This book is an introduction to modern ideas in cryptology and how to employ
these ideas. It includes the relevant material on number theory, probability, and
abstract algebra, in addition to descriptions of ideas about algorithms and com
plexity theory. Three somewhat different terms appear in the discussion of secure
communications and related matters: cryptography, cryptanalysis, and cryptology.
The first, cryptography, refers to writing using various methods to keep the message
secret, as well as more modern applications of these methods. By contrast, crypt
analysis is the science of attacking ciphers, finding weaknesses, or possibly proving
that there are none. Cryptology covers both, and is the most inclusive term.
This unique book explains the basic issues of classical and modern cryptography, and provides a self contained essential mathematical background in number theory, abstract algebra, and probability—with surveys of relevant parts of complexity theory and other things. A user-friendly, down-to-earth tone presents concretely motivated introductions to these topics. More detailed chapter topics include simple ciphers; applying ideas from probability; substitutions, transpositions, permutations; modern symmetric ciphers; the integers; prime numbers; powers and roots modulo primes; powers and roots for composite moduli; weakly multiplicative functions; quadratic symbols, quadratic reciprocity; pseudoprimes; groups; sketches of protocols; rings, fields, polynomials; cyclotomic polynomials, primitive roots; pseudo-random number generators; proofs concerning pseudoprimality; factorization attacks finite fields; and elliptic curves. For personnel in computer security, system administration, and information systems.