The Internet is a great medium for keeping in touch with one another, but it is also inherently insecure. In other words, a clever snoop can eavesdrop on your communications if you don't take precautions. E-mail is particularly vulnerable, but fortunately, there is an easy solution.
Back in the early 1970's, the technique of public key cryptography was invented, and now it is easily available to you through Pretty Good Privacy, or PGP. Public key cryptography is based on my having two keys: a public key that I make available to the world, and a private key that I keep secret. Anyone who wishes to send me private e-mail, has an e-mail program that can understand PGP, and has my PGP public key, can encrypt the message and send it to me in the knowledge that it won't be read by anyone else as it travels across the Net. Another nice feature is that I can digitally sign any e-mail I send to you using my private key and you can verify that it did, in fact, come from me.
Once you get the PGP software installed and running, you'll then need to download my public key.
|My email@example.com public key
EA2C 43E3 C408 D755 3803 26D8 CE88 71B3
Once you get started, you can look up anyone's PGP public key on MIT's public key server.