PGP: Pretty Good Privacy aims to make cryptography — in the form of PGP — accessible by everyone. Since doing encryption properly requires some understanding of the basic concepts involved, it begins with a general introduction to cryptography. Here Garfinkel's exposition is as good as any I have seen: it is clearly laid out and well illustrated, and doesn't assume any mathematical competence. The history of public-key cryptography and the associated battles over patents and royalties is also covered. The actual guide to using PGP errs (if at all) on the side of thoroughness, describing in detail, with examples, how to generate, manage, use, and register PGP keys. The appendices explain where to find and install the different versions of PGP (DOS/Unix/Macintosh), and go into the mathematics in a little more detail. Readers who already understand public-key cryptography and are accustomed to using on-line documentation will probably find much of this unnecessary or overly verbose; it is certainly not aimed at hackers. Given a copy of PGP: Pretty Good Privacy, however, I think almost anyone should be able to use cryptography, and this is a better measure of its success.