Highly recommendable! A pleasant surprise is, that there are virtually no typos.Koblitz's Course in Number Theory and Cryptography This book is a real gem - very clearly written and covering the subject matter concisely but comprehensively. Particularly welcome are the exercises which are ingenious and extend the subject matter rather than just test knowledge of the chapter. It is extremely helpful too (and rare in a graduate text book) that solutions to all of the problems are provided at the back of the book. Exceptionally, and again very helpfully, there seem to be zero errors/typos in the text. Strongly recommended as the best introduction to this fascinating and important field
The book covers a variety of topics - public-key encryption, primality testing, factoring, and cryptographic protocols. It introduces zero-knowledge proofs and blind transfer, techniques that offer real hope of personal privacy in a world where data transfer is mandatory. I was a little disappointed by the chapters on elliptic cryptography, however. I hoped that Koblitz would bring is explanatory powers to bear on the algorithms. Somehow, I never quite connected with his descriptions of elliptic curves - perhaps I'm just thick, or perhaps a bit more introductory material would have helped.
The rest of the book is a very fine example of clear, readable math writing. Its clarity its range of topics earn it a place with anyone interested in cryptography, factoring, and prime numbers.