is an exact implementation of Boris Hagelin's
cryptographic machine called the M-209 by the U. S. Army [1].
reads from the standard input file and writes
It is thus suitable for use as a filter.
For a given password, the encryption
.bd " crypt znorkle <clear >cypher"
.bd " crypt znorkle <cypher"
[1] U. S. Patent 2,089,603.