Since the key is an argument to the  crypt  command,  it  is
     potentially visible to users executing ps(1) or a derivative
     command.  To minimize this possibility, crypt takes care  to
     destroy  any  record  of the key immediately upon entry.  No
     doubt the choice of keys  and  key  security  are  the  most
     vulnerable aspect of crypt.


##</code><code>##

     crypt implements a  one-rotor  machine  designed  along  the
     lines  of  the  German Enigma, but with a 256-element rotor.
     Methods of attack on such machines are  widely  known,  thus
     crypt provides minimal security.