Everlasting Secrecy by Exploiting Eavesdropper\u27s Receiver Non-Idealities

This dissertation focuses on secrecy, which is a primary concern in modern communication. Secrecy has traditionally been obtained by cryptography, which is based on assumptions on current and future computational capabilities of the eavesdropper. However, there are numerous examples of cryptographic schemes being broken that were supposedly secure, often when the signal was recorded by the adversary for later processing. This motivates seeking types of secrecy that are provably everlasting for sensitive applications. The desire for such everlasting security suggests considering information-theoretic approaches, where the eavesdropper cannot extract any information about the secret message from the received signal. However, since the location and channel state information of a passive eavesdropper is generally unknown, it is challenging to know whether the advantage required to achieve information-theoretic security for a given scenario is provided, and thus attempting to obtain information-theoretic security via commonly-envisioned approaches leads to a significant risk in wireless communication. In this dissertation, we present a new perspective on how to generate the necessary information-theoretic advantage required for secret communication in the wireless environment. The proposed technique does not rely on the channel between the transmitter and the eavesdropper\u27s receiver because we exploit receiver\u27s processing effects for security. In particular, we attack the eavesdropper\u27s analog-to-digital (A/D) converter to generate the advantage required to obtain information-theoretic secrecy, as follows. Based on a key pre-shared between the legitimate nodes that only needs to be kept secret during transmission (and we pessimistically assume it will be handed to the adversary immediately afterward) we insert intentional distortion on the transmitted signal. Since the intended recipient of the signal knows the key and hence the distortion, it can undo the distortion before his/her A/D, whereas the eavesdropper must store the signal in memory and try to compensate for the distortion after the A/D conversion. Since the A/D is necessarily a non-linear component of the receiver, the operations are not necessarily commutative and there is the potential for information-theoretic security. This dissertation studies two practical instantiations of this approach to obtain everlasting secrecy against eavesdroppers with different hardware capabilities. As a first step, the transmitted signal is modulated by two vastly different power levels at the transmitter based on the key. Since the intended recipient knows the key, he/she can undo the power modulation before the A/D, putting the signal in the appropriate range for analog-to-digital conversion. The eavesdropper, on the other hand, must compromise between larger quantization noise and more A/D overflows, and thus will lose information required to recover the message. Hence, information-theoretic security is obtained. We show that this method can provide information-theoretic secrecy even when the eavesdropper has perfect access to the output of the transmitter, and even when the eavesdropper has an A/D that has better quality than the legitimate receiver\u27s A/D. A risk of the power modulation approach is a sophisticated eavesdropper with multiple A/Ds. In our second approach, in order to attack such an eavesdropper, we introduce the idea of adding random jamming (based on the ephemeral key) to the signal. In this case the intended recipient can simply subtract off the jamming signal and its signal will be well-matched to the span of its A/D converter, while the eavesdropper has difficulty because it does not know the key during transmission: if it does not change the span of the A/D, it will lose information due to A/D overflows, and, if it enlarges the span of the A/D to cover all possible received signal values, the width of each quantization level will be increased, and thus the eavesdropper will lose information due to high quantization noise. Hence, the desired advantage for information-theoretic secrecy is obtained. Finally, we study the combination of random jamming and frequency hopping in wideband channels, and show that considering the current fundamental limits of analog-to-digital conversion, this method can provide everlasting secrecy in wireless environments against any eavesdropper

Analog Cancellation of a Known Remote Interference: Hardware Realization and Analysis

The onset of quantum computing threatens commonly used schemes for information secrecy across wireless communication channels, particularly key-based data-level encryption. This calls for secrecy schemes that can provide everlasting secrecy resistant to increased computational power of an adversary. One novel physical layer scheme proposes that an intended receiver capable of performing analog cancellation of a known key-based interference would hold a significant advantage in recovering small underlying messages versus an eavesdropper performing cancellation after analog-to-digital conversion. This advantage holds even in the event that an eavesdropper can recover and use the original key in their digital cancellation. Inspired by this scheme, a flexible software-defined radio receiver design capable of maintaining analog cancellation ratios consistently over 40 dB, reaching up to and over 50 dB, is implemented in this thesis. Maintaining this analog cancellation requires very precise time-frequency synchronization along with accurate modeling and simulation of the channel effects on the interference. The key sources of synchronization error preventing this test bed from achieving and maintaining perfect interference cancellation, sub-sample period timing errors and limited radio frequency stability, are explored for possible improvements. To further prove robustness of the implemented secrecy scheme, the testbed is shown to operate with both phase-shift keying and frequency-modulated waveforms. Differences in the synchronization algorithm used for the two waveforms are highlighted. Interference cancellation performance is measured for increasing interference bandwidth and shown to decrease with such. The implications this testbed has on security approaches based on intentional interference employed to confuse eavesdroppers is approached from the framework proposed in the motivating everlasting secrecy scheme. Using analog cancellation levels from the hardware testbed, it is calculated that secrecy rates up to 2.3 bits/symbol are gained by receivers (intended or not) performing interference cancellation in analog rather than on a digital signal processor. Inspired by the positive gains in secrecy over systems not performing analog cancellation prior to signal reception, a novel secrecy scheme that focuses on the advantage an analog canceller holds in receiver amplifier compression is proposed here. The adversary amplifier is assumed to perform linear cancellation after the interference has passed through their nonlinear amplifier. This is accomplished by deriving the distribution of the interference residual after undergoing an inverse tangent transfer function and perfect linear cancellation. Parameters of this scheme are fit for the radios and cancellation ratios observed in the testbed, resulting in a secrecy gain of 0.95 bits/symbol. The model shows that larger message powers can still be kept secure for the achieved levels of cancellation, thus providing an even greater secrecy gain with increased message transmission power

Data protection and transborder data flows : implications for Nigeria's integration into the global network economy

One of the realities that developing countries like Nigeria have to face today is that national and international markets have become more and more interconnected through the global platform of telecommunications and the Internet. This global networked economy is creating a paradigm shift in the focus of development goals and strategies particularly for developing countries. Globalisation is driving the nations of the world more into political and economic integration. These integrations are enhanced by a globally interconnected network of economic and communication systems at the apex of which is the Internet. This network of networks thrives on and encourages the expansion of cross-border flows of ideas and information, goods and services, technology and capital. Being an active member of the global network economy is essential to Nigeria’s economic development. It must plug into the network or risk being shut out. The global market network operates by means of rules and standards that are largely set by the dominant players in the network. Data protection is a critical component of the regime of rules and standards that govern the global network economy; it is evolving into an international legal order that transcends geographical boundaries. The EU Directive on data protection is the de facto global standard for data protection; it threatens to exclude non-EU countries without an adequate level of privacy protection from the EU market. More than 50 countries have enacted data protection laws modelled on the EU standard. Access to the huge EU market is a major motivation for the current trend in global harmonisation of domestic data protection laws. This trend provides a compelling reason for examining the issues relating to data protection and trans-border data flows and their implications for Nigeria’s desire to integrate into the global network economy. There are two primary motivations for legislating restrictions on the flow of data across national boundaries. The first is the concern for the privacy of the citizens, and second, securing the economic well-being of a nation. It is important that Nigeria’s privacy protection keeps pace with international norms in the provision of adequate protection for information privacy order to prevent potential impediments to international trading opportunities.Public, Constitutional, and InternationalLL. D

Tematski zbornik radova međunarodnog značaja. Tom 3 / Međunarodni naučni skup “Dani Arčibalda Rajsa”, Beograd, 10-11. mart 2016.

In front of you is the Thematic Collection of Papers presented at the International Scientific Conference “Archibald Reiss Days”, which was organized by the Academy of Criminalistic and Police Studies in Belgrade, in co-operation with the Ministry of Interior and the Ministry of Education, Science and Technological Development of the Republic of Serbia, National Police University of China, Lviv State University of Internal Affairs, Volgograd Academy of the Russian Internal Affairs Ministry, Faculty of Security in Skopje, Faculty of Criminal Justice and Security in Ljubljana, Police Academy “Alexandru Ioan Cuza“ in Bucharest, Academy of Police Force in Bratislava and Police College in Banjaluka, and held at the Academy of Criminalistic and Police Studies, on 10 and 11 March 2016. The International Scientific Conference “Archibald Reiss Days” is organized for the sixth time in a row, in memory of the founder and director of the first modern higher police school in Serbia, Rodolphe Archibald Reiss, PhD, after whom the Conference was named. The Thematic Collection of Papers contains 165 papers written by eminent scholars in the field of law, security, criminalistics, police studies, forensics, informatics, as well as by members of national security system participating in education of the police, army and other security services from Belarus, Bosnia and Herzegovina, Bulgaria, China, Croatia, Greece, Hungary, Macedonia, Montenegro, Romania, Russian Federation, Serbia, Slovakia, Slovenia, Spain, Switzerland, Turkey, Ukraine and United Kingdom. Each paper has been double-blind peer reviewed by two reviewers, international experts competent for the field to which the paper is related, and the Thematic Conference Proceedings in whole has been reviewed by five competent international reviewers. The papers published in the Thematic Collection of Papers contain the overview of contemporary trends in the development of police education system, development of the police and contemporary security, criminalistic and forensic concepts. Furthermore, they provide us with the analysis of the rule of law activities in crime suppression, situation and trends in the above-mentioned fields, as well as suggestions on how to systematically deal with these issues. The Collection of Papers represents a significant contribution to the existing fund of scientific and expert knowledge in the field of criminalistic, security, penal and legal theory and practice. Publication of this Collection contributes to improving of mutual cooperation betw

Bowdoin Orient v.134, no.1-24 (2004-2005)

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