crypt(1)              UNIX System V(Encryption Utilities)              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.

FILES
      /dev/tty  for typed key

SEE ALSO
      ed(1), edit(1), ex(1), makekey(1), nroff(1), pg(1), ps(1), stty(1), vi(1)

NOTES
      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


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crypt(1)              UNIX System V(Encryption Utilities)              crypt(1)


      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)].
















































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