|
|
|
|
Encryption Now we arrive at the strongest defense: encryption. It scrambles things so that only someone with the right key may unscramble it. Why encryption? Even if you maintain a perfectly secure home computer, any time you send something across the Internet, you lose control. You become dependent on the security of other people's computers. PGP (Pretty Good Privacy) is the most popular encryption program. You can download free versions for almost any operating system from http://pgp.com/products/freeware/default.asp or http://web.mit.edu/network/pgp.html. According to its inventor, Phil Zimmerman, "PGP is a program that gives your electronic mail something that it otherwise doesn't have: Privacy. It does this by encrypting your mail so that nobody but the intended person can read it. When encrypted, the message looks like a meaningless jumble of random characters. PGP has proven itself quite capable of resisting even the most sophisticated forms of analysis aimed at reading the encrypted text." How does PGP work? Bob wants to send Alice a love letter. They don't want Eve to see it. Eve, however, is a brilliant hacker who can break into Alice's or Bob's email. Nevertheless, Bob can keep Eve from reading his love letter by encrypting it. How can Alice read this scrambled message? She gives Bob her "public PGP key." His PGP program uses it to encrypt email to her. Then only Alice, using a PGP program, her "private PGP key" plus her passphrase (kind of like a password), can decrypt the love letter.
Figure 7 shows a message about to be encrypted. (What you see will depend on which PGP program you use and which email program.) Christopher J. Rouland will be the only one able to decrypt it. You can encrypt a message with keys from two or more people. All whose keys are used will be able to decrypt it. |
|
|
|
