Preface

Cryptographic techniques are important due to the increasing digitization of most realworld applications. Lightweight cryptographic techniques suitable for devices with low computational capabilities that require fast computation are emerging due to the development of the Internet of things (IoT), 5G networks, and cloud computing. Since most organizations are opting for e-business models, suitable cybersecurity approaches and policies depending upon the nature and volume of business are needed. This book includes seven chapters that discuss various cryptographic techniques suitable for software-defined networks in the Internet of Things (SDN-IoT), Internet of Multimedia Things (IoMT), and SMS4-BSK pipelined cryptosystems. In addition, the book discusses intelligent cybersecurity threat management in modern information systems, keyless encryption techniques, and the differences between encrypted and non-encrypted data.

Due to the emergence of 5G networks, a new kind of network architecture referred to as SDN-IoT has been developed. In Chapter 1, the authors discuss SDN and IoT as well as lightweight cryptography, including hardware, throughput, latency, power consumption, and memory management. It also examines the three layers of SND-IoT (control layer, infrastructure layer, and application layer) and their security requirements in terms of lightweight cryptographic techniques suitable for 5G networks.

Encryption of image and video that is multimedia data is one of the challenging tasks in IoT due to its low computing capability. In Chapter 2, the authors discuss the chaosbased image and video encryption in IoT and address various issues of the IoM. They present a literature review of AES and its variant-based encryption methods along with a discussion of texture encryption and PLIE methods.

Lightweight cryptography can be achieved by a few mechanisms, among which pipeline cryptosystems play an important role. SMS4-BSK is a kind of pipeline cryptosystem designed to provide faster encryption with the required security in lightweight devices. In Chapter 3, the authors discuss SMS4-BSK cryptosystems and their real-time applications.

Encryption of digital images is one of the important tasks in cryptography. In Chapter 4, the authors provide a comprehensive overview of image encryption. The keys used for encryption are generated using a secure hash function and encryption is carried out using the AES algorithm. Key sharing is done using RSA.

Cybersecurity threat management is an essential requirement for various organizations. The cybersecurity policies to protect a business and its data are dependent upon the nature and volume of the business. In Chapter 5, the authors present several modern threat management frameworks and policies. They discuss various types of malware threats such as adware, spyware, ransomware, backdoors, and logic booms. They also examine reconnaissance tools such as social engineering and DNS harvesting tools. Furthermore, they discuss cloud-based security services.

Keyless cryptography is one of the alternatives to public key cryptography. Decryption in keyless cryptography is carried out only when all the secret shares are brought back. In Chapter 6, the authors survey various keyless cryptography mechanisms and present a few important mechanisms chapter using illustrations. These mechanisms include Shamir's protocol, Dean and Goldsmith cryptosystem, and EVS Key scheme. The authors also proposed a novel key sharing protocol and presented simulation results.

Distinguishing encrypted from non-encrypted data is one of the important tasks in cybercrime investigation to help police to recover deleted data. In Chapter 7, the authors examine various techniques for distinguishing between encrypted and unencrypted data (stream data and static data). They present a chi-squared distribution-based approach as well as propose a changed-point statistics-based method that they experimentally analyze.

This book is useful for graduate engineering students and researchers in computer science and electrical engineering as well as practicing engineers in the field of information and cybersecurity.

I would like to express my sincere thanks to all the authors for their contributions and efforts to bring about this wonderful book. My earnest gratitude and appreciation go to the staff at IntechOpen, particularly Author Service Manager Ms. Martina Ivancic. I would like to express my heartfelt thanks to the management, secretary, and principal of my institute and my department's faculty members. Finally, dearest thanks to my family members, especially my cute daughter Abirami.

> **Dr. Srinivasan Ramakrishnan,** Professor and Head, Department of Information Technology, Dr. Mahalingam College of Engineering and Technology, Pollachi, India

Section 1

Lightweight Cryptographic

Techniques
