本書序言Up-to-date, engaging coverage of essential topics●Expanded coverage of cryptography including Elliptic curve photography; coverage of knapsack ciphers has been removed. Also, the important notion of homomorphic encryption is introduced in this edition.●Coverage of recent numerical discoveries, including four new Mersenne primes; the largest known twin primes; the evidence supporting many important conjectures, and more.●Coverage of new theoretical discoveries, such as the proof of weak Goldbach conjecture and the result that there is an algorithm to multiply two n-bit integers using O (nlog2 n) bit operations.A proven approach●Enhanced exercise sets have been examined and improved sets even further, plus several hundred new exercises, from routine to challenging. New computational and exploratory exercises are included.●Connections with abstract algebra: The book does not assume prior knowledge of abstract algebra, but introduces some basic algebraic structures such as gr