Introduction to Protocol Building Blocks In Cryptography

Abstract

The Whole point of cryptography is to solve problems. It solves problems that involve secrecy, authentication ,integrity and dishonest people .A protocol Is a series of steps ,involving two or more parties designed to accomplish a task. A series of steps means that the protocol has a sequence, from start to finish. Analyzing stream ciphers is often easier than analyzing block ciphers. For example, one important metric used to analyze LFSR-based generators is linear complexity, or linear span. This is defined as the length, n, of the shortest LFSR that can mimic the generator output. Any sequence generated by a finite-state machine over a finite field has a finite linear complexity [1006]. Linear complexity is important because a simple algorithm, called the Berlekamp-Massey algorithm, can generate this LFSR after examining only 2n bits of the keystream [1005]. Once you’ve generated this LFSR, you’ve broken the stream cipher.