Use of the Internet is expanding beyond anyone's expectations. As corporations, government offices, and ordinary citizens begin to rely on the information highway to conduct business, they are realizing how important it is to protect their communications -- both to keep them a secret from prying eyes and to ensure that they are not altered during transmission. Encryption, which until recently was an esoteric field of interest only to spies, the military, and a few academics, provides a mechanism for doing this.

PGP, which stands for Pretty Good Privacy, is a free and widely available encryption program that lets you protect files and electronic mail. Written by Phil Zimmermann and released in 1991, PGP works on virtually every platform and has become very popular both in the U.S. and abroad. Because it uses state-of-the-art public key cryptography, PGP can be used to authenticate messages, as well as keep them secret. With PGP, you can digitally "sign" a message when you send it. By checking the digital signature at the other end, the recipient can be sure that the message was not changed during transmission and that the message actually came from you.

PGP offers a popular alternative to U.S. government initiatives like the Clipper Chip because, unlike Clipper, it does not allow the government or any other outside agency access to your secret keys.

PGP: Pretty Good Privacy by Simson Garfinkel is both a readable technical user's guide and a fascinating behind-the-scenes look at cryptography and privacy. Part I, "PGP Overview," introduces PGP and the cryptography that underlies it. Part II, "Cryptography History and Policy," describes the history of PGP -- its personalities, legal battles, and other intrigues; it also provides background on the battles over public key cryptography patents and the U.S. government export restrictions, and other aspects of the ongoing public debates about privacy and free speech. Part III, "Using PGP," describes how to use PGP: protecting files and email, creating and using keys, signing messages, certifying and distributing keys, and using key servers. Part IV, "Appendices," describes how to obtain PGP from Internet sites, how to install it on PCs, UNIX systems, and the Macintosh, and other background information. The book also contains a glossary, a bibliography, and a handy reference card that summarizes all of the PGP commands, environment variables, and configuration variables.

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The second half explains PGP usage and where you can find it online. Unfortunately, a lot of this seems dated -- however, to be fair, the book is over five years old. You'll probably be better off with another resource such as the included documentation.

13 of 15 found the following review helpful:

Not up to O'Reilly's StandardsMay 03, 2000

My usual rule is to buy anything published by O'Reilly--it's always worth it. Not this time.

Garfinkel's book is extremely basic. It covers the same ground as the PGP documentation, but not as well. Worse, it's badly out of date by now.

A much better bet is to read the online documentation for GnuPG, the free PGP clone, at www.gnupg.org. If you use UNIX, you should use GPG instead of PGP anyway: PGP has a wonderful interface under Windows, but has really stagnated for UNIX users.

7 of 7 found the following review helpful:

A good PGP and cryptography primerJun 28, 2003
By Gerald Ford "pho_kin"
PGP is a fascinating tool. Most see PGP as a way of sharing files, but the creator of PGP, Phil Zimmerman, really want to make a *privacy* tool. I did not realize this and other things until reading this book.

O'Reilly's PGP book can be divided into two sections. The first section is really a history of cryptography and how PGP fits in this context. I found this section surprisingly enjoyable as you learn about the long and tortuous struggle between the NSA and people who want to promote freedom and privacy. On a more concrete level though, you do learn quite a bit about different encryption algorithms and key algorithms, such as the RSA and Diffie-Hellman as well as other concepts important to cryptography. Admittedly, the history itself makes for pretty interesting reading.

The second section is about PGP usage, and it is very thorough in its coverage. You will learn just about every possible feature in PGP, and how to apply them to a number of possible situations. I like reading this book over the PGP manuals just for the time and care put into it, if not the amusing examples.

One thing other reviewers have rightly touched on is the age of the book. TIme has passed. The RSA algorithm is now free and open, and PGP clone called GPG is now in wide use. I am definitely excited to see a 2nd edition of this book in hopes that it will cover such things.

However, regardless of the age, this book is an excellent primer into PGP and cryptography culture, and newbies like me will certain enjoy reading it.

5 of 5 found the following review helpful:

Dated but useful nonethelessSep 07, 2000
By Keith Tokash "twigles"
This book gives an excellent account of how encryption came into the hands of non-spooks (and I don't mean Clipper). But what really matters is the legacy information on how encryption works. This information hasn't changed since. It also gives the reader a solid base of understanding of what PGP is doing when you use it.

The book is also quite simple to read, so much so that I felt guilty for "studying" a book that was so easy that I could blow through a chapter in twenty minutes. One final note of importance is that because the book is old (94), it is UNIX-centric, which is quite refreshing in today's environment of applications written exclusively for Windoze.

7 of 8 found the following review helpful:

Yet another O'Reilly masterpieceFeb 04, 1999

Having read a poor review of this book on Amazon, I was a little reluctant to purchase. However, it appears that the addage of "one mans meat is another mans poisen" holds true here. Perhaps it is because I am new to pgp, but I really enjoyed the history portion of the book. I also found the descriptive part of this book to be exactly the information I needed to start putting pgp to good use. Without hesitation, I would recommend this book.

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