## About the course

Professor Debdeep Mukhopadhyay, a faculty from the department of Computer Science and Engineering at the Indian Institute of Technology, Kharagpur has designed this course on Cryptography and Network Security covering all the fundamental concepts of Cryptography and Network Security. The term Cryptography which translates as "secret writing," refers to the science of concealing the meaning of data, so that only specified parties understand a transmission's contents. Cryptography has existed for thousands of years; for most of history, however, the users of cryptography were associated with a government or organized group and were working to conceal secret messages from enemies. These days, millions upon millions of secure, encoded transmissions happen online each day and cryptographic standards are used to protect banking data, health information, and much more. Without cryptography, e-commerce as we know it would be impossible. Since online security threats evolve so quickly, there are dozens of different schools of thought on how best to use encryption to enhance network security not just for governments, but for businesses and end users, too. This course comprises of video lectures which can be viewed online and offline as per the convenience of the user. It also has questions/assignments for hands on practice. So, this makes it all together a complete package.

In this course, the user will learn about the underlying principles of cryptography and network security. In addition to this, it develops the mathematical tools required to understand the topic of cryptography. Beginning from the classical ciphers to modern day ciphers, the course extensively covers the techniques and methods required for the proper functioning of the ciphers. The course also covers the construction and cryptanalysis of block ciphers, stream ciphers and hash functions. This course also defines one way functions and trap-door functions and presents the construction and cryptanalysis of public key ciphers, namely RSA. The key exchange problem and solutions using the Diffie-Hellman algorithm are discussed. Message Authentication Codes (MAC) and signature schemes are also detailed. The course covers the modern trends in asymmetric key cryptography, namely using Elliptic Curves. The course concludes with the design rationale of network protocols for key exchange and attacks on such protocols.