I wrote Reasonably Adequate Privacy in 1996 as a gift for my manager, Nat Howard, on his birthday. Nat is very interested in cryptography and uses Phil Zimmermann's Pretty Good Privacy quite a bit.
His wife, Marta, had arranged a birthday party, and suggested that if we were to bring gifts they should cost less than five dollars. I wrote RAP, then printed it and packaged it in an old shoebox along with a lemon, a box of toothpicks, and several sheets of paper labeled "Message Substrates." Total cost (not including the shoebox, which I found in my closet, and the "Message Substrates") was under a dollar -- 21¢ for the lemon and 59¢ for the toothpicks.
The result was a hit at the party so I decided to reformat it as HTML and post it on the web.
I hope you enjoy reading it as much as I enjoyed writing it!