10 research outputs found

    Critical analyses of some public-key cryptosystems for high-speed satellite transmission applications

    Get PDF
    Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1981.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.Vita.Bibliography: leaves 83-86.by Moses Hsingwen Ma.M.S

    Physical Security of Cryptographic Algorithm Implementations

    Get PDF
    This thesis deals with physical attacks on implementations of cryptographic algorithms and countermeasures against these attacks. Physical attacks exploit properties of an implementation to recover secret cryptographic keys. Particularly vulnerable to physical attacks are embedded devices. In the area of side-channel analysis, this thesis addresses attacks that exploit observations of power consumption or electromagnetic leakage of the device and target symmetric cryptographic algorithms. First, this work proposes a new combination of two well-known attacks that is more efficient than each of the attacks individually. Second, this work studies attacks exploiting leakage induced by microprocessor cache mechanism, suggesting an algorithm that can recover the secret key in the presence of uncertainties in cache event detection from side-channel acquisitions. Third, practical side-channel attacks are discovered against the AES engine of the AVR XMEGA, a recent versatile microcontroller. In the area of fault analysis, this thesis extends existing attacks against the RSA digital signature algorithm implemented with the Chinese remainder theorem to a setting where parts of the signed message are unknown to the attacker. The new attacks are applicable in particular to several widely used standards in modern smart card applications. In the area of countermeasures, this work proposes a new algorithm for random delay generation in embedded software. The new algorithm is more efficient than the previously suggested algorithms since it introduces more uncertainty for the attacker with less performance overhead. The results presented in this thesis are practically validated in experiments with general-purpose 8-bit AVR and 32-bit ARM microcontrollers that are used in many embedded devices

    Cryptography and its application to operating system security

    Get PDF
    Not provided

    Efficient and Secure Implementations of Lightweight Symmetric Cryptographic Primitives

    Get PDF
    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

    The Role of Female Cryptanalysts from 1914 to 1946

    Get PDF
    This thesis shows that the history of cryptanalysis in Britain in the first half of the twentieth century has focussed on the contribution of men to the virtual exclusion of that of women, and produces evidence to prove that, from the First World War onwards, women, although in a minority, were working at the same level as their male counterparts, despite their lack of mention in the published literature which generally holds that only men worked as cryptanalysts during this period. The present research identifies that this was not the case, and that though the number of confirmed female cryptanalysts remains small and elusive, these women were nonetheless important for the role that they played. This thesis examines published work on British cryptanalysis between 1914 and 1946, demonstrating that these accounts are almost exclusively by men and about men. The research presented uses original documentation and interviews to advance and place on record knowledge about female cryptanalysts who worked in high-level codebreaking during time both of war and peace in a gendered approach. The analysis sets out the case studies of six women - four cryptanalysts, one linguist and a decoder - who typify the roles that women held in cryptanalysis between 1914 and 1946, providing an in-depth study of their backgrounds and roles they carried out for the British Admiralty’s Room 40, the War Office’s MI1(b) and HushWAACs, and the Foreign Office’s Government Code and Cypher School (GC&CS). The thesis provides a detailed historiographical chronology in a gendered approach of the women’s role in cryptanalysis from the beginnings of modern codebreaking in the First World War, through the interwar creation of GC&CS, to the vast cryptanalytical organisation at Bletchley Park during the Second World War, setting out the context of relevant literature and archival materials. Definitions are derived for key terms whose meanings have changed over the period, causing confusion and erroneous conclusions to be drawn, and key themes are identified which can be used in the identification of future female cryptanalysts. This thesis clearly identifies that women were working as high-grade cryptanalysts during the period 1914 to 1946, and offers pointers and analytical tools to potential further identifications in future research

    Looking towards the future: the changing nature of intrusive surveillance and technical attacks against high-profile targets

    Get PDF
    In this thesis a novel Bayesian model is developed that is capable of predicting the probability of a range of eavesdropping techniques deployed, given an attacker's capability, opportunity and intent. Whilst limited attention by academia has focused on the cold war activities of Soviet bloc and Western allies' bugging of embassies, even less attention has been paid to the changing nature of the technology used for these eavesdropping events. This thesis makes four contributions: through the analysis of technical eavesdropping events over the last century, technological innovation is shown to have enriched the eavesdropping opportunities for a range of capabilities. The entry barrier for effective eavesdropping is lowered, while for the well resourced eavesdropper, the requirement for close access has been replaced by remote access opportunities. A new way to consider eavesdropping methods is presented through the expert elicitation of capability and opportunity requirements for a range of present-day eavesdropping techniques. Eavesdropping technology is shown to have life-cycle stages with the technology exploited by different capabilities at different times. Three case studies illustrate that yesterday’s secretive government method becomes today’s commodity. The significance of the egress transmission path is considered too. Finally, by using the expert elicitation information derived for capability, opportunity and life-cycle position, for a range of eavesdropping techniques, it is shown that it is possible to predict the probability of particular eavesdropping techniques being deployed. This novel Bayesian inferencing model enables scenarios with incomplete, uncertain or missing detail to be considered. The model is validated against the previously collated historic eavesdropping events. The development of this concept may be scaled with additional eavesdropping techniques to form the basis of a tool for security professionals or risk managers wishing to define eavesdropping threat advice or create eavesdropping policies based on the rigour of this technological study.Open Acces

    Interception: law, media, and techniques

    Get PDF
    In 2013, Edward Snowden provided journalists with copies of classified documents detailing the operations of the National Security Agency of the United States and its allies; in particular, the UK’s Government Communications Headquarters. Snowden explained that he hoped to set the conditions for a new technical literacy that would alter understandings of the relationship between digital communications and law. This thesis asks whether or not law is capable of repaying Snowden’s faith. To that end, it offers a media-theoretical genealogy of the interception of communication in the UK. Interception is presented as an effect of different sets of technical operations, mediated and processed by communication devices and networks. The thesis traces interception techniques: from their beginnings in the General Post Office; in their evolution through the operations of technical media; to their reappearance in the operations of digital media that constitute the internet. The authorisation of interception, meanwhile, has always depended upon legal techniques mediated by interception warrants. A genealogy of the interception warrant is presented through an archival study of the distinctly different practices of document production that manufactured and programmed warrants in different media epochs; from the medieval Chancery and paper bureaucracies of state institutions to the graphical user interface, which mediates between interception techniques and law today. Finally, the thesis addresses the function of legislation as it in turn addresses warrants and interception techniques. Law and legislation, it is argued, are incapable of constraining technical operations of interception because, like interception, law is already an effect of media-technical operations. The law operates not by controlling interception, but by processing it, assigning meaning to it, and protecting the secrecy of ongoing interception operations
    corecore