crypt(1)                         DG/UX 5.4.2                        crypt(1)


NAME
       crypt - encode/decode

SYNOPSIS
       crypt [ password ]

   where:
       password  A key that selects a particular transformation

DESCRIPTION
       Crypt, although documented here, is not distributed outside of the
       United States in accordance with Federal Export regulations.
       International versions of the DG/UX System do not include encryption
       mechanisms.  crypt reads from the standard input and writes on the
       standard output.  If no password is given, crypt demands a key from
       the terminal and turns off printing while the key is being typed in.
       crypt encrypts and decrypts with the same key:

              crypt password <clear >cypher

              crypt password <cypher | pr

       will print the clear.

       Files encrypted by crypt are compatible with those treated by the
       editor ed 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; and "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, they require a lot
       of work.

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

       Since 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.


EXAMPLES
       $ cat aname
       Don Ho
       $ crypt 24 < aname > encryptedname




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crypt(1)                         DG/UX 5.4.2                        crypt(1)


       Crypt is passed a key and a file that contains a name to be
       encrypted.  crypt puts the encrypted name into the file
       encrypted_name.

       $ crypt 24 < encryptedname
       Don Ho

       Crypt decrypts the contents of the encrypted file and displays the
       decrypted results on the screen.

FILES
       /dev/tty  For typed key

SEE ALSO
       ed(1), makekey(1), stty(1).

NOTES
       If output is piped to nroff and the encryption key is not given on
       the command line, crypt can leave terminal modes in a strange state
       (see stty(1)).
       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.


































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