


CRYPT(1)                 USER COMMANDS                   CRYPT(1)



NAME
     crypt - encode or decode a file

SYNOPSIS
     crypt [ _p_a_s_s_w_o_r_d ]

DESCRIPTION
     crypt encrypts and decrypts the contents of a  file.   crypt
     reads  from  the  standard  input and writes on the standard
     output.  The _p_a_s_s_w_o_r_d is a key  that  selects  a  particular
     transformation.   If  no  _p_a_s_s_w_o_r_d 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:

          example% crypt key <_c_l_e_a_r._f_i_l_e >_e_n_c_r_y_p_t_e_d._f_i_l_e
          example% crypt key <_e_n_c_r_y_p_t_e_d._f_i_l_e | pr

     will print the contents of _c_l_e_a_r._f_i_l_e.

     Files encrypted by crypt are compatible with  those  treated
     by the editors ed(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 cleartext 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  widely  known,  thus
     crypt provides minimal security.

     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.

     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.

FILES
     /dev/tty            for typed key

SEE ALSO
     des(1), ed(1), ex(1), ps(1), vi(1), makekey(8)



Sun Release 4.1   Last change: 9 September 1987                 1






CRYPT(1)                 USER COMMANDS                   CRYPT(1)



RESTRICTIONS
     This program is not available on  software  shipped  outside
     the U.S.




















































Sun Release 4.1   Last change: 9 September 1987                 2



