crypt(1)                                                    crypt(1)


       NAME
             crypt - encode/decode

       SYNOPSIS
             crypt [password]
             crypt [-k]

       DESCRIPTION
             crypt reads from the standard input and writes on the standard
             output.  The password is a key that selects a particular
             transformation.  If no argument is given, crypt demands a key
             from the terminal and turns off printing while the key is
             being typed in.  If the -k option is used, crypt will use the
             key assigned to the environment variable CrYpTkEy.  crypt
             encrypts and decrypts with the same key:

                   crypt key < clear > cypher
                   crypt key < cypher | pr

             Files encrypted by crypt are compatible with those treated by
             the editors ed(1), edit(1), ex(1), and vi(1) in encryption
             mode.

             The security of encrypted files depends on three factors: the
             fundamental method must be hard to solve; direct search of the
             key space must be infeasible; ``sneak paths'' by which keys or
             clear text can become visible must be minimized.

             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 known, but not widely; moreover
             the amount of work required is likely to be large.

             The transformation of a key into the internal settings of the
             machine is deliberately designed to be expensive, that is, to
             take a substantial fraction of a second to compute.  However,
             if keys are restricted to (say) three lower-case letters, then
             encrypted files can be read by expending only a substantial
             fraction of five minutes of machine time.

             If the key is an argument to the crypt command, it is
             potentially visible to users executing ps(1) or a derivative.
             The choice of keys and key security are the most vulnerable
             aspect of crypt.




                           Copyright 1994 Novell, Inc.               Page 1

      crypt(1)                                                    crypt(1)


      FILES
            /dev/tty  for typed key

      REFERENCES
            ed(1), edit(1), ex(1), makekey(1), nroff(1BSD), pg(1), ps(1),
            stty(1), vi(1)

      NOTICES
            This command is provided with the Encryption Utilities, which
            is only available in the United States.  If two or more files
            encrypted with the same key are concatenated and an attempt is
            made to decrypt the result, only the contents of the first of
            the original files will be decrypted correctly.

            If output is piped to nroff and the encryption key is not
            given on the command line then do not pipe crypt through pg(1)
            or any other program that changes the tty settings.  Doing so
            may cause crypt to leave terminal modes in a strange state
            [see stty(1)].





























                          Copyright 1994 Novell, Inc.               Page 2