Acoustic Integrity Codes: Secure Device Pairing Using Short-Range Acoustic Communication

Secure Device Pairing (SDP) relies on an out-of-band channel to authenticate devices. This requires a common hardware interface, which limits the use of existing SDP systems. We propose to use short-range acoustic communication for the initial pairing. Audio hardware is commonly available on existing off-the-shelf devices and can be accessed from user space without requiring firmware or hardware modifications. We improve upon previous approaches by designing Acoustic Integrity Codes (AICs): a modulation scheme that provides message authentication on the acoustic physical layer. We analyze their security and demonstrate that we can defend against signal cancellation attacks by designing signals with low autocorrelation. Our system can detect overshadowing attacks using a ternary decision function with a threshold. In our evaluation of this SDP scheme's security and robustness, we achieve a bit error ratio below 0.1% for a net bit rate of 100 bps with a signal-to-noise ratio (SNR) of 14 dB. Using our open-source proof-of-concept implementation on Android smartphones, we demonstrate pairing between different smartphone models.Comment: 11 pages, 11 figures. Published at ACM WiSec 2020 (13th ACM Conference on Security and Privacy in Wireless and Mobile Networks). Updated reference

A Simplified Secure Programming Platform for Internet of Things Devices

The emerging Internet of Things (IoT) revolution has introduced many useful applications that are utilized in our daily lives. Users can program these devices in order to develop their own IoT applications; however, the platforms and languages that are used during development are abounding, complicated, and time-consuming. The software solution provided in this thesis, PROVIZ+, is a secure sensor application development software suite that helps users create sophisticated and secure IoT applications with little software and hardware experience. Moreover, a simple and efficient domain-specific programming language, namely Panther language, was designed for IoT application development to unify existing programming languages. In addition to these contributions, PROVIZ+ supports a novel secure over-the-air programming framework, namely SOTA, using Bluetooth and WiFi as well as serial programming. In this thesis, we explain the features of PROVIZ+’s components, how these tools can help develop IoT applications, and SOTA. We also present the performance evaluations of PROVIZ+ and SOTA

Continuous User Authentication Using Multi-Modal Biometrics

It is commonly acknowledged that mobile devices now form an integral part of an individual’s everyday life. The modern mobile handheld devices are capable to provide a wide range of services and applications over multiple networks. With the increasing capability and accessibility, they introduce additional demands in term of security. This thesis explores the need for authentication on mobile devices and proposes a novel mechanism to improve the current techniques. The research begins with an intensive review of mobile technologies and the current security challenges that mobile devices experience to illustrate the imperative of authentication on mobile devices. The research then highlights the existing authentication mechanism and a wide range of weakness. To this end, biometric approaches are identified as an appropriate solution an opportunity for security to be maintained beyond point-of-entry. Indeed, by utilising behaviour biometric techniques, the authentication mechanism can be performed in a continuous and transparent fashion. This research investigated three behavioural biometric techniques based on SMS texting activities and messages, looking to apply these techniques as a multi-modal biometric authentication method for mobile devices. The results showed that linguistic profiling; keystroke dynamics and behaviour profiling can be used to discriminate users with overall Equal Error Rates (EER) 12.8%, 20.8% and 9.2% respectively. By using a combination of biometrics, the results showed clearly that the classification performance is better than using single biometric technique achieving EER 3.3%. Based on these findings, a novel architecture of multi-modal biometric authentication on mobile devices is proposed. The framework is able to provide a robust, continuous and transparent authentication in standalone and server-client modes regardless of mobile hardware configuration. The framework is able to continuously maintain the security status of the devices. With a high level of security status, users are permitted to access sensitive services and data. On the other hand, with the low level of security, users are required to re-authenticate before accessing sensitive service or data

A wireless multicast delivery architecture for mobile terminals

Content delivery over the Internet to a large number of mobile users offers interesting business opportunities for content providers, intermediaries, and access network operators. A user could receive, for example, music or a digital newspaper directly to a mobile device over wireless networks. Currently, content delivery over the Internet is held back by a number of reasons. Existing network technologies, such as GPRS, have a very limited capacity to transfer large files, such as those required for good-quality pictures in a newspaper. Another problem is security. Content received over the Internet is very vulnerable to being forged. A user who cannot be certain about the source and consistency of the received stock quotes is unlikely to pay for the information. Furthermore, content providers are unwilling to distribute their valuable information over the Internet due to their fear of copyright infringements. Traditionally, content has been considered consumed as soon as it has been downloaded. Content providers have been keen on preventing their content from being transferred over peer-to-peer networks because they consider the delivery itself to be a copyright infringement. In this dissertation, content delivery is separated from content consumption by encrypting the content before delivery. When the users wishes to consume the content, a license which includes the decryption key is provided. The architecture allows content to be delivered to users' devices even before the user commits to consume the content. The user can choose to receive content whenever downloading it is the most convenient and affordable. Thus, the content providers are able to maintain control over the use of their information even after the data has been transferred to the users' terminals. In addition, content received by users can be strongly source authenticated. The architecture allows secure, efficient and reliable delivery of content to a large group of receivers. The architecture does not commit itself to any specific delivery technique, and the content can be delivered using any delivery technique including multicast, broadcast, unicast, and peer-to-peer. This dissertation focuses mostly on multicast as the delivery technique. The efficiency of the multicast delivery over unreliable heterogenous wireless access networks is thoroughly analyzed. Mobile terminals can seamlessly switch between access points and access technologies while continuing to receive data reliably from the network. The multicast delivery uses adaptive error correction and retransmissions to deliver the content as efficiently as possible to a very large number of receivers. The simulations show, that the vast majority of receivers are able to receive the content reliably with a small delay even when the radio network suffers from high packet loss probability. Although the architecture is designed to deliver content to mobile terminals, it is also suitable for delivering content to terminals with fixed Internet connectivity.Digitaalisen sisällön siirtäminen liikkuville käyttäjille Internetin yli tarjoaa uusia liiketoimintamahdollisuuksia niin sisällöntuottajille, välittäjille kuin verkko-operaattoreille. Teknikkaa voidaan käyttää esimerkiksi musiikin tai sähköisten lehtien välittämiseen käyttäjille langattoman verkon kautta. Sisällön välittämistä Internetin kautta hankaloittaa yhä usea seikka. Nykyisin laajassa käytössä olevat verkkotekniikat, kuten GPRS, ovat liian hitaita siirtämään hyvin suuria tiedostoja suurelle määrällä vastaanottajia. Lisäksi väärennetyn tiedon välittäminen Internetin kautta on erittäin helppoa. Sisältö, jonka aitoudesta ja alkuperästä ei ole varmuutta, on usein arvotonta käyttäjälle. Sisällöntuottajat puolestaan ovat haluttomia käyttämään sisältönsä levittämiseen Internetiä mikäli digitaalisesti levitettävän sisällön kopioiminen ja oikeudeton kuluttaminen on liian helppoa. Perinteisesti sisältö ajatellaankin kulutetuksi jo sillä hetkellä, kun se on siirretty käyttäjän laitteeseen. Sen vuoksi sisällön tuottajat ovatkin käyttäneet paljon resursejaan estääkseen sisältönsä välittämisen vertaisverkoissa, koska jo pelkkää sisällön siirtämistä pidetään tekijänoikeusrikkomuksena. Tässä työssä erotetaan sisällön siirtäminen sisällön kuluttamisesta suojaamalla sisältö salauksella ennen sen siirtämistä käyttäjille ja sallimalla vapaa salatun sisällön jakelu. Arkkitehtuuri mahdollistaa sisällön siirtämisen käyttäjien laitteille silloin kun sisällön siirtäminen on edullisinta ja tehokkainta. Vasta käyttäjän halutessa kuluttaa aiemmin lataamaansa sisältöä, tarkistetaan oikeis sisällön käyttöön. Arkkitehtuuri mahdollistaa myös ladatun sisällön alkuperän ja eheyden vahvan tarkistamisen. Arkkitehtuuri mahdollistaa turvallisen, tehokkaan ja luotettavan sisällön siirtämisen suurelle määrälle vastaanottajia. Arkkitehtuuri ei pakota sisällön jakelua käyttämään mitään tiettyä siirtomenetelmää vaan sisältö voidaan siirtää käyttäen esimerkiksi ryhmälähetystä (multicast), joukkolähetystä (broadcast), täsmälähetystä (unicast) tai vertaisverkkoja (peer-to-peer). Tässä työssä on keskitytty analysoimaan ryhmälähetyksen soveltuvuutta tiedon siirtomenetelmänä. Ryhmälähetysmenetelmän tehokkuutta on analysoitu siirrettäessä sisältöä heterogeenisen langattoman liityntäverkon yli. Liikkuvat päätelaitteet voivat siirtyä saumattomasti liityntäverkosta toiseen samalla kun ne vastaanottavat sisältöä. Ryhmälähetys hyödyntää adaptiivista virheenkorjausta ja uudelleenlähetyksiä siirtääkseen sisällönmahdollisimman tehokkaasti suurelle joukolle vastaanottajia. Simulaatiot osoittavat, että erittäin suuri osa vastaanottajista saa sisällön luotettavasti ja pienellä viiveellä vaikka liityntäverkossa pakettien virhetodennäköisyys olisi suuri. Arkkitehtuuri on suunniteltu siirtämään sisältöä liikkuville laitteille, mutta sitä voidaan käyttää yhtä hyvin myös kiinteään verkkoon liitettyjen laitteiden kanssa.reviewe

Key management for wireless sensor network security

Wireless Sensor Networks (WSNs) have attracted great attention not only in industry but also in academia due to their enormous application potential and unique security challenges. A typical sensor network can be seen as a combination of a number of low-cost sensor nodes which have very limited computation and communication capability, memory space, and energy supply. The nodes are self-organized into a network to sense or monitor surrounding information in an unattended environment, while the self-organization property makes the networks vulnerable to various attacks.Many cryptographic mechanisms that solve network security problems rely directly on secure and efficient key management making key management a fundamental research topic in the field of WSNs security. Although key management for WSNs has been studied over the last years, the majority of the literature has focused on some assumed vulnerabilities along with corresponding countermeasures. Specific application, which is an important factor in determining the feasibility of the scheme, has been overlooked to a large extent in the existing literature.This thesis is an effort to develop a key management framework and specific schemes for WSNs by which different types of keys can be established and also can be distributed in a self-healing manner; explicit/ implicit authentication can be integrated according to the security requirements of expected applications. The proposed solutions would provide reliable and robust security infrastructure for facilitating secure communications in WSNs.There are five main parts in the thesis. In Part I, we begin with an introduction to the research background, problems definition and overview of existing solutions. From Part II to Part IV, we propose specific solutions, including purely Symmetric Key Cryptography based solutions, purely Public Key Cryptography based solutions, and a hybrid solution. While there is always a trade-off between security and performance, analysis and experimental results prove that each proposed solution can achieve the expected security aims with acceptable overheads for some specific applications. Finally, we recapitulate the main contribution of our work and identify future research directions in Part V

The InfoSec Handbook

Computer scienc

Usable privacy and security in smart homes

Ubiquitous computing devices increasingly dominate our everyday lives, including our most private places: our homes. Homes that are equipped with interconnected, context-aware computing devices, are considered “smart” homes. To provide their functionality and features, these devices are typically equipped with sensors and, thus, are capable of collecting, storing, and processing sensitive user data, such as presence in the home. At the same time, these devices are prone to novel threats, making our homes vulnerable by opening them for attackers from outside, but also from within the home. For instance, remote attackers who digitally gain access to presence data can plan for physical burglary. Attackers who are physically present with access to devices could access associated (sensitive) user data and exploit it for further cyberattacks. As such, users’ privacy and security are at risk in their homes. Even worse, many users are unaware of this and/or have limited means to take action. This raises the need to think about usable mechanisms that can support users in protecting their smart home setups. The design of such mechanisms, however, is challenging due to the variety and heterogeneity of devices available on the consumer market and the complex interplay of user roles within this context. This thesis contributes to usable privacy and security research in the context of smart homes by a) understanding users’ privacy perceptions and requirements for usable mechanisms and b) investigating concepts and prototypes for privacy and security mechanisms. Hereby, the focus is on two specific target groups, that are inhabitants and guests of smart homes. In particular, this thesis targets their awareness of potential privacy and security risks, enables them to take control over their personal privacy and security, and illustrates considerations for usable authentication mechanisms. This thesis provides valuable insights to help researchers and practitioners in designing and evaluating privacy and security mechanisms for future smart devices and homes, particularly targeting awareness, control, and authentication, as well as various roles.Computer und andere „intelligente“, vernetzte Geräte sind allgegenwärtig und machen auch vor unserem privatesten Zufluchtsort keinen Halt: unserem Zuhause. Ein „intelligentes Heim“ verspricht viele Vorteile und nützliche Funktionen. Um diese zu erfüllen, sind die Geräte mit diversen Sensoren ausgestattet – sie können also in unserem Zuhause sensitive Daten sammeln, speichern und verarbeiten (bspw. Anwesenheit). Gleichzeitig sind die Geräte anfällig für (neuartige) Cyberangriffe, gefährden somit unser Zuhause und öffnen es für potenzielle – interne sowie externe – Angreifer. Beispielsweise könnten Angreifer, die digital Zugriff auf sensitive Daten wie Präsenz erhalten, einen physischen Überfall in Abwesenheit der Hausbewohner planen. Angreifer, die physischen Zugriff auf ein Gerät erhalten, könnten auf assoziierte Daten und Accounts zugreifen und diese für weitere Cyberangriffe ausnutzen. Damit werden die Privatsphäre und Sicherheit der Nutzenden in deren eigenem Zuhause gefährdet. Erschwerend kommt hinzu, dass viele Nutzenden sich dessen nicht bewusst sind und/oder nur limitierte Möglichkeiten haben, effiziente Gegenmaßnahmen zu ergreifen. Dies macht es unabdingbar, über benutzbare Mechanismen nachzudenken, die Nutzende beim Schutz ihres intelligenten Zuhauses unterstützen. Die Umsetzung solcher Mechanismen ist allerdings eine große Herausforderung. Das liegt unter anderem an der großen Vielfalt erhältlicher Geräte von verschiedensten Herstellern, was das Finden einer einheitlichen Lösung erschwert. Darüber hinaus interagieren im Heimkontext meist mehrere Nutzende in verschieden Rollen (bspw. Bewohner und Gäste), was die Gestaltung von Mechanismen zusätzlich erschwert. Diese Doktorarbeit trägt dazu bei, benutzbare Privatsphäre- und Sicherheitsmechanismen im Kontext des „intelligenten Zuhauses“ zu entwickeln. Insbesondere werden a) die Wahrnehmung von Privatsphäre sowie Anforderungen an potenzielle Mechanismen untersucht, sowie b) Konzepte und Prototypen für Privatsphäre- und Sicherheitsmechanismen vorgestellt. Der Fokus liegt hierbei auf zwei Zielgruppen, den Bewohnern sowie den Gästen eines intelligenten Zuhauses. Insbesondere werden in dieser Arbeit deren Bewusstsein für potenzielle Privatsphäre- und Sicherheits-Risiken adressiert, ihnen Kontrolle über ihre persönliche Privatsphäre und Sicherheit ermöglicht, sowie Möglichkeiten für benutzbare Authentifizierungsmechanismen für beide Zielgruppen aufgezeigt. Die Ergebnisse dieser Doktorarbeit legen den Grundstein für zukünftige Entwicklung und Evaluierung von benutzbaren Privatsphäre und Sicherheitsmechanismen im intelligenten Zuhause

Risks and potentials of graphical and gesture-based authentication for touchscreen mobile devices

While a few years ago, mobile phones were mainly used for making phone calls and texting short messages, the functionality of mobile devices has massively grown. We are surfing the web, sending emails and we are checking our bank accounts on the go. As a consequence, these internet-enabled devices store a lot of potentially sensitive data and require enhanced protection. We argue that authentication often represents the only countermeasure to protect mobile devices from unwanted access. Knowledge-based concepts (e.g., PIN) are the most used authentication schemes on mobile devices. They serve as the main protection barrier for many users and represent the fallback solution whenever alternative mechanisms fail (e.g., fingerprint recognition). This thesis focuses on the risks and potentials of gesture-based authentication concepts that particularly exploit the touch feature of mobile devices. The contribution of our work is threefold. Firstly, the problem space of mobile authentication is explored. Secondly, the design space is systematically evaluated utilizing interactive prototypes. Finally, we provide generalized insights into the impact of specific design factors and present recommendations for the design and the evaluation of graphical gesture-based authentication mechanisms. The problem space exploration is based on four research projects that reveal important real-world issues of gesture-based authentication on mobile devices. The first part focuses on authentication behavior in the wild and shows that the mobile context makes great demands on the usability of authentication concepts. The second part explores usability features of established concepts and indicates that gesture-based approaches have several benefits in the mobile context. The third part focuses on observability and presents a prediction model for the vulnerability of a given grid-based gesture. Finally, the fourth part investigates the predictability of user-selected gesture-based secrets. The design space exploration is based on a design-oriented research approach and presents several practical solutions to existing real-world problems. The novel authentication mechanisms are implemented into working prototypes and evaluated in the lab and the field. In the first part, we discuss smudge attacks and present alternative authentication concepts that are significantly more secure against such attacks. The second part focuses on observation attacks. We illustrate how relative touch gestures can support eyes-free authentication and how they can be utilized to make traditional PIN-entry secure against observation attacks. The third part addresses the problem of predictable gesture choice and presents two concepts which nudge users to select a more diverse set of gestures. Finally, the results of the basic research and the design-oriented applied research are combined to discuss the interconnection of design space and problem space. We contribute by outlining crucial requirements for mobile authentication mechanisms and present empirically proven objectives for future designs. In addition, we illustrate a systematic goal-oriented development process and provide recommendations for the evaluation of authentication on mobile devices.Während Mobiltelefone vor einigen Jahren noch fast ausschließlich zum Telefonieren und zum SMS schreiben genutzt wurden, sind die Anwendungsmöglichkeiten von Mobilgeräten in den letzten Jahren erheblich gewachsen. Wir surfen unterwegs im Netz, senden E-Mails und überprüfen Bankkonten. In der Folge speichern moderne internetfähigen Mobilgeräte eine Vielfalt potenziell sensibler Daten und erfordern einen erhöhten Schutz. In diesem Zusammenhang stellen Authentifizierungsmethoden häufig die einzige Möglichkeit dar, um Mobilgeräte vor ungewolltem Zugriff zu schützen. Wissensbasierte Konzepte (bspw. PIN) sind die meistgenutzten Authentifizierungssysteme auf Mobilgeräten. Sie stellen für viele Nutzer den einzigen Schutzmechanismus dar und dienen als Ersatzlösung, wenn alternative Systeme (bspw. Fingerabdruckerkennung) versagen. Diese Dissertation befasst sich mit den Risiken und Potenzialen gestenbasierter Konzepte, welche insbesondere die Touch-Funktion moderner Mobilgeräte ausschöpfen. Der wissenschaftliche Beitrag dieser Arbeit ist vielschichtig. Zum einen wird der Problemraum mobiler Authentifizierung erforscht. Zum anderen wird der Gestaltungsraum anhand interaktiver Prototypen systematisch evaluiert. Schließlich stellen wir generelle Einsichten bezüglich des Einflusses bestimmter Gestaltungsaspekte dar und geben Empfehlungen für die Gestaltung und Bewertung grafischer gestenbasierter Authentifizierungsmechanismen. Die Untersuchung des Problemraums basiert auf vier Forschungsprojekten, welche praktische Probleme gestenbasierter Authentifizierung offenbaren. Der erste Teil befasst sich mit dem Authentifizierungsverhalten im Alltag und zeigt, dass der mobile Kontext hohe Ansprüche an die Benutzerfreundlichkeit eines Authentifizierungssystems stellt. Der zweite Teil beschäftigt sich mit der Benutzerfreundlichkeit etablierter Methoden und deutet darauf hin, dass gestenbasierte Konzepte vor allem im mobilen Bereich besondere Vorzüge bieten. Im dritten Teil untersuchen wir die Beobachtbarkeit gestenbasierter Eingabe und präsentieren ein Vorhersagemodell, welches die Angreifbarkeit einer gegebenen rasterbasierten Geste abschätzt. Schließlich beschäftigen wir uns mit der Erratbarkeit nutzerselektierter Gesten. Die Untersuchung des Gestaltungsraums basiert auf einem gestaltungsorientierten Forschungsansatz, welcher zu mehreren praxisgerechte Lösungen führt. Die neuartigen Authentifizierungskonzepte werden als interaktive Prototypen umgesetzt und in Labor- und Feldversuchen evaluiert. Im ersten Teil diskutieren wir Fettfingerattacken ("smudge attacks") und präsentieren alternative Authentifizierungskonzepte, welche effektiv vor diesen Angriffen schützen. Der zweite Teil beschäftigt sich mit Angriffen durch Beobachtung und verdeutlicht wie relative Gesten dazu genutzt werden können, um blickfreie Authentifizierung zu gewährleisten oder um PIN-Eingaben vor Beobachtung zu schützen. Der dritte Teil beschäftigt sich mit dem Problem der vorhersehbaren Gestenwahl und präsentiert zwei Konzepte, welche Nutzer dazu bringen verschiedenartige Gesten zu wählen. Die Ergebnisse der Grundlagenforschung und der gestaltungsorientierten angewandten Forschung werden schließlich verknüpft, um die Verzahnung von Gestaltungsraum und Problemraum zu diskutieren. Wir präsentieren wichtige Anforderungen für mobile Authentifizierungsmechanismen und erläutern empirisch nachgewiesene Zielvorgaben für zukünftige Konzepte. Zusätzlich zeigen wir einen zielgerichteten Entwicklungsprozess auf, welcher bei der Entwicklung neuartiger Konzepte helfen wird und geben Empfehlungen für die Evaluation mobiler Authentifizierungsmethoden

INFRASTRUCTURE-FREE SECURE PAIRING OF MOBILE DEVICES

Mobile devices have advanced tremendously during the last ten years and have changed our daily life in various ways. Secure pairing of mobile devices has become a significant issue considering the huge quantity of active mobile device connections and mobile traffic. However, current commonly used file sharing mobile applications rely on servers completely that are always targeted by attackers. In this thesis work, an innovative mechanism is proposed to generate symmetric keys on both mobile devices independently from a shared movement in arbitrary pattern, which means no server needs to be involved and no data exchange needed. A secret wireless-communication channel can then be established with a particular network strategy