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Book Cryptography for Payment Professionals

Download or read book Cryptography for Payment Professionals written by Ilya Dubinsky and published by CRC Press. This book was released on 2023-05-10 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although cryptography plays an essential part in most modern solutions, especially in payments, cryptographic algorithms remain a black box for most users of these tools. Just as a sane backend developer does not drill down into low-level disk access details of a server filesystem, payments professionals have enough things to worry about before they ever need to bother themselves with debugging an encrypted value or a message digest. However, at a certain point, an engineer faces the need to identify a problem with a particular algorithm or, perhaps, to create a testing tool that would simulate a counterpart in a protocol that involves encryption. The world of cryptography has moved on with giant leaps. Available technical standards mention acronyms and link to more standards, some of which are very large while others are not available for free. After finding the standards for the algorithm, the specific mode of operation must also be identified. Most implementations use several cryptographic primitives—for example, key derivation with a block cipher, which produces a secret that is used together with a hash function and a double padding scheme to produce a digital signature of a base64-encoded value. Understanding this requires more sifting through online sources, more reading of platform and library documents, and finally, when some code can be written, there are very few test cases to validate it. Cryptography for Payment Professionals is intended for technical people, preferably with some background in software engineering, who may need to deal with a cryptographic algorithm in the payments realm. It does not cover the payment technology in-depth, nor does it provide more than a brief overview of some regulations and security standards. Instead, it focuses on the cryptographic aspects of each field it mentions. Highlights include: Major cryptographic algorithms and the principles of their operation Cryptographic aspects of card-present (e.g., magnetic stripe, EMV) and online (e.g., e-Commerce and 3DS 2.0) transactions A detailed description of TDES DUKPT and AES DUKPT protocols, as well as an example implementation and test cases for both It is best if the reader understands programming, number and string representations in machine memory, and bit operations. Knowledge of C, Python, or Java may make the examples easier to read but this is not mandatory. Code related to the book is available at the author’s GitHub site: https://github.com/ilya-dubinsky/cfpp

Book Cryptography for Payment Professionals

Download or read book Cryptography for Payment Professionals written by Ilya Dubinsky and published by CRC Press. This book was released on 2023-05-10 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although cryptography plays an essential part in most modern solutions, especially in payments, cryptographic algorithms remain a black box for most users of these tools. Just as a sane backend developer does not drill down into low-level disk access details of a server filesystem, payments professionals have enough things to worry about before they ever need to bother themselves with debugging an encrypted value or a message digest. However, at a certain point, an engineer faces the need to identify a problem with a particular algorithm or, perhaps, to create a testing tool that would simulate a counterpart in a protocol that involves encryption. The world of cryptography has moved on with giant leaps. Available technical standards mention acronyms and link to more standards, some of which are very large while others are not available for free. After finding the standards for the algorithm, the specific mode of operation must also be identified. Most implementations use several cryptographic primitives—for example, key derivation with a block cipher, which produces a secret that is used together with a hash function and a double padding scheme to produce a digital signature of a base64-encoded value. Understanding this requires more sifting through online sources, more reading of platform and library documents, and finally, when some code can be written, there are very few test cases to validate it. Cryptography for Payment Professionals is intended for technical people, preferably with some background in software engineering, who may need to deal with a cryptographic algorithm in the payments realm. It does not cover the payment technology in-depth, nor does it provide more than a brief overview of some regulations and security standards. Instead, it focuses on the cryptographic aspects of each field it mentions. Highlights include: Major cryptographic algorithms and the principles of their operation Cryptographic aspects of card-present (e.g., magnetic stripe, EMV) and online (e.g., e-Commerce and 3DS 2.0) transactions A detailed description of TDES DUKPT and AES DUKPT protocols, as well as an example implementation and test cases for both It is best if the reader understands programming, number and string representations in machine memory, and bit operations. Knowledge of C, Python, or Java may make the examples easier to read but this is not mandatory. Code related to the book is available at the author’s GitHub site: https://github.com/ilya-dubinsky/cfpp

Book Modern Cryptography for Cybersecurity Professionals

Download or read book Modern Cryptography for Cybersecurity Professionals written by Lisa Bock and published by Packt Publishing Ltd. This book was released on 2021-06-11 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: As a cybersecurity professional, discover how to implement cryptographic techniques to help your organization mitigate the risks of altered, disclosed, or stolen data Key FeaturesDiscover how cryptography is used to secure data in motion as well as at restCompare symmetric with asymmetric encryption and learn how a hash is usedGet to grips with different types of cryptographic solutions along with common applicationsBook Description In today's world, it is important to have confidence in your data storage and transmission strategy. Cryptography can provide you with this confidentiality, integrity, authentication, and non-repudiation. But are you aware of just what exactly is involved in using cryptographic techniques? Modern Cryptography for Cybersecurity Professionals helps you to gain a better understanding of the cryptographic elements necessary to secure your data. The book begins by helping you to understand why we need to secure data and how encryption can provide protection, whether it be in motion or at rest. You'll then delve into symmetric and asymmetric encryption and discover how a hash is used. As you advance, you'll see how the public key infrastructure (PKI) and certificates build trust between parties, so that we can confidently encrypt and exchange data. Finally, you'll explore the practical applications of cryptographic techniques, including passwords, email, and blockchain technology, along with securely transmitting data using a virtual private network (VPN). By the end of this cryptography book, you'll have gained a solid understanding of cryptographic techniques and terms, learned how symmetric and asymmetric encryption and hashed are used, and recognized the importance of key management and the PKI. What you will learnUnderstand how network attacks can compromise dataReview practical uses of cryptography over timeCompare how symmetric and asymmetric encryption workExplore how a hash can ensure data integrity and authenticationUnderstand the laws that govern the need to secure dataDiscover the practical applications of cryptographic techniquesFind out how the PKI enables trustGet to grips with how data can be secured using a VPNWho this book is for This book is for IT managers, security professionals, students, teachers, and anyone looking to learn more about cryptography and understand why it is important in an organization as part of an overall security framework. A basic understanding of encryption and general networking terms and concepts is needed to get the most out of this book.

Book Fundamentals of Cryptology

    Book Details:
  • Author : Henk C.A. van Tilborg
  • Publisher : Springer Science & Business Media
  • Release : 2006-04-18
  • ISBN : 0306470535
  • Pages : 496 pages

Download or read book Fundamentals of Cryptology written by Henk C.A. van Tilborg and published by Springer Science & Business Media. This book was released on 2006-04-18 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: The protection of sensitive information against unauthorized access or fraudulent changes has been of prime concern throughout the centuries. Modern communication techniques, using computers connected through networks, make all data even more vulnerable for these threats. Also, new issues have come up that were not relevant before, e. g. how to add a (digital) signature to an electronic document in such a way that the signer can not deny later on that the document was signed by him/her. Cryptology addresses the above issues. It is at the foundation of all information security. The techniques employed to this end have become increasingly mathematical of nature. This book serves as an introduction to modern cryptographic methods. After a brief survey of classical cryptosystems, it concentrates on three main areas. First of all, stream ciphers and block ciphers are discussed. These systems have extremely fast implementations, but sender and receiver have to share a secret key. Public key cryptosystems (the second main area) make it possible to protect data without a prearranged key. Their security is based on intractable mathematical problems, like the factorization of large numbers. The remaining chapters cover a variety of topics, such as zero-knowledge proofs, secret sharing schemes and authentication codes. Two appendices explain all mathematical prerequisites in great detail. One is on elementary number theory (Euclid's Algorithm, the Chinese Remainder Theorem, quadratic residues, inversion formulas, and continued fractions). The other appendix gives a thorough introduction to finite fields and their algebraic structure.

Book Guide to Elliptic Curve Cryptography

Download or read book Guide to Elliptic Curve Cryptography written by Darrel Hankerson and published by Springer Science & Business Media. This book was released on 2006-06-01 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: After two decades of research and development, elliptic curve cryptography now has widespread exposure and acceptance. Industry, banking, and government standards are in place to facilitate extensive deployment of this efficient public-key mechanism. Anchored by a comprehensive treatment of the practical aspects of elliptic curve cryptography (ECC), this guide explains the basic mathematics, describes state-of-the-art implementation methods, and presents standardized protocols for public-key encryption, digital signatures, and key establishment. In addition, the book addresses some issues that arise in software and hardware implementation, as well as side-channel attacks and countermeasures. Readers receive the theoretical fundamentals as an underpinning for a wealth of practical and accessible knowledge about efficient application. Features & Benefits: * Breadth of coverage and unified, integrated approach to elliptic curve cryptosystems * Describes important industry and government protocols, such as the FIPS 186-2 standard from the U.S. National Institute for Standards and Technology * Provides full exposition on techniques for efficiently implementing finite-field and elliptic curve arithmetic * Distills complex mathematics and algorithms for easy understanding * Includes useful literature references, a list of algorithms, and appendices on sample parameters, ECC standards, and software tools This comprehensive, highly focused reference is a useful and indispensable resource for practitioners, professionals, or researchers in computer science, computer engineering, network design, and network data security.

Book Encyclopedia of Cryptography and Security

Download or read book Encyclopedia of Cryptography and Security written by Henk C.A. van Tilborg and published by Springer Science & Business Media. This book was released on 2014-07-08 with total page 1457 pages. Available in PDF, EPUB and Kindle. Book excerpt: Expanded into two volumes, the Second Edition of Springer’s Encyclopedia of Cryptography and Security brings the latest and most comprehensive coverage of the topic: Definitive information on cryptography and information security from highly regarded researchers Effective tool for professionals in many fields and researchers of all levels Extensive resource with more than 700 contributions in Second Edition 5643 references, more than twice the number of references that appear in the First Edition With over 300 new entries, appearing in an A-Z format, the Encyclopedia of Cryptography and Security provides easy, intuitive access to information on all aspects of cryptography and security. As a critical enhancement to the First Edition’s base of 464 entries, the information in the Encyclopedia is relevant for researchers and professionals alike. Topics for this comprehensive reference were elected, written, and peer-reviewed by a pool of distinguished researchers in the field. The Second Edition’s editorial board now includes 34 scholars, which was expanded from 18 members in the First Edition. Representing the work of researchers from over 30 countries, the Encyclopedia is broad in scope, covering everything from authentication and identification to quantum cryptography and web security. The text’s practical style is instructional, yet fosters investigation. Each area presents concepts, designs, and specific implementations. The highly-structured essays in this work include synonyms, a definition and discussion of the topic, bibliographies, and links to related literature. Extensive cross-references to other entries within the Encyclopedia support efficient, user-friendly searches for immediate access to relevant information. Key concepts presented in the Encyclopedia of Cryptography and Security include: Authentication and identification; Block ciphers and stream ciphers; Computational issues; Copy protection; Cryptanalysis and security; Cryptographic protocols; Electronic payment and digital certificates; Elliptic curve cryptography; Factorization algorithms and primality tests; Hash functions and MACs; Historical systems; Identity-based cryptography; Implementation aspects for smart cards and standards; Key management; Multiparty computations like voting schemes; Public key cryptography; Quantum cryptography; Secret sharing schemes; Sequences; Web Security. Topics covered: Data Structures, Cryptography and Information Theory; Data Encryption; Coding and Information Theory; Appl.Mathematics/Computational Methods of Engineering; Applications of Mathematics; Complexity. This authoritative reference will be published in two formats: print and online. The online edition features hyperlinks to cross-references, in addition to significant research.

Book Cryptography and Data Security

Download or read book Cryptography and Data Security written by Dorothy Elizabeth Robling Denning and published by Addison Wesley Publishing Company. This book was released on 1982 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt: Encryption algorithms. Cryptographic technique. Access controls. Information controls. Inference controls.

Book Applied Cryptography

    Book Details:
  • Author : Bruce Schneier
  • Publisher : John Wiley & Sons
  • Release : 2017-05-25
  • ISBN : 1119439027
  • Pages : 937 pages

Download or read book Applied Cryptography written by Bruce Schneier and published by John Wiley & Sons. This book was released on 2017-05-25 with total page 937 pages. Available in PDF, EPUB and Kindle. Book excerpt: From the world's most renowned security technologist, Bruce Schneier, this 20th Anniversary Edition is the most definitive reference on cryptography ever published and is the seminal work on cryptography. Cryptographic techniques have applications far beyond the obvious uses of encoding and decoding information. For developers who need to know about capabilities, such as digital signatures, that depend on cryptographic techniques, there's no better overview than Applied Cryptography, the definitive book on the subject. Bruce Schneier covers general classes of cryptographic protocols and then specific techniques, detailing the inner workings of real-world cryptographic algorithms including the Data Encryption Standard and RSA public-key cryptosystems. The book includes source-code listings and extensive advice on the practical aspects of cryptography implementation, such as the importance of generating truly random numbers and of keeping keys secure. ". . .the best introduction to cryptography I've ever seen. . . .The book the National Security Agency wanted never to be published. . . ." -Wired Magazine ". . .monumental . . . fascinating . . . comprehensive . . . the definitive work on cryptography for computer programmers . . ." -Dr. Dobb's Journal ". . .easily ranks as one of the most authoritative in its field." -PC Magazine The book details how programmers and electronic communications professionals can use cryptography-the technique of enciphering and deciphering messages-to maintain the privacy of computer data. It describes dozens of cryptography algorithms, gives practical advice on how to implement them into cryptographic software, and shows how they can be used to solve security problems. The book shows programmers who design computer applications, networks, and storage systems how they can build security into their software and systems. With a new Introduction by the author, this premium edition will be a keepsake for all those committed to computer and cyber security.

Book Understanding Cryptography

    Book Details:
  • Author : Christof Paar
  • Publisher : Springer Science & Business Media
  • Release : 2009-11-27
  • ISBN : 3642041019
  • Pages : 382 pages

Download or read book Understanding Cryptography written by Christof Paar and published by Springer Science & Business Media. This book was released on 2009-11-27 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cryptography is now ubiquitous – moving beyond the traditional environments, such as government communications and banking systems, we see cryptographic techniques realized in Web browsers, e-mail programs, cell phones, manufacturing systems, embedded software, smart buildings, cars, and even medical implants. Today's designers need a comprehensive understanding of applied cryptography. After an introduction to cryptography and data security, the authors explain the main techniques in modern cryptography, with chapters addressing stream ciphers, the Data Encryption Standard (DES) and 3DES, the Advanced Encryption Standard (AES), block ciphers, the RSA cryptosystem, public-key cryptosystems based on the discrete logarithm problem, elliptic-curve cryptography (ECC), digital signatures, hash functions, Message Authentication Codes (MACs), and methods for key establishment, including certificates and public-key infrastructure (PKI). Throughout the book, the authors focus on communicating the essentials and keeping the mathematics to a minimum, and they move quickly from explaining the foundations to describing practical implementations, including recent topics such as lightweight ciphers for RFIDs and mobile devices, and current key-length recommendations. The authors have considerable experience teaching applied cryptography to engineering and computer science students and to professionals, and they make extensive use of examples, problems, and chapter reviews, while the book’s website offers slides, projects and links to further resources. This is a suitable textbook for graduate and advanced undergraduate courses and also for self-study by engineers.

Book Cryptography for Security and Privacy in Cloud Computing

Download or read book Cryptography for Security and Privacy in Cloud Computing written by Stefan Rass and published by Artech House. This book was released on 2013-11-01 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: As is common practice in research, many new cryptographic techniques have been developed to tackle either a theoretical question or foreseeing a soon to become reality application. Cloud computing is one of these new areas, where cryptography is expected to unveil its power by bringing striking new features to the cloud. Cloud computing is an evolving paradigm, whose basic attempt is to shift computing and storage capabilities to external service providers. This resource offers an overview of the possibilities of cryptography for protecting data and identity information, much beyond well-known cryptographic primitives such as encryption or digital signatures. This book represents a compilation of various recent cryptographic primitives, providing readers with the features and limitations of each.

Book ICSA Guide to Cryptography

Download or read book ICSA Guide to Cryptography written by Randall K. Nichols and published by McGraw-Hill Companies. This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the most important issues surrounding the Internet is the security issue. With the explosion of the Internet & the growth of global markets, every business that markets its products or uses computer networks for global communications & customer service must protect its assets & customer information. The most effective protection for information transmitted by or stored in computers is cryptography. This book is a detailed look at the uses of cryptography to protect commercial information.

Book Hacking Point of Sale

    Book Details:
  • Author : Slava Gomzin
  • Publisher : John Wiley & Sons
  • Release : 2014-02-03
  • ISBN : 1118810074
  • Pages : 313 pages

Download or read book Hacking Point of Sale written by Slava Gomzin and published by John Wiley & Sons. This book was released on 2014-02-03 with total page 313 pages. Available in PDF, EPUB and Kindle. Book excerpt: Must-have guide for professionals responsible for securing credit and debit card transactions As recent breaches like Target and Neiman Marcus show, payment card information is involved in more security breaches than any other data type. In too many places, sensitive card data is simply not protected adequately. Hacking Point of Sale is a compelling book that tackles this enormous problem head-on. Exploring all aspects of the problem in detail - from how attacks are structured to the structure of magnetic strips to point-to-point encryption, and more – it's packed with practical recommendations. This terrific resource goes beyond standard PCI compliance guides to offer real solutions on how to achieve better security at the point of sale. A unique book on credit and debit card security, with an emphasis on point-to-point encryption of payment transactions (P2PE) from standards to design to application Explores all groups of security standards applicable to payment applications, including PCI, FIPS, ANSI, EMV, and ISO Explains how protected areas are hacked and how hackers spot vulnerabilities Proposes defensive maneuvers, such as introducing cryptography to payment applications and better securing application code Hacking Point of Sale: Payment Application Secrets, Threats, and Solutions is essential reading for security providers, software architects, consultants, and other professionals charged with addressing this serious problem.

Book CISSP  Certified Information Systems Security Professional Study Guide

Download or read book CISSP Certified Information Systems Security Professional Study Guide written by James Michael Stewart and published by John Wiley & Sons. This book was released on 2011-01-13 with total page 927 pages. Available in PDF, EPUB and Kindle. Book excerpt: Totally updated for 2011, here's the ultimate study guide for the CISSP exam Considered the most desired certification for IT security professionals, the Certified Information Systems Security Professional designation is also a career-booster. This comprehensive study guide covers every aspect of the 2011 exam and the latest revision of the CISSP body of knowledge. It offers advice on how to pass each section of the exam and features expanded coverage of biometrics, auditing and accountability, software security testing, and other key topics. Included is a CD with two full-length, 250-question sample exams to test your progress. CISSP certification identifies the ultimate IT security professional; this complete study guide is fully updated to cover all the objectives of the 2011 CISSP exam Provides in-depth knowledge of access control, application development security, business continuity and disaster recovery planning, cryptography, Information Security governance and risk management, operations security, physical (environmental) security, security architecture and design, and telecommunications and network security Also covers legal and regulatory investigation and compliance Includes two practice exams and challenging review questions on the CD Professionals seeking the CISSP certification will boost their chances of success with CISSP: Certified Information Systems Security Professional Study Guide, 5th Edition.

Book Cryptography Engineering

Download or read book Cryptography Engineering written by Niels Ferguson and published by John Wiley & Sons. This book was released on 2011-02-02 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ultimate guide to cryptography, updated from an author team of the world's top cryptography experts. Cryptography is vital to keeping information safe, in an era when the formula to do so becomes more and more challenging. Written by a team of world-renowned cryptography experts, this essential guide is the definitive introduction to all major areas of cryptography: message security, key negotiation, and key management. You'll learn how to think like a cryptographer. You'll discover techniques for building cryptography into products from the start and you'll examine the many technical changes in the field. After a basic overview of cryptography and what it means today, this indispensable resource covers such topics as block ciphers, block modes, hash functions, encryption modes, message authentication codes, implementation issues, negotiation protocols, and more. Helpful examples and hands-on exercises enhance your understanding of the multi-faceted field of cryptography. An author team of internationally recognized cryptography experts updates you on vital topics in the field of cryptography Shows you how to build cryptography into products from the start Examines updates and changes to cryptography Includes coverage on key servers, message security, authentication codes, new standards, block ciphers, message authentication codes, and more Cryptography Engineering gets you up to speed in the ever-evolving field of cryptography.

Book Computer Security and Cryptography

Download or read book Computer Security and Cryptography written by Alan G. Konheim and published by John Wiley & Sons. This book was released on 2007-03-07 with total page 541 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gain the skills and knowledge needed to create effective data security systems This book updates readers with all the tools, techniques, and concepts needed to understand and implement data security systems. It presents a wide range of topics for a thorough understanding of the factors that affect the efficiency of secrecy, authentication, and digital signature schema. Most importantly, readers gain hands-on experience in cryptanalysis and learn how to create effective cryptographic systems. The author contributed to the design and analysis of the Data Encryption Standard (DES), a widely used symmetric-key encryption algorithm. His recommendations are based on firsthand experience of what does and does not work. Thorough in its coverage, the book starts with a discussion of the history of cryptography, including a description of the basic encryption systems and many of the cipher systems used in the twentieth century. The author then discusses the theory of symmetric- and public-key cryptography. Readers not only discover what cryptography can do to protect sensitive data, but also learn the practical limitations of the technology. The book ends with two chapters that explore a wide range of cryptography applications. Three basic types of chapters are featured to facilitate learning: Chapters that develop technical skills Chapters that describe a cryptosystem and present a method of analysis Chapters that describe a cryptosystem, present a method of analysis, and provide problems to test your grasp of the material and your ability to implement practical solutions With consumers becoming increasingly wary of identity theft and companies struggling to develop safe, secure systems, this book is essential reading for professionals in e-commerce and information technology. Written by a professor who teaches cryptography, it is also ideal for students.

Book Cryptography  The Key to Digital Security  How It Works  and Why It Matters

Download or read book Cryptography The Key to Digital Security How It Works and Why It Matters written by Keith Martin and published by W. W. Norton & Company. This book was released on 2020-05-19 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: A “must-read” (Vincent Rijmen) nuts-and-bolts explanation of cryptography from a leading expert in information security. Despite its reputation as a language only of spies and hackers, cryptography plays a critical role in our everyday lives. Though often invisible, it underpins the security of our mobile phone calls, credit card payments, web searches, internet messaging, and cryptocurrencies—in short, everything we do online. Increasingly, it also runs in the background of our smart refrigerators, thermostats, electronic car keys, and even the cars themselves. As our daily devices get smarter, cyberspace—home to all the networks that connect them—grows. Broadly defined as a set of tools for establishing security in this expanding cyberspace, cryptography enables us to protect and share our information. Understanding the basics of cryptography is the key to recognizing the significance of the security technologies we encounter every day, which will then help us respond to them. What are the implications of connecting to an unprotected Wi-Fi network? Is it really so important to have different passwords for different accounts? Is it safe to submit sensitive personal information to a given app, or to convert money to bitcoin? In clear, concise writing, information security expert Keith Martin answers all these questions and more, revealing the many crucial ways we all depend on cryptographic technology. He demystifies its controversial applications and the nuances behind alarming headlines about data breaches at banks, credit bureaus, and online retailers. We learn, for example, how encryption can hamper criminal investigations and obstruct national security efforts, and how increasingly frequent ransomware attacks put personal information at risk. Yet we also learn why responding to these threats by restricting the use of cryptography can itself be problematic. Essential reading for anyone with a password, Cryptography offers a profound perspective on personal security, online and off.

Book Fundamentals of Cryptology

    Book Details:
  • Author : Henk C.A. van Tilborg
  • Publisher : Springer Science & Business Media
  • Release : 1999-12-31
  • ISBN : 0792386752
  • Pages : 496 pages

Download or read book Fundamentals of Cryptology written by Henk C.A. van Tilborg and published by Springer Science & Business Media. This book was released on 1999-12-31 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: The protection of sensitive information against unauthorized access or fraudulent changes has been of prime concern throughout the centuries. Modern communication techniques, using computers connected through networks, make all data even more vulnerable for these threats. Also, new issues have come up that were not relevant before, e. g. how to add a (digital) signature to an electronic document in such a way that the signer can not deny later on that the document was signed by him/her. Cryptology addresses the above issues. It is at the foundation of all information security. The techniques employed to this end have become increasingly mathematical of nature. This book serves as an introduction to modern cryptographic methods. After a brief survey of classical cryptosystems, it concentrates on three main areas. First of all, stream ciphers and block ciphers are discussed. These systems have extremely fast implementations, but sender and receiver have to share a secret key. Public key cryptosystems (the second main area) make it possible to protect data without a prearranged key. Their security is based on intractable mathematical problems, like the factorization of large numbers. The remaining chapters cover a variety of topics, such as zero-knowledge proofs, secret sharing schemes and authentication codes. Two appendices explain all mathematical prerequisites in great detail. One is on elementary number theory (Euclid's Algorithm, the Chinese Remainder Theorem, quadratic residues, inversion formulas, and continued fractions). The other appendix gives a thorough introduction to finite fields and their algebraic structure.