The Eris hybrid cipher

An earlier paper by the same author (IACR Eprint 2008/473) suggested combining a block cipher and a stream cipher to get a strong hybrid cipher. This paper proposes a specific cipher based on those ideas, using the HC-128 stream cipher and a tweakable block cipher based on Serpent

Tight Indistinguishability Bounds for the XOR of Independent Random Permutations by Fourier Analysis

The XOR of two independent permutations (XoP) is a well-known construction for achieving security beyond the birthday bound when implementing a pseudorandom function using a block cipher (i.e., a pseudorandom permutation). The idealized construction (where the permutations are uniformly chosen and independent) and its variants have been extensively analyzed over nearly 25 years. The best-known asymptotic information-theoretic indistinguishability bound for the XoP construction is $O(q/2^{1.5n})$, derived by Eberhard in 2017, where $q$ is the number of queries and $n$ is the block length. A generalization of the XoP construction outputs the XOR of $r \geq 2$ independent permutations, and has also received significant attention in both the single-user and multi-user settings. In particular, for $r = 3$, the best-known bound (obtained by Choi et al. [ASIACRYPT\u2722]) is about $q^2/2^{2.5 n}$ in the single-user setting and $\sqrt{u} q_{\max}^2/2^{2.5 n}$ in the multi-user setting (where $u$ is the number of users and $q_{\max}$ is the number of queries per user). In this paper, we prove an indistinguishability bound of $q/2^{(r - 0.5)n}$ for the (generalized) XoP construction in the single-user setting, and a bound of $\sqrt{u} q_{\max}/2^{(r - 0.5)n}$ in the multi-user setting. In particular, for $r=2$, we obtain the bounds $q/2^{1.5n}$ and $\sqrt{u} q_{\max}/2^{1.5n}$ in single-user and multi-user settings, respectively. For $r=3$ the corresponding bounds are $q/2^{2.5n}$ and $\sqrt{u} q_{\max}/2^{2.5n}$. All of these bounds hold assuming $q < 2^{n}/2$ (or $q_{\max} < 2^{n}/2$). Compared to previous works, we improve all the best-known bounds for the (generalized) XoP construction in the multi-user setting, and the best-known bounds for the generalized XoP construction for $r \geq 3$ in the single-user setting (assuming $q \geq 2^{n/2}$). For the basic two-permutation XoP construction in the single-user setting, our concrete bound of $q/2^{1.5n}$ stands in contrast to the asymptotic bound of $O(q/2^{1.5n})$ by Eberhard. Since all of our bounds are matched (up to constant factors) for $q \geq 2^{n/2}$ by attacks published by Patarin in 2008 (and their generalizations to the multi-user setting), they are all tight. We obtain our results by Fourier analysis of Boolean functions. Most of our technical work involves bounding (sums of) Fourier coefficients of the density function associated with sampling without replacement. While the proof of Eberhard relies on similar bounds, our proof is elementary and simpler

Agri-food business: Global challenges â Innovative solutions

The rise of a western-style middle class in many successful emerging economies like China currently is inducing deep structural changes on agricultural world markets and within the global agri-food business. As a result of both higher incomes and concerns over product safety and quality the global demand for high-quality and safe food products is increasing significantly. In order to meet the new required quality, globally minimum quality standards are rising and private standards emerging. All over the world these developments cause adjustments at the enterprise, chain and market levels. At the same time, the tremendously increasing demand for renewable energy has led to the emergence of a highly promising market for biomass production. This has far-reaching consequences for resource allocation in the agri-food business, for the environment, for the poor in developing countries and for agricultural policy reforms. The challenges increase with ongoing liberalisation, globalisation and standardisation, all of which change trade patterns for agricultural and food commodities, and influence production costs and commodity prices. The objective of the IAMO Forum is to show opportunities as well as risks for all participants of the food economy in the ongoing globalisation process: for small peasants in developing countries, farmers in Europe and globally active food enterprises and retailers. The success of enterprises depends on the ability to find innovative solutions with regard to the organisation of enterprises, chains, and markets, as well as future policy design. Concerning bio-energy strategies has to be identified to combat global warming most efficiently and concurrently attenuate the competition between "tank and table" on farmland. IAMO Forum 2008, as well as this book, would not have been possible without the engagement of many people and institutions. We thank the authors of the papers, as well as the referees. Furthermore we are highly indebted to MARLIES LOHR, NADINE GIEMSA and RONNY RECKE who in an outstanding way contributed to the organisation of the Forum. This is true as well for the IAMO administration, whose work we gratefully acknowledge. Many sponsors has funded the IAMO Forum 2008. We are very grateful to the German Research Foundation (DFG), The Federal Ministry of Food, Agriculture and Consumer Production in Germany, The Ministry of Cultural Affairs of the Federal State Saxony-Anhalt, Germany and last but not least the City of Halle. Further Conference sponsors are the BIONADE Corporation, Gaensefurther Mineral Water, The Wine Growers Association of the Region Saale-Unstrut, Germany, Obsthof am SüÃen See GmbH, Monsanto Company, KWS Saat AG, Sachsen-Anhalt-Tours, Baumkuchen Salzwedel and the Hallesches Brauhaus.Agribusiness, Agricultural and Food Policy, Agricultural Finance, Community/Rural/Urban Development, Industrial Organization, Institutional and Behavioral Economics, International Development, Marketing, Political Economy,

Parallel, scalable and bandwidth-optimized computational private information retrieval

With the current increase of interest in cloud computing, the security of user data stored in remote servers has become an important concern. Hiding access patterns of clients can be crucial in particular applications such as stock market or patent databases. Private Information Retrieval (PIR) is proposed to enable a client to retrieve a file stored in a cloud server without revealing the queried file to the server. In this work, we offer improvements to BddCpir, which is a PIR protocol proposed by Lipmaa. The original BddCpir uses Binary Decision Diagrams (BDD) as the data structure, where data items are stored at the sink nodes of the tree. First of all, we offer the usage of quadratic and octal trees instead, where every non-sink node has four and eight child nodes, respectively, to reduce the depth of the tree. By adopting more shallow trees, we obtain an improved server implementation which is an order of magnitude faster than the original scheme, without changing the asymptotic complexity. Secondly, we suggest a non-trivial parallelization method that takes advantage of the shared-memory multi-core architectures to further decrease server computation latencies. Finally, we show how to scale the PIR scheme for larger database sizes with only a small overhead in bandwidth complexity, with the utilization of shared-memory many-core processors. Consequently, we show how our scheme is bandwidth-efficient in terms of the data being exchanged in a run of the CPIR protocol, in proportion to the database size

Hiding query access patterns in range queries using private information retrieval and oblivious ram

This work addresses the problem of hiding query access patterns in privacypreserving range queries while guaranteeing data and query con dentiality. We propose two methods, which are based on Private Information Retrieval (PIR) and Oblivious RAM (ORAM) techniques, respectively. For the PIR based search operation, we introduce a new scheme based on Lipmaa's computationally-private information retrieval (CPIR) method. We reduce the computation cost of CPIR by reducing the number of modular exponentiation operations, employing shallow trees and utilizing multi-exponentiation techniques. Furthermore, we improved the performance of CPIR by applying parallel algorithms. For the ORAM based method, we adapted Stefanov's Path ORAM method to the privacy-preserving range search. Our analyses show that, in terms of communication cost, CPIR provides better bandwidth usage especially in large database sizes, while in computational cost, Path ORAM based method performs better due to the negligible cost of server operations. The results imply that, despite some advantageous qualitative aspects of CPIR and its highly parallel implementation, it is still an expensive scheme in terms of computation complexity in comparison with Path ORAM for hiding query access patterns in privacy preserving range queries

Agri-food business: global challenges - innovative solutions

The rise of a western-style middle class in many successful emerging economies like China currently is inducing deep structural changes on agricultural world markets and within the global agri-food business. As a result of both higher incomes and concerns over product safety and quality the global demand for high-quality and safe food products is increasing significantly. In order to meet the new required quality, globally minimum quality standards are rising and private standards emerging. All over the world these developments cause adjustments at the enterprise, chain and market levels. At the same time, the tremendously increasing demand for renewable energy has led to the emergence of a highly promising market for biomass production. This has far-reaching consequences for resource allocation in the agri-food business, for the environment, for the poor in developing countries and for agricultural policy reforms. The challenges increase with ongoing liberalisation, globalisation and standardisation, all of which change trade patterns for agricultural and food commodities, and influence production costs and commodity prices. CONTENTS: Preface... i; On the political economy of food standards ... 1, Johan F. M. Swinnen, Thijs Vandemoortele; An analytical framework for the study of deviant behaviour in production... 11, Norbert Hirschauer, Gaetano Martino; Netchain innovations for sustainable pork supply chains in an EU Context... 22, Rannia Nijhoff-Savvaki, Jacques Trienekens, Onno Omta; Inclusion of dairy farms in supply chain in Bulgaria - Modes, efficiency, perspectives... 35, Hrabrin Bachev; The effective traceability on the example of Polish supply chain ... 47, Agnieszka Bezat, Sebastian Jarzebowski; Geographical indications in transition countries: Governance, vertical integration and territorial impact. Illustration with case studies from Serbia... 58, Marguerite Paus; Processing and marketing feasibility of underutilized fruit species of Rajasthan, India ... 70, Dheeraj Singh, Lobsang Wangshu, V. C. Prahalad; Future impact of new technologies upon food quality and health in Central Eastern European countries... 82, Lajos Zoltán Bakucs, Imre Ferto, Attila Havas; Are food industry companies interested in co-financing collective agricultural marketing?... 95, Anikó Tóth, Csaba Forgács; Farmers' reasons for engaging in bioenergy utilisation and their institutional context: A case study from Germany ... 106, Melf-Hinrich Ehlers; Degree and pattern of agro-food trade integration of South-Eastern European countries with the European Union ... 118, Štefan Bojnec, Imre Ferto; Competitiveness of cotton and wheat production and processing in Central Asia ... 133, Inna Levkovych --

Using Blockchain to support Data & Service Monetization

Two required features of a data monetization platform are query and retrieval of the metadata of the resources to be monetized. Centralized platforms rely on the maturity of traditional NoSQL database systems to support these features. These databases, for example, MongoDB allows for very efficient query and retrieval of data it stores. However, centralized platforms come with a bag of security and privacy concerns, making them not the ideal approach for a data monetization platform. On the other hand, most existing decentralized platforms are only partially decentralized. In this research, I developed Cowry, a platform for publishing metadata describing available resources (data or services), discovery of published metadata including fast search and filtering. My main contribution is a fully decentralized architecture that combines blockchain and traditional distributed database to gain additional features such as efficient query and retrieval of metadata stored on the blockchain

Augmented Learning with Errors: The Untapped Potential of the Error Term

The Learning with Errors (LWE) problem has gained a lot of attention in recent years leading to a series of new cryptographic applications. Specifically, it states that it is hard to distinguish random linear equations disguised by some small error from truly random ones. Interestingly, cryptographic primitives based on LWE often do not exploit the full potential of the error term beside of its importance for security. To this end, we introduce a novel LWE-close assumption, namely Augmented Learning with Errors (A-LWE), which allows to hide auxiliary data injected into the error term by a technique that we call message embedding. In particular, it enables existing cryptosystems to strongly increase the message throughput per ciphertext. We show that A-LWE is for certain instantiations at least as hard as the LWE problem. This inherently leads to new cryptographic constructions providing high data load encryption and customized security properties as required, for instance, in economic environments such as stock markets resp. for financial transactions. The security of those constructions basically stems from the hardness to solve the A-LWE problem. As an application we introduce (among others) the first lattice-based replayable chosen-ciphertext secure encryption scheme from A-LWE

Post-quantum blockchain for internet of things domain

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonIn the evolving realm of quantum computing, emerging advancements reveal substantial challenges and threats to existing cryptographic infrastructures, particularly impacting blockchain technologies. These are pivotal for securing the Internet of Things (IoT) ecosystems. The traditional blockchain structures, integral to myriad IoT applications, are susceptible to potential quantum computations, emphasizing an urgent need for innovations in post-quantum blockchain solutions to reinforce security in the expansive domain of IoT. This PhD thesis delves into the crucial exploration and meticulous examination of the development and implementation of post-quantum blockchain within the IoT landscape, focusing on the incorporation of advanced post-quantum cryptographic algorithms in Hyperledger Fabric, a forefront blockchain platform renowned for its versatility and robustness. The primary aim is to discern viable post-quantum cryptographic solutions capable of fortifying blockchain systems against impending quantum threats enhancing security and reliability in IoT applications. The research comprehensively evaluates various post-quantum public-key generation and digital signature algorithms, performing detailed analyses of their computational time and memory usage to identify optimal candidates. Furthermore, the thesis proposes an innovative lattice-based digital signature scheme Fast-Fourier Lattice-based Compact Signature over NTRU (Falcon), which leverages the Monte Carlo Markov Chain (MCMC) algorithm as a trapdoor sampler to augment its security attributes. The research introduces a post-quantum version of the Hyperledger Fabric blockchain that integrates post-quantum signatures. The system utilizes the Open Quantum Safe (OQS) library, rigorously tested against NIST round 3 candidates for optimal performance. The study highlights the capability to manage IoT data securely on the post-quantum Hyperledger Fabric blockchain through the Message Queue Telemetry Transport (MQTT) protocol. Such a configuration ensures safe data transfer from IoT sensors directly to the blockchain nodes, securing the processing and recording of sensor data within the node ledger. The research addresses the multifaceted challenges of quantum computing advancements and significantly contributes to establishing secure, efficient, and resilient post-quantum blockchain infrastructures tailored explicitly for the IoT domain. These findings are instrumental in elevating the security paradigms of IoT systems against quantum vulnerabilities and catalysing innovations in post-quantum cryptography and blockchain technologies. Furthermore, this thesis introduces strategies for the optimization of performance and scalability of post-quantum blockchain solutions and explores alternative, energy-efficient consensus mechanisms such as the Raft and Stellar Consensus Protocol (SCP), providing sustainable alternatives to the conventional Proof-of-Work (PoW) approach. A critical insight emphasized throughout this thesis is the imperative of synergistic collaboration among academia, industry, and regulatory bodies. This collaboration is pivotal to expedite the adoption and standardization of post-quantum blockchain solutions, fostering the development of interoperable and standardized technologies enriched with robust security and privacy frameworks for end users. In conclusion, this thesis furnishes profound insights and substantial contributions to implementing post-quantum blockchain in the IoT domain. It delineates original contributions to the knowledge and practices in the field, offering practical solutions and advancing the state-of-the-art in post-quantum cryptography and blockchain research, thereby paving the way for a secure and resilient future for interconnected IoT systems

The Bookish Turn: Assessing the Impact of the Book-Roll on Authorial Self- Representation in Early Hellenistic Poetry

My thesis takes its start from the oft-used description of Hellenistic poetry as ‘bookish’, but looks beyond the connotations of this label as denoting a milieu which was self-consciously intellectual, and instead considers the more fundamental ramifications of the designation: that Hellenistic poetry was bookish in its form, as much as in outlook. To consider the implications of this, I focus upon a period, and a significant poetic topos, wherein the effects of the book-roll can be most keenly discerned, assessing the impact of the medium upon authorial self- representations - particularly in the construction of authorial personae - undertaken in early Hellenistic poetry (c.323-246 BC). In Part I of the thesis, I assess the evolution of authorial self-representation in epigram, charting developments from the inscribed form of the genre through to the book-epigram collections of the Hellenistic period: I argue that the author acquired a newfound prominence in this medial transition, asserting their presence as a voice within the text as opposed to a figure situated strictly in antecedence to it. I demonstrate this through analyses of Posidippus, Callimachus, Nossis, Asclepiades, and the epigrams ascribed to Erinna, and suggest that we repeatedly observe authors undertaking composite processes of self-representation, as a direct result of the composite context of the book-roll. In Part II of the thesis, I examine the Mimiambs of Herodas. Through the analysis of Mimiamb 8 (in which Herodas constructs an authorial persona, and defines his poetic programme) in conjunction with an appraisal of the metapoetic dimension of the other Mimiambs, I assess the manner in which Herodas undertakes a complex, intertextual process of self-representation. Arguing that the author reflects upon the generic and medial innovations of his poetic practice across his corpus, I demonstrate that this process of reflection complements Herodas’ overt authorial self-representation in Mimiamb 8. In summary, I argue that the impact of the book-roll on authorial self-representation was wide- ranging, but that the most significant consequence of the medium was the evolution of authorial self-representation as a composite, roll-spanning activity