"This book explains the mathematical foundations of public key cryptography in a mathematically correct and thorough way without omitting important practicalities. ... I would like to emphasize that the book is very well written and quite clear. Topics are well motivated, and there are a good number of examples and nicely chosen exercises. To me, this book is still the first-choice introduction to public-key cryptography." (Klaus Galensa, Computing Reviews, March, 2015) "This is a text for an upper undergraduate/lower graduate course in mathematical cryptography. ... It is very well written and quite clear. Topics are well-motivated, and there are a good number of examples and nicely chosen exercises. ... An instructor of a fairly sophisticated undergraduate course in cryptography who wants to emphasize public key cryptography should definitely take a look at this book." (Mark Hunacek, MAA Reviews, October, 2014)