Marius Iulian Mihailescu - Pro Cryptography and Cryptanalysis: Creating Advanced Algorithms with C# and .NET

Any source code or other supplementary material referenced by the author in this book is available to readers on GitHub via the books product page, located at www.apress.com/9781484263662 . For more detailed information, please visit www.apress.com/source-code .

Information represents one of the most important aspects that need to be taken into consideration when complex systems are designed and implemented, such as business, organizations, and military operations. Information that falls into the wrong hands can be a disaster and can lead to a huge loss of business or catastrophic results. In order to secure communication, cryptology (cryptography and cryptanalysis) can be used to cipher information.

Due to the rapid growth of electronic communication, the issues in information security are increasing every day. Messages that are exchanged over worldwide, publicly accessible computer networks must be protected and retained and must also have protection mechanisms against manipulation. Electronic business requirements consist of having digital signatures that are recognized by the law. With the help of modern cryptography, we have solutions to all of these problems.

This book was borne from cryptography courses (theoretical and applied cryptography) given to students (graduate and undergraduate levels) in computer science at the University of Bucharest and Titu Maiorescu University; business experience at national and international companies; ethical hacking best practices; and security audits. The book it is intended to cover the most advanced cryptography and cryptanalysis techniques together with their implementations using C# and the .NET Framework, giving a practical perspective, helping readers to think of cryptography and cryptanalysis techniques in terms of practice. Some of the implementations in C# will be given using the new features of C# 8.0 (see Chapter ). As an advanced and exhaustive book, serving as a comprehensive guide to the most important topics in security information, cryptography, and cryptanalysis, the book can be used for a wide range of purposes and areas by multiple professionals, such as security experts with their audits, military experts and personnel, ethical hackers, teachers in academia, researchers, software developers, and software engineers when security and cryptographic solutions need to be implemented in a real business software environment; student courses (undergraduate and graduate levels, master degree, professional and academic doctoral degree); business analysts, and many more.

We consider it useful to define some of the main notions we will work with throughout the book.

CRYPTOGRAPHY represents the defensive side of cryptology. Its main objective is to create and design the cryptographic systems and their rules. Cryptography can be seen as the art of protecting the information by transforming it into an unreadable format called cipher text.

CRYPTANALYSIS represents the offensive side of cryptology. Its main objective is to study the cryptographic systems with the goal of providing necessary characteristics in such a way as to fulfill the function for which they have been designed. Cryptanalysis has the possibility to analyze the cryptographic systems of third parties through the cryptograms realized with them, in such way that breaking them obtains useful information for their business purposes. The people who are dealing with this field are known as cryptanalysts, code breakers, or ethical hackers.

CRYPTOLOGY represents the science or art of secret writings. Its main objective is to protect and defend the secrets of the data and the confidentiality of the information with the help of cryptographic algorithms.

The book examines all three sides from a practical side with references to the theoretical background by illustrating how a theoretical algorithm should be exploited and spread in order to be implemented.

The book has 24 chapters divided within three parts (see Table shows how to read the book and what chapters depend on each other.

In Part I - Foundations (Chapters, we cover a collection of basic key elements on complexity theory, probability theory, information theory, number theory, abstract algebra, and finite fields.

Chapters deal with integer arithmetic and floating-point arithmetic processing and algorithms. The importance of these chapters is quite vital, and other chapters and algorithm implementations are dependent on the content of these chapters.

In Chapter, we discuss the newest features and enhancements of C# 8.0. We present how the features and enhancements play an important role in developing cryptography and cryptanalysis algorithms and methods. We cover readonly members, default interface methods, pattern matching enhancements, how to use the new type of declarations, static local functions, disposable ref types, nullable reference types, asynchronous streams, indices and ranges, null-coalescing assignments, unmanaged constructed types, stackalloc in nested expressions, and enhancement of interpolated verbatim strings.