Efficient and Secure Implementations of Lightweight Symmetric Cryptographic Primitives

This thesis is devoted to efficient and secure implementations of lightweight symmetric cryptographic primitives for resource-constrained devices such as wireless sensors and actuators that are typically deployed in remote locations. In this setting, cryptographic algorithms must consume few computational resources and withstand a large variety of attacks, including side-channel attacks. The first part of this thesis is concerned with efficient software implementations of lightweight symmetric algorithms on 8, 16, and 32-bit microcontrollers. A first contribution of this part is the development of FELICS, an open-source benchmarking framework that facilitates the extraction of comparative performance figures from implementations of lightweight ciphers. Using FELICS, we conducted a fair evaluation of the implementation properties of 19 lightweight block ciphers in the context of two different usage scenarios, which are representatives for common security services in the Internet of Things (IoT). This study gives new insights into the link between the structure of a cryptographic algorithm and the performance it can achieve on embedded microcontrollers. Then, we present the SPARX family of lightweight ciphers and describe the impact of software efficiency in the process of shaping three instances of the family. Finally, we evaluate the cost of the main building blocks of symmetric algorithms to determine which are the most efficient ones. The contributions of this part are particularly valuable for designers of lightweight ciphers, software and security engineers, as well as standardization organizations. In the second part of this work, we focus on side-channel attacks that exploit the power consumption or the electromagnetic emanations of embedded devices executing unprotected implementations of lightweight algorithms. First, we evaluate different selection functions in the context of Correlation Power Analysis (CPA) to infer which operations are easy to attack. Second, we show that most implementations of the AES present in popular open-source cryptographic libraries are vulnerable to side-channel attacks such as CPA, even in a network protocol scenario where the attacker has limited control of the input. Moreover, we describe an optimal algorithm for recovery of the master key using CPA attacks. Third, we perform the first electromagnetic vulnerability analysis of Thread, a networking stack designed to facilitate secure communication between IoT devices. The third part of this thesis lies in the area of side-channel countermeasures against power and electromagnetic analysis attacks. We study efficient and secure expressions that compute simple bitwise functions on Boolean shares. To this end, we describe an algorithm for efficient search of expressions that have an optimal cost in number of elementary operations. Then, we introduce optimal expressions for first-order Boolean masking of bitwise AND and OR operations. Finally, we analyze the performance of three lightweight block ciphers protected using the optimal expressions

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

Physical attacks on pairing-based cryptography

In dieser Dissertation analysieren wir Schwächen paarungsbasierter kryptographischer Verfahren gegenüber physikalischen Angriffen wie Seitenkanalangriffen und Fehlerangriffen. Verglichen mit weitverbreiteten Primitiven, beispielsweise basierend auf elliptischen Kurven, ist noch relativ wenig über Angriffsmöglichkeiten aufpaarungsbasierte Verfahren bekannt. Ein Grund dafür ist die hohe Komplexität paarungsbasierter Kryptographie und fehlende Standards für die Festlegung von Parametern, Algorithmen und Verfahren. Des Weiteren läßt sich Wissen aus dem Zusammenhang mit elliptischen Kurven aufgrundstruktureller Unterschiede nicht direkt übertragen. Um ein besseres Verständnis des Problems zu erlangen, präsentieren wir in dieser Arbeit neue physikalische Angriffe auf paarungsbasierte Kryptographie. Unsere Ergebnisse, einschließlich deren praktische Umsetzung, machen deutlich, dass physikalische Angriffe eine Gefahr für die Implementierung paarungsbasierter kryptographischer Verfahren darstellen. Diese Gefahr sollte weiter untersucht und bei der Realisierung dieser Verfahren berücksichtig werden. Weiterhin zeigen unsere Ergebnisse, dass eine Einigung über verwendete Parameter, Algorithmen und Verfahren erzielt werden sollte, um die Komplexität von paarungsbasierter Kryptographie hinischtlich physikalische rAngriffe zu vermindern.In this thesis, we analyze the vulnerability of pairing-based cryptographic schemes against physical attacks like side-channel attacks (SCAs) or fault attacks (FAs). Compared to well-established cryptographic schemes, for example, from standard elliptic curve cryptography (ECC), less is known about weaknesses of pairing-based cryptography (PBC) against those attacks. Reasons for this shortcoming are the complexity of PBC and a missing consensus on parameters, algorithms, and schemes,e.g., in the form of standards. Furthermore, the structural difference between ECC and PBC prevents a direct application of the results from ECC. To get a better understanding of the subject, we present new physical attacks on PBC. Our results, including the practical realizations of our attacks, show that physical attacks are a threat for PBC and need further investigation. Our work also shows that the community should agree on parameters, algorithms, and schemes to reduce the complexity of PBC with respect to physical attacks.Peter Günther ; Supervisor: Prof. Dr. rer. nat. Johannes BlömerTag der Verteidigung: 14.03.2016Universität Paderborn, Univ., Dissertation, 201