PGP: The key to your heart

huey% pgp message.pgp 

Don't try to view the encrypted file with an editor or
more, since it is a binary file that will at the least
wreak havoc with your keyboard driver. Be sure to remove the original,
plain text version of the file (or have PGP do it for you using the
-w option), or your encryption efforts are for naught.
The conventional encryption feature of PGP makes it possible to
standardize on PGP for all of your data-security tasks.

Let's actually swap secret bits with someone. Hand PGP the options
-eat and the recipients' user ID (we'll send this to our
buddy Pepe):

heuy% pgp -eat message pepe
Recipients' public key(s) will be used to encrypt. 
Key for user ID: Pepe <pepe@unixinsider.com>
1024-bit key, Key ID 13FAC021, created 1995/05/17
.
Transport armor file: message.asc

We'll come back to the user ID, and how it relates to a recipient and
his or her key shortly. The options produce a message suitable for
mailing:

• Encryption is turned on with the -e option.
  
• The -a flag tells PGP to produce an ASCII output
  file. Most mailers can't handle a binary file, so use the ASCII option
  to perform the equivalent of a uuencode. In PGP-speak,
  the ASCII output is called an ASCII armor file or a transport armor
  file, and is given the .asc extension.
  
• PGP treats the message like a text file when the -t
  option is given. When this file is decrypted on a Macintosh or
  Windows/DOS machine, it will have the correct end of line characters
  inserted. Unless you're specifically encrypting a binary file (such as
  a data set), use the -t option to preserve your end-of-line
  boundaries.
  

Now that we have message.asc, we can simply drop it in the
mail to Pepe:

heuy% mail pepe@unixinsider.com < message.asc

Very few people compose mail in a text file and then pipe it to mail.
PGP's filter option (-f) makes it easier to combine
the encryption and composition steps: