Cyber security is the protection of information systems, hardware, software, and information as well from theft, damages, interruption or misdirection to any of these resources. In other words, cyber security focuses on protecting computers, networks, programs and data (in use, in rest, in motion) from unauthorized or unintended access, change or destruction. Therefore, strengthening the security and resilience of cyberspace has become a vital homeland security mission. Cyber security attacks are growing exponentially. Security specialists must occupy in the lab, concocting new schemes to preserve the resources and to control any new attacks. Therefore, there are various emerging algorithms and techniques viz. DES, AES, IDEA, WAKE, CAST5, Serpent Algorithm, Chaos-Based Cryptography McEliece, Niederreiter, NTRU, Goldreich-Goldwasser-Halevi, Identity Based Encryption, and Attribute Based Encryption. There are numerous applications of security algorithms like cyber security, web security, e-commerce, database security, smart card technology, mobile security, cloud security, digital signature, etc. The book offers comprehensive coverage of the most essential topics, including: Modular Arithmetic, Finite Fields Prime Number, DLP, Integer Factorization Problem Symmetric Cryptography Asymmetric Cryptography Post-Quantum Cryptography Identity Based Encryption Attribute Based Encryption Key Management Entity Authentication, Message Authentication Digital Signatures Hands-On "SageMath" This book serves as a textbook/reference book for UG, PG, PhD students, Teachers, Researchers and Engineers in the disciplines of Information Technology, Computer Science and Engineering, and Electronics and Communication Engineering.

Opportunistic networks allow mobile users to share information without any network infrastructure.This book is suitable for both undergraduates and postgraduates as it discusses various aspects of opportunistic networking including, foundations of ad hoc network; taxonomy of mobility models, etc.

One of the issues that arise in the text steganography is the capacity of hiding secret bit. Focusing in Arabic text steganography we propose a sharp-edges method to encounter the issue. This new method will hide the secret bits in the sharp-edges for each character in the Arabic text document. The stego-text for this method has high invisibility, and therefore it is possible to be published publicly. We introduce keys to determine the position of the secret bit randomly. This method utilizes the advantages of the Arabic text for steganography and can also be implemented to the same text scripting of languages such as Jawi, Persian or Urdu.