This book, "Cryptography Theory and Practice," third edition by Douglas R. Stinson, provides a comprehensive overview of cryptography, covering both theoretical foundations and practical applications. It begins with classical cryptography, discussing various simple cryptosystems such as shift, substitution, affine, Vigenère, Hill, and permutation ciphers, along with their cryptanalysis. The book then moves on to Shannon's theory, introducing concepts like perfect secrecy, entropy, and unicity distance, and explores product cryptosystems. Next, it delves into block ciphers and the Advanced Encryption Standard (AES), explaining substitution-permutation networks, linear and differential cryptanalysis, and the structure and analysis of DES and AES. The text then covers cryptographic hash functions, discussing their role in data integrity, security, and message authentication codes, as well as unconditionally secure MACs. The book continues with the RSA cryptosystem and factoring integers, exploring public-key cryptography, number theory, primality testing, and factoring algorithms. It also covers discrete logarithms, elliptic curves, and the security of ElGamal systems. The final chapters discuss digital signature schemes, pseudo-random number generation, identification schemes, key distribution, key agreement, public-key infrastructure, secret sharing schemes, multicast security, and copyright protection. The book is structured with chapters, sections, and exercises, providing a thorough understanding of cryptographic principles and their practical implementations. It is a valuable resource for students and professionals in the field of cryptography and computer security.This book, "Cryptography Theory and Practice," third edition by Douglas R. Stinson, provides a comprehensive overview of cryptography, covering both theoretical foundations and practical applications. It begins with classical cryptography, discussing various simple cryptosystems such as shift, substitution, affine, Vigenère, Hill, and permutation ciphers, along with their cryptanalysis. The book then moves on to Shannon's theory, introducing concepts like perfect secrecy, entropy, and unicity distance, and explores product cryptosystems. Next, it delves into block ciphers and the Advanced Encryption Standard (AES), explaining substitution-permutation networks, linear and differential cryptanalysis, and the structure and analysis of DES and AES. The text then covers cryptographic hash functions, discussing their role in data integrity, security, and message authentication codes, as well as unconditionally secure MACs. The book continues with the RSA cryptosystem and factoring integers, exploring public-key cryptography, number theory, primality testing, and factoring algorithms. It also covers discrete logarithms, elliptic curves, and the security of ElGamal systems. The final chapters discuss digital signature schemes, pseudo-random number generation, identification schemes, key distribution, key agreement, public-key infrastructure, secret sharing schemes, multicast security, and copyright protection. The book is structured with chapters, sections, and exercises, providing a thorough understanding of cryptographic principles and their practical implementations. It is a valuable resource for students and professionals in the field of cryptography and computer security.