Secure and Usable User Authentication

Authentication is a ubiquitous task in users\u27 daily lives. The dominant form of user authentication are text passwords. They protect private accounts like online banking, gaming, and email, but also assets in organisations. Yet, many issues are associated with text passwords, leading to challenges faced by both, users and organisations. This thesis contributes to the body of research enabling secure and usable user authentication, benefiting both, users and organisations. To that end, it addresses three distinct challenges. The first challenge addressed in this thesis is the creation of correct, complete, understandable, and effective password security awareness materials. To this end, a systematic process for the creation of awareness materials was developed and applied to create a password security awareness material. This process comprises four steps. First, relevant content for an initial version is aggregated (i.e. descriptions of attacks on passwords and user accounts, descriptions of defences to these attacks, and common misconceptions about password and user account security). Then, feedback from information security experts is gathered to ensure the correctness and completeness of the awareness material. Thereafter, feedback from lay-users is gathered to ensure the understandability of the awareness material. Finally, a formal evaluation of the awareness material is conducted to ensure its effectiveness (i.e. whether the material improves participant\u27s ability to assess the security of passwords as well as password-related behaviour and decreases the prevalence of common misconceptions about password and user account security). The results of the evaluation show the effectiveness of the awareness material: it significantly improved the participants\u27 ability to assess the security of password-related behaviour as well as passwords and significantly decreased the prevalence of misconceptions about password and user account security. The second challenge addressed in this thesis is shoulder-surfing resistant text password entry with gamepads (as an example of very constrained input devices) in shared spaces. To this end, the very first investigation of text password entry with gamepads is conducted. First, the requirements of authentication in the gamepad context are described. Then, these requirements are applied to assess schemes already deployed in the gamepad context and shoulder-surfing resistant authentication schemes from the literature proposed for non-gamepad contexts. The results of this assessment show that none of the currently deployed and only four of the proposals in the literature fulfil all requirements. Furthermore, the results of the assessment also indicate a need for an empirical evaluation in order to exactly gauge the shoulder-surfing threat in the gamepad context and compare alternatives to the incumbent on-screen keyboard. Based on these results, two user studies (one online study and one lab study) are conducted to investigate the shoulder-surfing resistance and usability of three authentication schemes in the gamepad context: the on-screen keyboard (as de-facto standard in this context), the grid-based scheme (an existing proposal from the literature identified as the most viable candidate adaptable to the gamepad context during the assessment), and Colorwheels (a novel shoulder-surfing resistant authentication scheme specifically designed for the gamepad context). The results of these two user studies show that on-screen keyboards are highly susceptible to opportunistic shoulder-surfing, but also show the most favourable usability properties among the three schemes. Colorwheels offers the most robust shoulder-surfing resistance and scores highest with respect to participants\u27 intention to use it in the future, while showing more favourable usability results than the grid-based scheme. The third challenge addressed in this thesis is secure and efficient storage of passwords in portfolio authentication schemes. Portfolio authentication is used to counter capture attacks such as shoulder-surfing or eavesdropping on network traffic. While usability studies of portfolio authentication schemes showed promising results, a verification scheme which allows secure and efficient storage of the portfolio authentication secret had been missing until now. To remedy this problem, the (t,n)-threshold verification scheme is proposed. It is based on secret sharing and key derivation functions. The security as well as the efficiency properties of two variants of the scheme (one based on Blakley secret sharing and one based on Shamir secret sharing) are evaluated against each other and against a naive approach. These evaluations show that the two (t,n)-threshold verification scheme variants always exhibit more favourable properties than the naive approach and that when deciding between the two variants, the exact application scenario must be considered. Three use cases illustrate as exemplary application scenarios the versatility of the proposed (t,n)-threshold verification scheme. By addressing the aforementioned three distinct challenges, this thesis demonstrates the breadth of the field of usable and secure user authentication ranging from awareness materials, to the assessment and evaluation of authentication schemes, to applying cryptography to craft secure password storage solutions. The research processes, results, and insights described in this thesis represent important and meaningful contributions to the state of the art in the research on usable and secure user authentication, offering benefits for users, organisations, and researchers alike

Supporting users in password authentication with persuasive design

Activities like text-editing, watching movies, or managing personal finances are all accomplished with web-based solutions nowadays. The providers need to ensure security and privacy of user data. To that end, passwords are still the most common authentication method on the web. They are inexpensive and easy to implement. Users are largely accustomed to this kind of authentication but passwords represent a considerable nuisance, because they are tedious to create, remember, and maintain. In many cases, usability issues turn into security problems, because users try to work around the challenges and create easily predictable credentials. Often, they reuse their passwords for many purposes, which aggravates the risk of identity theft. There have been numerous attempts to remove the root of the problem and replace passwords, e.g., through biometrics. However, no other authentication strategy can fully replace them, so passwords will probably stay a go-to authentication method for the foreseeable future. Researchers and practitioners have thus aimed to improve users' situation in various ways. There are two main lines of research on helping users create both usable and secure passwords. On the one hand, password policies have a notable impact on password practices, because they enforce certain characteristics. However, enforcement reduces users' autonomy and often causes frustration if the requirements are poorly communicated or overly complex. On the other hand, user-centered designs have been proposed: Assistance and persuasion are typically more user-friendly but their influence is often limited. In this thesis, we explore potential reasons for the inefficacy of certain persuasion strategies. From the gained knowledge, we derive novel persuasive design elements to support users in password authentication. The exploration of contextual factors in password practices is based on four projects that reveal both psychological aspects and real-world constraints. Here, we investigate how mental models of password strength and password managers can provide important pointers towards the design of persuasive interventions. Moreover, the associations between personality traits and password practices are evaluated in three user studies. A meticulous audit of real-world password policies shows the constraints for selection and reuse practices. Based on the review of context factors, we then extend the design space of persuasive password support with three projects. We first depict the explicit and implicit user needs in password support. Second, we craft and evaluate a choice architecture that illustrates how a phenomenon from marketing psychology can provide new insights into the design of nudging strategies. Third, we tried to empower users to create memorable passwords with emojis. The results show the challenges and potentials of emoji-passwords on different platforms. Finally, the thesis presents a framework for the persuasive design of password support. It aims to structure the required activities during the entire process. This enables researchers and practitioners to craft novel systems that go beyond traditional paradigms, which is illustrated by a design exercise.Heutzutage ist es möglich, mit web-basierten Lösungen Texte zu editieren, Filme anzusehen, oder seine persönlichen Finanzen zu verwalten. Die Anbieter müssen hierbei Sicherheit und Vertraulichkeit von Nutzerdaten sicherstellen. Dazu sind Passwörter weiterhin die geläufigste Authentifizierungsmethode im Internet. Sie sind kostengünstig und einfach zu implementieren. NutzerInnen sind bereits im Umgang mit diesem Verfahren vertraut jedoch stellen Passwörter ein beträchtliches Ärgernis dar, weil sie mühsam zu erstellen, einzuprägen, und verwalten sind. Oft werden Usabilityfragen zu Sicherheitsproblemen, weil NutzerInnen Herausforderungen umschiffen und sich einfach zu erratende Zugangsdaten ausdenken. Daneben verwenden sie Passwörter für viele Zwecke wieder, was das Risiko eines Identitätsdiebstals weiter erhöht. Es gibt zahlreiche Versuche die Wurzel des Problems zu beseitigen und Passwörter zu ersetzen, z.B. mit Biometrie. Jedoch kann bisher kein anderes Verfahren sie vollkommen ersetzen, so dass Passwörter wohl für absehbare Zeit die Hauptauthentifizierungsmethode bleiben werden. ExpertInnen aus Forschung und Industrie haben sich deshalb zum Ziel gefasst, die Situation der NutzerInnen auf verschiedene Wege zu verbessern. Es existieren zwei Forschungsstränge darüber wie man NutzerInnen bei der Erstellung von sicheren und benutzbaren Passwörtern helfen kann. Auf der einen Seite haben Regeln bei der Passworterstellung deutliche Auswirkungen auf Passwortpraktiken, weil sie bestimmte Charakteristiken durchsetzen. Jedoch reduziert diese Durchsetzung die Autonomie der NutzerInnen und verursacht Frustration, wenn die Anforderungen schlecht kommuniziert oder übermäßig komplex sind. Auf der anderen Seite stehen nutzerzentrierte Designs: Hilfestellung und Überzeugungsarbeit sind typischerweise nutzerfreundlicher wobei ihr Einfluss begrenzt ist. In dieser Arbeit erkunden wir die potenziellen Gründe für die Ineffektivität bestimmter Überzeugungsstrategien. Von dem hierbei gewonnenen Wissen leiten wir neue persuasive Designelemente für Hilfestellung bei der Passwortauthentifizierung ab. Die Exploration von Kontextfaktoren im Umgang mit Passwörtern basiert auf vier Projekten, die sowohl psychologische Aspekte als auch Einschränkungen in der Praxis aufdecken. Hierbei untersuchen wir inwiefern Mental Modelle von Passwortstärke und -managern wichtige Hinweise auf das Design von persuasiven Interventionen liefern. Darüber hinaus werden die Zusammenhänge zwischen Persönlichkeitsmerkmalen und Passwortpraktiken in drei Nutzerstudien untersucht. Eine gründliche Überprüfung von Passwortregeln in der Praxis zeigt die Einschränkungen für Passwortselektion und -wiederverwendung. Basierend auf der Durchleuchtung der Kontextfaktoren erweitern wir hierauf den Design-Raum von persuasiver Passworthilfestellung mit drei Projekten. Zuerst schildern wir die expliziten und impliziten Bedürfnisse in punkto Hilfestellung. Daraufhin erstellen und evaluieren wir eine Entscheidungsarchitektur, welche veranschaulicht wie ein Phänomen aus der Marketingpsychologie neue Einsichten in das Design von Nudging-Strategien liefern kann. Im Schlussgang versuchen wir NutzerInnen dabei zu stärken, gut merkbare Passwörter mit Hilfe von Emojis zu erstellen. Die Ergebnisse zeigen die Herausforderungen und Potenziale von Emoji-Passwörtern auf verschiedenen Plattformen. Zuletzt präsentiert diese Arbeit ein Rahmenkonzept für das persuasive Design von Passworthilfestellungen. Es soll die benötigten Aktivitäten während des gesamten Prozesses strukturieren. Dies erlaubt ExpertInnen neuartige Systeme zu entwickeln, die über traditionelle Ansätze hinausgehen, was durch eine Designstudie veranschaulicht wird

Secure Authentication for Mobile Users

RÉSUMÉ :L’authentification biométrique telle que les empreintes digitales et la biométrie faciale a changé la principale méthode d’authentification sur les appareils mobiles. Les gens inscrivent facilement leurs modèles d’empreintes digitales ou de visage dans différents systèmes d’authentification pour profiter de leur accès facile au smartphone sans avoir besoin de se souvenir et de saisir les codes PIN/mots de passe conventionnels. Cependant, ils ne sont pas conscients du fait qu’ils stockent leurs caractéristiques physiologiques ou comportementales durables sur des plates-formes non sécurisées (c’est-à-dire sur des téléphones mobiles ou sur un stockage en nuage), menaçant la confidentialité de leurs modèles biométriques et de leurs identités. Par conséquent, un schéma d’authentification est nécessaire pour préserver la confidentialité des modèles biométriques des utilisateurs et les authentifier en toute sécurité sans compter sur des plates-formes non sécurisées et non fiables.La plupart des études ont envisagé des approches logicielles pour concevoir un système d’authentification sécurisé. Cependant, ces approches ont montré des limites dans les systèmes d’authentification sécurisés. Principalement, ils souffrent d’une faible précision de vérification, en raison des transformations du gabarit (cancelable biometrics), de la fuite d’informations (fuzzy commitment schemes) ou de la réponse de vérification non en temps réel, en raison des calculs coûteux (homomorphic encryption).---------- ABSTRACT: Biometric authentication such as fingerprint and face biometrics has changed the main authentication method on mobile devices. People easily enroll their fingerprint or face template on different authentication systems to take advantage of their easy access to the smartphone with no need to remember and enter the conventional PINs/passwords. However, they are not aware that they store their long-lasting physiological or behavioral characteristics on insecure platforms (i.e., on mobile phones or on cloud storage), threatening the privacy of their biometric templates and their identities. Therefore, an authentication scheme is required to preserve the privacy of users’ biometric templates and securely authenticate them without relying on insecure and untrustworthy platforms. Most studies have considered software-based approaches to design a privacy-reserving authentication system. However, these approaches have shown limitations in secure authentication systems. Mainly, they suffer from low verification accuracy, due to the template transformations (in cancelable biometrics), information leakage (in fuzzy commitment schemes), or non real-time verification response, due to the expensive computations (in homomorphic encryption)

Cryptography and Computer Communications Security. Extending the Human Security Perimeter through a Web of Trust

This work modifies Shamir’s algorithm by sharing a random key that is used to lock up the secret data; as against sharing the data itself. This is significant in cloud computing, especially with homomorphic encryption. Using web design, the resultant scheme practically globalises secret sharing with authentications and inherent secondary applications. The work aims at improving cybersecurity via a joint exploitation of human factors and technology; a human-centred cybersecurity design as opposed to technology-centred. The completed functional scheme is tagged CDRSAS. The literature on secret sharing schemes is reviewed together with the concepts of human factors, trust, cyberspace/cryptology and an analysis on a 3-factor security assessment process. This is followed by the relevance of passwords within the context of human factors. The main research design/implementation and system performance are analysed, together with a proposal for a new antidote against 419 fraudsters. Two twin equations were invented in the investigation process; a pair each for secret sharing and a risk-centred security assessment technique. The building blocks/software used for the CDRSAS include Shamir’s algorithm, MD5, HTML5, PHP, Java, Servlets, JSP, Javascript, MySQL, JQuery, CSS, MATLAB, MS Excel, MS Visio, and Photoshop. The codes are developed in Eclipse IDE, and the Java-based system runs on Tomcat and Apache, using XAMPP Server. Its code units have passed JUnit tests. The system compares favourably with SSSS. Defeating socio-cryptanalysis in cyberspace requires strategies that are centred on human trust, trust-related human attributes, and technology. The PhD research is completed but there is scope for future work.Petroleum Technology Development Fund (PTDF), Abuja, Nigeria

Privacy-aware Security Applications in the Era of Internet of Things

In this dissertation, we introduce several novel privacy-aware security applications. We split these contributions into three main categories: First, to strengthen the current authentication mechanisms, we designed two novel privacy-aware alternative complementary authentication mechanisms, Continuous Authentication (CA) and Multi-factor Authentication (MFA). Our first system is Wearable-assisted Continuous Authentication (WACA), where we used the sensor data collected from a wrist-worn device to authenticate users continuously. Then, we improved WACA by integrating a noise-tolerant template matching technique called NTT-Sec to make it privacy-aware as the collected data can be sensitive. We also designed a novel, lightweight, Privacy-aware Continuous Authentication (PACA) protocol. PACA is easily applicable to other biometric authentication mechanisms when feature vectors are represented as fixed-length real-valued vectors. In addition to CA, we also introduced a privacy-aware multi-factor authentication method, called PINTA. In PINTA, we used fuzzy hashing and homomorphic encryption mechanisms to protect the users\u27 sensitive profiles while providing privacy-preserving authentication. For the second privacy-aware contribution, we designed a multi-stage privacy attack to smart home users using the wireless network traffic generated during the communication of the devices. The attack works even on the encrypted data as it is only using the metadata of the network traffic. Moreover, we also designed a novel solution based on the generation of spoofed traffic. Finally, we introduced two privacy-aware secure data exchange mechanisms, which allow sharing the data between multiple parties (e.g., companies, hospitals) while preserving the privacy of the individual in the dataset. These mechanisms were realized with the combination of Secure Multiparty Computation (SMC) and Differential Privacy (DP) techniques. In addition, we designed a policy language, called Curie Policy Language (CPL), to handle the conflicting relationships among parties. The novel methods, attacks, and countermeasures in this dissertation were verified with theoretical analysis and extensive experiments with real devices and users. We believe that the research in this dissertation has far-reaching implications on privacy-aware alternative complementary authentication methods, smart home user privacy research, as well as the privacy-aware and secure data exchange methods

Toward Effective Access Control Using Attributes and Pseudoroles

Sharing of information is fundamental to modern computing environments across many application domains. Such information sharing, however, raises security and privacy concerns that require effective access control to prevent unauthorized access and ensure compliance with various laws and regulations. Current approaches such as Role-Based Access Control (RBAC), and Attribute-Based Access Control (ABAC) and their variants are inadequate. Although it provides simple administration of access control and user revocation and permission review, RBAC demands complex initial role engineering and makes access control static. ABAC, on the other hand, simplifies initial security setup and enables flexible access control, but increases the complexity of managing privileges, user revocation and user permissions review. These limitations of RBAC and ABAC have thus motivated research into the development of newer models that use attributes and policies while preserving RBAC\u27s advantages. This dissertation explores the role of attributes---characteristics of entities in the system---in achieving effective access control. The first contribution of this dissertation is the design and development of a secure access system using Ciphertext-Policy Attribute-Based Encryption (CP-ABE). The second contribution is the design and validation of a two-step access control approach, the BiLayer Access Control (BLAC) model. The first layer in BLAC checks whether subjects making access requests have the right BLAC pseudoroles---a pseudorole is a predefined subset of a subject\u27s static attributes. If requesting subjects hold the right pseudoroles, the second layer checks rule(s) within associated BLAC policies for further constraints on access. BLAC thus makes use of attributes effectively while preserving RBAC\u27s advantages. The dissertation\u27s third contribution is the design and definition of an evaluation framework for time complexity analysis, and uses this framework to compare BLAC model with RBAC and ABAC. The fourth contribution is the design and construction of a generic access control threat model, and applying it to assess the effectiveness of BLAC, RBAC and ABAC in mitigating insider threats

Applying Machine Learning to enhance payments systems security

Ph. D. Thesis.During the last two decades, the economic losses because fraudulent card payment transactions have tripled. The significant percentage of losses is because of fraud on e-commerce transactions. Nowadays, there is a clear trend to use more and more mobile devices to make electronic purchases, and it is estimated that this trend will continue in the coming years. In the card payment scheme, big financial institutions process millions of transactions every day; thus, they can model the processed transactions to predict fraud. On the other hand, merchants process a much lower number of transactions, but they have access to valuable information that they can collect from the devices that users utilise during the transaction. In this thesis, we propose a series of measures to enhance the security of these two scenarios based on past transactional data and information collected from the users’ device. Most of the approaches proposed so far to model processed transactions were based on supervised Machine Learning techniques. We propose a fraud detection system for card payments based on an unsupervised machine learning technique; thus, the system may be able to recognise new patterns of fraud. On the other hand, we are looking far ahead, and because of the increment of use of mobile devices to conduct payments, we propose a series of measures to enhance the security of the mobile payment system. We have proposed a user identification and verification systems for smartphones. We base the identification and verification systems on motion data, so the systems will not require any explicit action from users

The role of effort in security and privacy behaviours online

As more and more aspects of users’ lives go online, they can interact with each other, access services and purchase goods with unprecedented convenience and speed. However, this also means that users’ devices and data become more vulnerable to attacks. As security is often added to tools and services as an after-thought, it tends to be poorly integrated into the processes and part of the effort of securing is often offloaded onto the user. Users are goal-driven and they go online to get things done, protecting their security and privacy might therefore not be a priority. The six studies described in this dissertation examine the role of effort in users’ security and privacy behaviours online. First, two security studies use authentication diaries to examine the user effort required for authentication to organisational and online banking systems respectively. Second, two further studies are laboratory evaluations of proposed mechanisms for authentication and verification. Third, two privacy studies examine the role of effort in users’ information disclosure in webforms and evaluate a possible solution that could help users manage how much they disclose. All studies illustrate the different coping strategies users develop to manage their effort. They show that demanding too much effort can affect productivity, cause frustration and undermine the security these mechanisms were meant to offer. The work stresses the importance of conducting methodologically robust user evaluations of both proposed and deployed mechanisms in order to improve user satisfaction and their security and privacy

Европейский и национальный контексты в научных исследованиях

В настоящем электронном сборнике «Европейский и национальный контексты в научных исследованиях. Технология» представлены работы молодых ученых по геодезии и картографии, химической технологии и машиностроению, информационным технологиям, строительству и радиотехнике. Предназначены для работников образования, науки и производства. Будут полезны студентам, магистрантам и аспирантам университетов.=In this Electronic collected materials “National and European dimension in research. Technology” works in the fields of geodesy, chemical technology, mechanical engineering, information technology, civil engineering, and radio-engineering are presented. It is intended for trainers, researchers and professionals. It can be useful for university graduate and post-graduate students