54 research outputs found
Man-in-the-Middle Attack Resistant Secret Key Generation via Channel Randomization
Physical-layer based key generation schemes exploit the channel reciprocity
for secret key extraction, which can achieve information-theoretic secrecy
against eavesdroppers. Such methods, although practical, have been shown to be
vulnerable against man-in-the-middle (MitM) attacks, where an active adversary,
Mallory, can influence and infer part of the secret key generated between Alice
and Bob by injecting her own packet upon observing highly correlated
channel/RSS measurements from Alice and Bob. As all the channels remain stable
within the channel coherence time, Mallory's injected packets cause Alice and
Bob to measure similar RSS, which allows Mallory to successfully predict the
derived key bits. To defend against such a MitM attack, we propose to utilize a
reconfigurable antenna at one of the legitimate transceivers to proactively
randomize the channel state across different channel probing rounds. The
randomization of the antenna mode at every probing round breaks the temporal
correlation of the channels from the adversary to the legitimate devices, while
preserving the reciprocity of the channel between the latter. This prevents key
injection from the adversary without affecting Alice and Bob's ability to
measure common randomness. We theoretically analyze the security of the
protocol and conduct extensive simulations and real-world experiments to
evaluate its performance. Our results show that our approach eliminates the
advantage of an active MitM attack by driving down the probability of
successfully guessing bits of the secret key to a random guess.Comment: 13 pages, 8 figures, 4 table
Secret Key Generation Schemes for Physical Layer Security
Physical layer security (PLS) has evolved to be a pivotal technique in ensuring secure wireless communication. This paper presents a comprehensive analysis of the recent developments in physical layer secret key generation (PLSKG). The principle, procedure, techniques and performance metricesare investigated for PLSKG between a pair of users (PSKG) and for a group of users (GSKG). In this paper, a detailed comparison of the various parameters and techniques employed in different stages of key generation such as, channel probing, quantisation, encoding, information reconciliation (IR) and privacy amplification (PA) are provided. Apart from this, a comparison of bit disagreement rate, bit generation rate and approximate entropy is also presented. The work identifies PSKG and GSKG schemes which are practically realizable and also provides a discussion on the test bed employed for realising various PLSKG schemes. Moreover, a discussion on the research challenges in the area of PLSKG is also provided for future research
Design of an Efficient OFDMA-Based Multi-User Key Generation Protocol
Secret key generation exploits the unique random features of wireless channels, hence it is eminently suitable for the resource constrained Internet of Things applications. However, it has only been involved for single links between a pair of users, whilst there is a paucity of literature on group and multi-user key generation. This paper proposes an orthogonal frequency-division multiple access (OFDMA)-based multi-user key generation protocol to efficiently establish keys in a star topology. The uplink and downlink multi-user access facilitated by OFDMA allows the central node to simultaneously communicate with multiple users, which can significantly reduce the channel probing overhead. In particular, we provide a compelling case study of multi-user secret key generation by designing a prototype based on IEEE~802.11ax, a new Wi-Fi standard to be released. Our simulation results have demonstrated that the OFDMA-based multi-user key generation protocol incurs low interference amongst the users, whilst benefiting from channel reciprocity and generating unique random keys
Towards fast and robust authentication schemes in Body Area Networks
The emergence of Body Area Networks (BANs) has paved the way for real-time sensing
of human biometrics in addition to remote control of smart medical devices,
which in turn is beginning to revolutionise the smart healthcare industry. However,
due to their limited power and computational capabilities they are vulnerable to myriad
of security attacks, thus securing BANs is paramount to their success and wider
adoption in the medical and nonmedical domain. Achieving the desired security level
for BANs while adhering to their strict constraints imposed by the limited resources
available is an ongoing challenge. Solving such a challenge will be the focus of my
thesis. In particular, my thesis will develop a novel, fast and robust authentication
mechanisms amongst BAN devices while exploring new potential vulnerabilities that
may threaten the existing approaches. To accomplish this goal the thesis provides a
review of the state-of-the-art literature exploring authentication protocols that focus
on biometrics, physical channel characters or other approaches, before proceeding to
introduce three novel works. Firstly, identifying a concerning vulnerability within existing
Electrocardiogram (ECG) based schemes, secondly, a solution to mitigate this
exploit and finally a strategy which aims to reduce the time taken to complete the
authentication process
Towards Practical and Secure Channel Impulse Response-based Physical Layer Key Generation
Der derzeitige Trend hin zu âsmartenâ GerĂ€ten bringt eine Vielzahl an Internet-fĂ€higen und verbundenen GerĂ€ten mit sich. Die entsprechende Kommunikation dieser GerĂ€te muss zwangslĂ€uïŹg durch geeignete MaĂnahmen abgesichert werden, um die datenschutz- und sicherheitsrelevanten Anforderungen an die ĂŒbertragenen Informationen zu erfĂŒllen. Jedoch zeigt die Vielzahl an sicherheitskritischen VorfĂ€llen im Kontext von âsmartenâ GerĂ€ten und des Internets der Dinge auf, dass diese Absicherung der Kommunikation derzeit nur unzureichend umgesetzt wird.
Die Ursachen hierfĂŒr sind vielfĂ€ltig: so werden essentielle SicherheitsmaĂnahmen im Designprozess mitunter nicht berĂŒcksichtigt oder auf Grund von Preisdruck nicht realisiert. DarĂŒber hinaus erschwert die Beschaffenheit der eingesetzten GerĂ€te die Anwendung klassischer Sicherheitsverfahren. So werden in diesem Kontext vorrangig stark auf AnwendungsfĂ€lle zugeschnittene Lösungen realisiert, die auf Grund der verwendeten Hardware meist nur eingeschrĂ€nkte Rechen- und Energieressourcen zur VerfĂŒgung haben.
An dieser Stelle können die AnsĂ€tze und Lösungen der Sicherheit auf physikalischer Schicht (physical layer security, PLS) eine Alternative zu klassischer KryptograïŹe bieten. Im Kontext der drahtlosen Kommunikation können hier die Eigenschaften des Ăbertragungskanals zwischen zwei legitimen Kommunikationspartnern genutzt werden, um Sicherheitsprimitive zu implementieren und damit Sicherheitsziele zu realisieren. Konkret können etwa reziproke Kanaleigenschaften verwendet werden, um einen Vertrauensanker in Form eines geteilten, symmetrischen Geheimnisses zu generieren. Dieses Verfahren wird SchlĂŒsselgenerierung basierend auf KanalreziprozitĂ€t (channel reciprocity based key generation, CRKG) genannt.
Auf Grund der weitreichenden VerfĂŒgbarkeit wird dieses Verfahren meist mit Hilfe der Kanaleigenschaft des EmpfangsstĂ€rkenindikators (received signal strength indicator, RSSI) realisiert. Dies hat jedoch den Nachteil, dass alle physikalischen Kanaleigenschaften auf einen einzigen Wert heruntergebrochen werden und somit ein GroĂteil der verfĂŒgbaren Informationen vernachlĂ€ssigt wird.
Dem gegenĂŒber steht die Verwendung der vollstĂ€ndigen Kanalzustandsinformationen (channel state information, CSI). Aktuelle technische Entwicklungen ermöglichen es zunehmend, diese Informationen auch in AlltagsgerĂ€ten zur VerfĂŒgung zu stellen und somit fĂŒr PLS weiterzuverwenden.
In dieser Arbeit analysieren wir Fragestellungen, die sich aus einem Wechsel hin zu CSI als verwendetes SchlĂŒsselmaterial ergeben. Konkret untersuchen wir CSI in Form von Ultrabreitband-Kanalimpulsantworten (channel impulse response, CIR).
FĂŒr die Untersuchungen haben wir initial umfangreiche Messungen vorgenommen und damit analysiert, in wie weit die grundlegenden Annahmen von PLS und CRKG erfĂŒllt sind und die CIRs sich grundsĂ€tzlich fĂŒr die SchlĂŒsselgenerierung eignen. Hier zeigen wir, dass die CIRs der legitimen Kommunikationspartner eine höhere Ăhnlichkeit als die eines Angreifers aufzeigen und das somit ein Vorteil gegenĂŒber diesem auf der physikalischen Schicht besteht, der fĂŒr die SchlĂŒsselgenerierung ausgenutzt werden kann.
Basierend auf den Ergebnissen der initialen Untersuchung stellen wir dann grundlegende Verfahren vor, die notwendig sind, um die Ăhnlichkeit der legitimen Messungen zu verbessern und somit die SchlĂŒsselgenerierung zu ermöglichen. Konkret werden Verfahren vorgestellt, die den zeitlichen Versatz zwischen reziproken Messungen entfernen und somit die Ăhnlichkeit erhöhen, sowie Verfahren, die das in den Messungen zwangslĂ€uïŹg vorhandene Rauschen entfernen.
Gleichzeitig untersuchen wir, inwieweit die getroffenen fundamentalen Sicherheitsannahmen aus Sicht eines Angreifers erfĂŒllt sind. Zu diesem Zweck prĂ€sentieren, implementieren und analysieren wir verschiedene praktische Angriffsmethoden. Diese Verfahren umfassen etwa AnsĂ€tze, bei denen mit Hilfe von deterministischen Kanalmodellen oder durch ray tracing versucht wird, die legitimen CIRs vorherzusagen. Weiterhin untersuchen wir Machine Learning AnsĂ€tze, die darauf abzielen, die legitimen CIRs direkt aus den Beobachtungen eines Angreifers zu inferieren. Besonders mit Hilfe des letzten Verfahrens kann hier gezeigt werden, dass groĂe Teile der CIRs deterministisch vorhersagbar sind. Daraus leitet sich der Schluss ab, dass CIRs nicht ohne adĂ€quate Vorverarbeitung als Eingabe fĂŒr Sicherheitsprimitive verwendet werden sollten.
Basierend auf diesen Erkenntnissen entwerfen und implementieren wir abschlieĂend Verfahren, die resistent gegen die vorgestellten Angriffe sind. Die erste Lösung baut auf der Erkenntnis auf, dass die Angriffe aufgrund von vorhersehbaren Teilen innerhalb der CIRs möglich sind. Daher schlagen wir einen klassischen Vorverarbeitungsansatz vor, der diese deterministisch vorhersagbaren Teile entfernt und somit das Eingabematerial absichert. Wir implementieren und analysieren diese Lösung und zeigen ihre EffektivitĂ€t sowie ihre Resistenz gegen die vorgeschlagenen Angriffe. In einer zweiten Lösung nutzen wir die FĂ€higkeiten des maschinellen Lernens, indem wir sie ebenfalls in das Systemdesign einbringen. Aufbauend auf ihrer starken Leistung bei der Mustererkennung entwickeln, implementieren und analysieren wir eine Lösung, die lernt, die zufĂ€lligen Teile aus den rohen CIRs zu extrahieren, durch die die KanalreziprozitĂ€t deïŹniert wird, und alle anderen, deterministischen Teile verwirft. Damit ist nicht nur das SchlĂŒsselmaterial gesichert, sondern gleichzeitig auch der Abgleich des SchlĂŒsselmaterials, da Differenzen zwischen den legitimen Beobachtungen durch die Merkmalsextraktion eïŹzient entfernt werden. Alle vorgestellten Lösungen verzichten komplett auf den Austausch von Informationen zwischen den legitimen Kommunikationspartnern, wodurch der damit verbundene InformationsabïŹuss sowie Energieverbrauch inhĂ€rent vermieden wird
Context and communication profiling for IoT security and privacy: techniques and applications
During the last decade, two major technological changes have profoundly changed the way in which users consume and interact with on-line services and applications. The first of these has been the success of mobile computing, in particular that of smartphones, the primary end device used by many users for access to the Internet and various applications. The other change is the emergence of the so-called Internet-of-Things (IoT), denoting a technological transition in which everyday objects like household appliances that traditionally have been seen as stand-alone devices, are given network connectivity by introducing digital communication capabilities to those devices. The topic of this dissertation is related to a core challenge that the emergence of these technologies is introducing: how to effectively manage the security and privacy settings of users and devices in a user-friendly manner in an environment in which an ever-growing number of heterogeneous devices live and co-exist with each other?
In particular we study approaches for utilising profiling of contextual parameters and device communications
in order to make autonomous security decisions with the goal of striking a better balance between a system's security on one hand, and, its usability on the other. We introduce four distinct novel approaches utilising profiling for this end. First, we introduce ConXsense, a system demonstrating the use of user-specific longitudinal profiling of contextual information for modelling the usage context of mobile computing devices. Based on this ConXsense can probabilistically automate security policy decisions affecting security settings of the device.
Further we develop an approach utilising the similarity of contextual parameters observed with on-board sensors of co-located devices to construct proofs of presence that are resilient to context-guessing attacks by adversaries that seek to fool a device into believing the adversary is co-located with it, even though it is in reality not.
We then extend this approach to a context-based key evolution approach that allows IoT devices that are co-present in the same physical environment like the same room to use passively observed context measurements to iteratively authenticate their co-presence and thus gradually establish confidence in the other device being part of the same trust domain, e.g., the set of IoT devices in a user's home. We further analyse the relevant constraints that need to be taken into account to ensure security and usability of context-based authentication.
In the final part of this dissertation we extend the profiling approach to network communications of IoT devices and utilise it to realise the design of the IoTSentinel system for autonomous security policy adaptation in IoT device networks. We show that by monitoring the inherent network traffic of IoT devices during their initial set-up, we can automatically identify the type of device newly added to the network. The device-type information is then used by IoTSentinel to adapt traffic filtering rules automatically to provide isolation of devices that are potentially vulnerable to known attacks, thereby protecting the device itself and the rest of the network from threats arising from possible compromise of vulnerable devices
Security in Distributed, Grid, Mobile, and Pervasive Computing
This book addresses the increasing demand to guarantee privacy, integrity, and availability of resources in networks and distributed systems. It first reviews security issues and challenges in content distribution networks, describes key agreement protocols based on the Diffie-Hellman key exchange and key management protocols for complex distributed systems like the Internet, and discusses securing design patterns for distributed systems. The next section focuses on security in mobile computing and wireless networks. After a section on grid computing security, the book presents an overview of security solutions for pervasive healthcare systems and surveys wireless sensor network security
Reed solomon codes for the reconciliation of wireless PHY layer based secret keys
This paper proposes a key reconciliation mechanism using Reed Solomon code to improve the effectiveness of secret key generation based on Received Signal Strength (RSS) variations in a wireless channel between two communicating parties. We use a two threshold quantization algorithm which can operate as a lossless system improving the secret bit extraction rate. We present our Reed Solomon (RS) code based algorithm for reconciling the independently derived secret keys through sharing of only the syndrome bits. We evaluate our reconciliation algorithm using simulated channel measurements and real environment data gathered between an unmanned aerial vehicle (UAV) and a controller in a semi mobile environment. We show that by selecting appropriate parameters of the RS code, it is possible to generate matching keys at the transmitter and the receiver which can be used to secure the communication at wireless PHY or upper layers
Instruments for New Music: Sound, Technology, and Modernism
Player pianos, radio-electric circuits, gramophone records, and optical sound filmâthese were the cutting-edge acoustic technologies of the early twentieth century, and for many musicians and artists of the time, these devices were also the implements of a musical revolution. Instruments for New Music traces a diffuse network of cultural agents who shared the belief that a truly modern music could be attained only through a radical challenge to the technological foundations of the art. Centered in Germany during the 1920s and 1930s, the movement to create new instruments encompassed a broad spectrum of experiments, from the exploration of microtonal tunings and exotic tone colors to the ability to compose directly for automatic musical machines. This movement comprised composers, inventors, and visual artists, including Paul Hindemith, Ernst Toch, Jörg Mager, Friedrich Trautwein, LĂĄszlĂł Moholy-Nagy, Walter Ruttmann, and Oskar Fischinger. Pattesonâs fascinating study combines an artifact-oriented history of new music in the early twentieth century with an astute revisiting of still-relevant debates about the relationship between technology and the arts
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