Most helpful positive review
A good approach
on February 23, 2003
This is a math book. It tells you cryptography-related abstract algebra, number theory, etc. The good thing is it doesn't assume you have much math background.
On the other hand, it has a lot of errors. Some are just typos, some not. Personally, I think if a math book has a single math error (wrong lemma, incorrect logic, ...), it is not a qualified math book. Unfortunately, this book has more than one.
The reason I still give it four stars is that I like its approach. Without math, cryptography is not cryptography. If you don't have enough math background, this book really helps you get started. There are simply not many choices on the market of this kind. After reading this, you can go to more rigorous, advanced ones, such as Koblitz's series. An alternative (more rigorous, less abstract algebra) is Bauer's. All Koblitz's and Bauer's are excellent.