchronization, propose countermeasures, and discuss options for key management, which is not covered by the standard.

2016

In the proposals for Global Navigation Satellite Systems (GNSS) Navigation Message Authentication (NMA) that are based on adapting the Timed Efficient Stream Loss-Tolerant Authentication (TESLA) protocol, the length of the one-time keys is limited (e.g. to 80 bits) by the low transmission rate. As a consequence, the hash function that is used to build the one-way key chain is constructed having a longer, secure hash function (e.g. SHA-256), preceded by a time-varying yet deterministic padding of the input and followed by a truncation of the output. We evaluate the impact of this construction on the collision resistance of the resulting hash function and of the whole chain, and show that with current proposed parameters, combined with the use of efficient hashing hardware, it can lead to a feasible attack with significant collision probability. The collision can be leveraged to mount a long lasting spoofing attack, where the victim receiver accepts all the one time keys and the navigation messages transmitted by the attacker as authentic. We conclude by suggesting possible modifications to make TESLA-based NMA more robust to such attacks.