The first edition of this book, which was published in 1995, contained thirteen
chapters. My objective was to produce a general textbook that treated all the
essential core areas of cryptography, as well as a selection of more advanced
topics. In writing the book, I tried to design it to be flexible enough to permit
a wide variety of approaches to the subject, so that it could be used for boih
undergraduate and graduate university courses in cryptography in mathematics,
computer science and engineering departments.
The second edition, published in 2002, was focused more tightly on the core
areas of cryptography that are most likely to be covered in a course. In contrast to
the first edition, the second edition contained only seven chapters. At that time,
my intention was to write a companion volume containing updated treatments of
other chapters from the first edition, as well as chapters covering new topics.
Eventually, I changed my plans and I decided to proceed directly to a one-
volume, expanded third edition. This third edition more closely resembles the first
edition in its breadth and scope, bui it has been almost completely rewritten. It
consists of the seven chapters from the second edition, updated where appropriate,
and seven new chapters.
