A 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

This book is an outstanding introduction to cryptographic techniques and algorithms Although it's labelled as a "graduate text in mathematics", most of it should be accessible to anyone who knows a little linear algebra. For readers just interested in the how-to of the algorithms, not even that is needed. Koblitz does a thorough job of leading up to each algorithm and proving its formal properties. He also presents the algorithms themselves, unencumbered by denser material of interest to mathematicians.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.

This is an excellent book fot those, who are interested in the theoretical background of cryptography. It was also my first book in number theory, and I had no trouble following most of the text ( except the chapter on Elliptic curves, which -as I realize now- IS difficult)Highly recommendable! A pleasant surprise is, that there are virtually no typos.

This is a truly lovely book written by Koblitz. I agree with some of the comments made by earlier reviewers that the content might be outdated, however, it is important to realize that this book is there for building one's foundation in number theory and cryptography. After one is done doing that, one can go and read the current literature in cryptography. I have used this book for a graduate crypto course at USC, and I think it really helped me a lot. This book is a great reference and a great buy.

Neal Koblitz. The name says all. He is the cocreator of the elliptic curve cryptosystems. If you have studied 1 year of college algebra (Herstein or Fraleigh) and you want to learn cryptography mathematically, this is THE reference. If you are an engineer and/or just want to know the practical (and as always, superficial) issues of the subject, skip it.