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Cryptography is the study and practice of techniques used to secure communications between parties and avoid being looked upon by third party. Generally speaking, cryptography constructs and analyzes protocols that prevent any third party of having access to private data that might concern individuals or government bodies, and it is applied to information security to ensure data confidentiality, data integrity, authentication and non-repudiation. Modern cryptography relies heavily on advanced mathematics, computer science, physics, electrical engineering, and communications science.

Cryptography is a key element in establishing trust and enabling services in the digital world. It is represented in a ways that are not accessible to human users. Hence, humans are left out the trust and security in the digital world. Cryptography is necessary in modern communication protocols and to many digital services. A primitive or protocol should be defined to reach the security goal. Beside the introduction part this paper represents the types of cryptography, algorithm of cryptography and techniques of cryptography and the interaction between Government and cryptography.

Encryption's new normal is changing the way in which states assert their sovereignty at home and abroad. Cryptography has gone mainstream. Now more than ever, encryption is used by ordinary citizens, often without their knowledge, and is a subject of national debate. Intelligence and law-enforcement officials warn of the dangers of messages they cannot read. Presidents and prime ministers weigh in on the way cryptography shapes the balance between liberty and security. The Edward Snowden revelations drive encryption-related coverage in major newspapers, even as the technology is rolled out by increasing numbers of companies over government objections. All told, it may be the most international attention a mathematical concept has received since the space race. These ongoing debates exist at the intersection of at least three fields: law, applied mathematics and international relations. The legal debate varies by country, and centres on what restrictions on cryptography the government may enact under each state's domestic political system. The debate in applied maths, drawing on computer science and software engineering, addresses whether or not it is technically feasible to place limitations on cryptographic implementations, such as those desired by some governments, without sacrificing security or the right to privacy. The international-relations debate, which is only nascent, questions what the widespread use of cryptography means for the future of states in the international system. For all the recent discussion and increasing use of cryptography, however, many of the core concepts of the modern debate are not entirely new. In legal and applied-maths circles, similar debates took place in the 1980s, as powerful new forms of encryption came to the fore. Another round of discussion took place in the 1990s, as the spread of the internet dramatically increased the number of encryption users and raised the prospect that the security and privacy offered by cryptography would spread beyond American borders. Much can be learned from these previous debates that can help to ascertain the implications of cryptography for international relations. In several important respects, the increasing implementation of secure cryptographic systems reshapes the concept of state sovereignty. It is clear that the seemingly irreversible rise of strong encryption will place particular types of communication beyond the state's reach, while at the same time leaving policymakers with alternative means of reasserting state power. In this way, encryption is similar to other potential challenges to sovereignty, such as globalisation. In practice, the widespread use of cryptography alters how states relate to one another, and to their own citizens. It raises important questions about the legitimate use of a state's own power, and the ways in which this power is constrained by the power of other states. (Survival / SWP)

Association Security and Cryptography is a plan to guarantee association and data transmission over far off association. Data Security is the central piece of secure data transmission over sensitive association. Association security remembers the endorsement of permission to data for an association, which is obliged by the association executive. Customers pick or are consigned an ID and mystery state or other affirming information that grants them induction to information and ventures inside their capacity. Association security covers an arrangement of PC associations, both public and private, that are used in customary positions driving trades and exchanges among associations, government workplaces and individuals. Associations can be private, for instance, inside an association, and others which might be accessible to network. Association security is locked in with affiliations, adventures, and various kinds of establishments. Aggravation receptive association (DTN) progressions are getting victorious plans that award center points to talk with each other in these absurd frameworks organization conditions. Consistently, when there is no restriction to-end relationship between a source and a goal pair, the messages from the source center point may require keeping things under control in the center points for a lot of time impending the affiliation would be in the end set up. The possibility of value based encryption (ABE) is a capable technique that fulfills the requirements for secure data recuperation in DTNs. Especially, Cipher text-Policy ABE (CP-ABE) gives a versatile technique for encoding data with the ultimate objective that the scramble or portrays the property set that the unscramble or needs to need to translate the code text. Thusly, divergent customers are allowable to unscramble different pieces of data per the security system.

Backdooring cryptographic algorithms is an indisputable taboo in the cryptographic literature for a good reason: however noble the intentions, backdoors might fall in the wrong hands, in which case security is completely compromised. Nonetheless, more and more legislative pressure is being produced to enforce the use of such backdoors. In this work we introduce the concept of disposable cryptographic backdoors which can be used only once and become useless after that. These exotic primitives are impossible in the classical digital world without stateful and secure trusted hardware support, but, as we show, are feasible assuming quantum computation and access to classical stateless hardware tokens. Concretely, we construct a disposable (single-use) version of message authentication codes, and use them to derive a black-box construction of stateful hardware tokens in the above setting with quantum computation and classical stateless hardware tokens. This can be viewed as a generic transformation from stateful to stateless tokens and enables, among other things, one-time programs and memories. This is to our knowledge the first provably secure construction of such primitives from stateless tokens. As an application of disposable cryptographic backdoors we use our constructed primitive above to propose a middle-ground solution to the recent legislative push to backdoor cryptography: the conflict between Apple and FBI. We show that it is possible for Apple to create a one-time backdoor which unlocks any single device, and not even Apple can use it to unlock more than one, i.e., the backdoor becomes useless after it is used. We further describe how to use our ideas to derive a version of CCA-secure public key encryption, which is accompanied with a disposable (i.e., single-use, as in the above scenario) backdoor.

Durch die zunehmende Digitalisierung, und insbesondere dem sogenannten "Internet of Things", ist der Bedarf an zuverlässigen kryptografischen Verfahren nicht nur für Behörden, sondern auch für Privatpersonen wichtig geworden. In den letzten Jahrzehnten wurde eine Vielzahl an unterschiedlichsten Lösungen präsentiert. Diese Arbeit befasst sich mit elliptischen Kurven und kryptographischen Verfahren, deren Sicherheit auf dem "Elliptic Curve Discrete Logarithm Problem" beruht. Zunächst wird ein grober Überblick über die erforderlichen algebraischen Konzepte, den projektiven Raum und grundlegende Begriffe und Konzepte aus der Kryptographie gegeben. Im Folgenden werden elliptische Kurven als projektive ebene Kurven eingeführt, welche durch ein nichtsinguläres Weierstraß-Polynom definiert sind. Eigenschaften der Schnittpunkte von (elliptischen) Kurven und projektiven Geraden werden herausgearbeitet und ein Spezialfall des Satzes von Bézout wird bewiesen. Dadurch kann im Anschluss gezeigt werden, dass durch wiederholtes Schneiden von Geraden mit einer elliptischen Kurve ein Gruppengesetz für die Menge der Schnittpunkte aufgestellt werden kann. Es werden explizite Formeln für die "Punktaddition" hergeleitet. Danach werden kryptographische Verfahren vorgestellt, die eben diese Gruppe nutzen. Abschließend wird ein Ausblick in die Zukunft der "Elliptic Curve Cryptography" gegeben. ; The increasing digitization, and in particular the Internet of Things, has made the need for reliable cryptographic processes important not only for government use but also for private individuals. Over the last decades, many different solutions have been proposed. This thesis deals with elliptic curves and cryptographic schemes whose security rely on the "Elliptic Curve Discrete Logarithm Problem". First, a rough overview of the required algebraic concepts, projective space, and basic terms and concepts from cryptography is given. In the following, elliptic curves are introduced as projective plane curves defined by a non-singular Weierstraß polynomial. The properties of the intersection of (elliptic) curves and projective lines are worked out, and a special case of Bézout's theorem is proved. By repeatedly intersecting lines with an elliptic curve, a group law can be established on the set of intersection points. Explicit formulas for performing "point addition" are derived. Subsequently, cryptographic schemes making use of the elliptic curve group are presented. Finally, an outlook into the future of "Elliptic Curve Cryptography" is given. ; Arbeit an der Bibliothek noch nicht eingelangt - Daten nicht geprüft ; Abweichender Titel laut Übersetzung des Verfassers/der Verfasserin ; Karl-Franzens-Universität Graz, Diplomarbeit, 2021 ; (VLID)6525764

Elliptic Curve Cryptography (ECC) is a branch of public-key cryptography based on the arithmetic of elliptic curves. In the short life of ECC, most standards have proposed curves defined over prime finite fields using the short Weierstrass form. However, some researchers have started to propose as a more secure alternative the use of Edwards and Montgomery elliptic curves, which could have an impact in current ECC deployments. This chapter presents the different types of elliptic curves used in Cryptography together with the best-known procedure for generating secure elliptic curves, Brainpool. The contribution is completed with the examination of the latest proposals regarding secure elliptic curves analyzed by the SafeCurves initiative. ; Acknowledgements: This work has been partly supported by Ministerio de Economía y Competitividad (Spain) under the project TIN2014-55325-C2-1-R (ProCriCiS), and by Comunidad de Madrid (Spain) under the project S2013/ICE-3095-CM (CIBERDINE), cofinanced with the European Union FEDER funds.

I recently caught up with an activist friend I've known for twenty-five years. We got into this stuff at the tail end of what were then called the crypto wars, a set of legal and policy battles to free strong encryption from the US and UK's security services and allow it to be used to […]

In 2011, we are entering a decade where Radio Frequency IDentification (RFID) systems will become ubiquitous, slowly but surely replacing its old ancestor: the barcode. With the RFID technology come many advantages such as faster retailing, continuous control along the supply chain, real-time monitoring and localization of items, etc. However, all these benefits come to the condition of secure systems, especially in sensitive application areas such as military, finance, pharmaceutics, etc. Additionally, the privacy aspect involved with this technology could become a major issue in the perspective of a global adoption. In the past few years, an increasing number of researchers concentrates their efforts into providing secure solutions for RFID systems. After several attempts to integrate traditional cryptographic primitives into small, embedded, and extremely resource constrained devices, the results were mostly unsatisfactory. As a conclusion, a new branch of cryptography, commonly called Lightweight Cryptography, emerged to address the issues of these tiny ubiquitous devices. This Thesis presents a comprehensive engineering to lightweight cryptography, proposes a classification and explores its various ramifications by giving key examples in each of them. We select two of these branches, ultralightweight cryptography and symmetric-key cryptography, and propose a cryptographic primitive in each of them. In the case of symmetric-key cryptography, we propose a stream cipher that has a footprint among the smallest in the published literature and aims at being implemented on printed electronics RFID tags. Then, we compare different cryptographic primitives based on their key parameters: throughput, area, power consumption and level of security. Our main concern is the integrability of these selected primitives into real passive RFID tags. Therefore, in order to go beyond a comparison of the different parameters, we propose a metric that combines all their characteristics into one single value. This metric also has the advantage of being customizable, depending on the requirement of an integrator for a particular application. Finally, we conclude that the research for finding robust cryptographic primitive in the branch of lightweight cryptography still has some nice days ahead, and that providing a secure cryptosystem for printed electronics RFID tags remains an open research topic.