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NAME    [Toc]    [Back]

       crypt - encode/decode

SYNOPSIS    [Toc]    [Back]

       crypt key < input.File > output.File

DESCRIPTION    [Toc]    [Back]

       The crypt command reads from the standard input and writes
       on the standard  output.  You  must  supply  a  key  which
       selects  a  particular  transformation.  If no password is
       given, crypt demands a key from the terminal and turns off
       printing  while  the key is being typed in. The crypt command
 encrypts and decrypts with the same key.

       Files encrypted by crypt are compatible with those treated
       by the ed, ex and vi editors 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.

       The  crypt command 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,  for
       example,  to  take  a  substantial fraction of a second to
       compute. However, if keys are restricted to  three  lowercase
  letters, then encrypted files can be read by expending
 only a substantial fraction of five minutes of machine

       Since  the key you choose is an argument to the crypt command,
 it is potentially visible to users executing the  ps
       command  or  a  derivative.  To minimize this possibility,
       crypt destroys any record  of  the  key  immediately  upon
       entry.  The  most vulnerable aspect of crypt is the choice
       of keys and key security.

EXAMPLES    [Toc]    [Back]

       The following examples use KEY as the key to  encrypt  and
       decrypt   files.  The  first  example  encrypts  the  file
       plain.File,   naming   the   resulting   encrypted    file
       crypt.File.   The   second   example   decrypts  the  file
       crypt.File,   naming   the   resulting   decrypted    file
       decrypt.File.  The third example prints the encrypted file
       in clear text.  $ crypt KEY < plain.File > crypt.File

       $ crypt KEY < crypt.File > decrypt.File

       $ crypt KEY < crypt.File | pr

FILES    [Toc]    [Back]

       for typed key

SEE ALSO    [Toc]    [Back]

       Commands: ed(1), ex(1), vi(1), makekey(8)

       Functions: crypt(3)

[ Back ]
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