Path: utzoo!mnetor!uunet!husc6!bloom-beacon!gatech!purdue!umd5!brl-adm!brl-smoke!gwyn
From: gwyn@brl-smoke.ARPA (Doug Gwyn )
Newsgroups: sci.crypt
Subject: Re: One time pads?
Message-ID: <7253@brl-smoke.ARPA>
Date: 12 Feb 88 06:38:19 GMT
References: <4209@june.cs.washington.edu>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 16

In article <4209@june.cs.washington.edu> randy@june.cs.washington.edu (William Randy Day) writes:
>I'd like to know what a one time pad is.

This is described in David Kahn's "The Codebreakers", which is "must"
reading (find the hardback, which was a best seller, rather than the
abridged paperback, which omitted a lot of interesting technical stuff,
presumably on the theory that the American reading public is stupid).

The general idea is that encryption is performed using a truly random
key stream, which both parties have a copy of, and as the key stream
is used, it is destroyed (as opposed to eventually being re-used).
There are several variations on this theme, but this is the essence.

The "one-time pad" method gets its name from the small pads containing
keys that spies (particularly Soviet agents) would use.  As a sheet
was used, it was torn off and destroyed (presumably by burning).