Introduction

Introduction

Modern life can make you paranoid . Hardly a day goes by that you don't hear that all of a company's e-mail has been seized and used in a lawsuit or that some employee has been fired for inappropriate e-mail. You hear about credit card numbers and passwords hijacked from e-mail. You also hear about vicious, nasty, evil viruses prop agated by e-mail that appears to come from people you know.

Some of these problems exist because people (Microsoft) are putting too much capability into e-mail clients (Outlook). There really is no reason you need your e-mail to launch applications embedded in a message! Sure, it's nifty and cool, but it is also how these evil programs spread around.

Even so, there is one way to protect yourself fully from evil, nasty e-mail viruses, and evil, nasty password thieves , and evil, nasty lawyers , and evil, nasty employers , and even, possibly, evil, nasty foreign governments , if you're that paranoid. All of this safety can be found from one free, open program: GNU Privacy Guard, or GPG.

GPG's name is a bit of a tweak on an earlier, and formerly free, security package that was called PGP, for "Pretty Good Privacy." The authors of PGP chose to take their product closed and commercial (something that cannot be done with code licensed under the GPL; see Defining Free in Chapter 1 ). Not long thereafter, the GNU Privacy Guard project started. GPG is compatible with PGP and is completely free and published under the GPL.

GPG delivers you from the horrors of e-mail with two basic mechanisms: strong encryption and digital signatures. Encryption involves scrambling the content of your message so that none but the intended recipients are able to read it. Digital signatures verify the identity of the sender and validate that the message is intact (and has not been changed or defaced in transit by third parties). This is not cryptography like the puzzle in the daily paper. It is not a simple substitution cipher. It is, in fact, encryption so thorough that it should be impossible to tell the difference between an encrypted message and a stream of random noise. GPG provides this level of encryption.