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This book provides comprehensive coverage of various Cryptography topics, while highlighting the most recent trends such as quantum, blockchain, lightweight, Chaotic and DNA cryptography. Moreover, this book covers cryptography primitives and its usage and applications and focuses on the fundamental principles of modern cryptography such as Stream Ciphers, block ciphers, public key algorithms and digital signatures. Readers will gain a solid foundation in cryptography and security. This book presents the fundamental mathematical concepts of cryptography. Moreover, this book presents hiding data techniques such as steganography and watermarking. The author also provides a comparative study of the different cryptographic methods, which can be used to solve security problems.

Chapter 1. Introduction to Cyber Security

Abstract
Today, cryptography plays a vital role in every electronic and communication system. Everyday many users generate and interchange large amount of information in various fields through the Internet, telephone conversations, and e-commerce transactions. In modern system-on-chips (SoCs), cybersecurity plays an integral role in protecting the confidentiality and integrity of information. Cybersecurity is protecting computers, servers, mobiles, networks, electronic devices, and data from malicious attacks [1]. Recent years have seen an unfortunate and disruptive growth in the number of cyber-attacks. There are mainly three threats to data security [2, 3]:
Khaled Salah Mohamed

Chapter 2. Cryptography Concepts: Confidentiality

Abstract
The term cryptography is derived from the Greek word Kryptos. Kryptos is used to describe anything that is hidden, veiled, secret, or mysterious. Cryptography is the study of mathematical techniques for the secure transmission of a private message over an insecure channel. Cryptography is the basic technique to secure our data from different kind of attackers like: interruption, modification, fabrication, etc. It has been around for 2000+ years. They were shaving the slave’s head, tattooed the message on it, and let the hair grow [1]. The first documented use of cryptography in writing dates back to circa 1900 B.C. when an Egyptian scribe used nonstandard hieroglyphs in an inscription. Some experts argue that cryptography appeared spontaneously sometime after writing was invented, with applications ranging from diplomatic missives to war-time battle plans. Caesar’s cipher: shifting each letter of the alphabet by a fixed amount. It is easy to break. Vigenere’s polyalphabetic cipher generalizes Caesar’s shift cipher. It uses keyword to select encrypting rows. Substitution cipher: permutations of 26 letters, using the dictionary. It is easy to break. Then in modern era, we have many cryptography algorithms as we will explain in the rest of this chapter. Modern cryptography algorithms are based over the fundamental process of factoring large integers into their primes, which is said to be intractable [2, 3]. In both symmetric and asymmetric cryptosystems, encryption is the process of changing the original form of text to unreadable form and decryption process gets the original form of data from the meaningless text. For block cipher, use of plaintext and ciphertext of equal size avoids data expansion. In this chapter, confidentiality will be addressed. Encryption is the major tool to achieve confidentiality [4–6].
Khaled Salah Mohamed

Chapter 3. Cryptography Concepts: Integrity, Authentication, Availability, Access Control, and Non-repudiation

Abstract
To validate the integrity of the data transmitted over the channel, message authentication code (MAC) is used for checking the messages and the authentication, ensuring that the integrity of the information has not been modified under the transmission.
Khaled Salah Mohamed

Chapter 4. New Trends in Cryptography: Quantum, Blockchain, Lightweight, Chaotic, and DNA Cryptography

Abstract
DNA cryptography is a promising and rapid emerging field in data security. DNA cryptography may bring forward a new hope for unbreakable algorithms. DNA cryptology combines cryptology and modern biotechnology. To encrypt using DNA, sender generates a DNA encoding table, and receiver generates another table through the same encoding technique and sends a clue to the sender to be able to generate it locally. The plaintext to be encoded is divided into two halves equally. If the plaintext is not even, we insert random padding. One half of the plaintext is converted into DNA sequence using sender-based table, and the other half of the plaintext is converted into DNA sequence using receiver-based table. DNA cryptography is a bio-inspired novel technique used for securing end to end communication, where DNA is used as an information carrier. DNA cryptography is assumed to be unbreakable algorithm [23–26]. The advantages of DNA computing over traditional computing are as follows [27]:
Khaled Salah Mohamed

Chapter 5. Data Hiding: Steganography and Watermarking

Abstract
In era of information society, protection system can be classified into more specific as hiding information (steganography or watermarking) or encryption information (cryptography) or a combination between them. Cryptography and steganography are well-known and broadly used techniques that use information in order to cipher or cover their existence, respectively. Comparison between cryptography and information hiding techniques is shown in Fig. 5.1. Information hiding is a technique of hiding secret using redundant cover data such as images, audios, movies, documents, etc.
Khaled Salah Mohamed

Chapter 6. Conclusions

Abstract
In this book, the fundamentals of cryptography are discussed. It provides a comprehensive study of the three critical aspects of security: confidentiality, integrity, and authentication. As it is known, cryptography plays a vital and critical role in achieving the primary aims of security goals, such as authentication, integrity, confidentiality, and no-repudiation. Cryptographic algorithms are developed in order to achieve these goals as discussed during this book. Moreover, this book discusses the fundamentals of private and public key cryptography. Moreover, it explains the details of the main building blocks of these cryptographic systems. Besides, this chapter explores the different crypto-analysis techniques. It addresses stream ciphers, DES and 3DES, AES, block ciphers, the RSA cryptosystem, and public key cryptosystems based on the discrete logarithm problem, ECC, key exchange algorithms, and so many other algorithms. Moreover, this chapter provides a comparison between different encryption algorithms in terms of speed encryption, decoding, complexity, the length of the key, structure, and flexibility. This book explores different cryptography concepts such as authentication, integrity, availability, access control, and non-repudiation. It presents concepts of digital signatures, hash functions, and MACs. Finally, this book discusses the cutting-edge cryptographic techniques such as quantum cryptography, DNA cryptography, chaotic cryptography, lightweight cryptography, and blockchain cryptography. All these cryptography techniques are promising and rapid emerging fields in data security.
Khaled Salah Mohamed