crypt(1)

NAME

     crypt - encode or decode a file

SYNOPSIS

     crypt [password]

DESCRIPTION

     The crypt utility encrypts and decrypts the  contents  of  a
     file.  crypt reads from the standard input and writes on the
     standard output. The password is a key that selects  a  par-
     ticular  transformation.  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:

     example% crypt key<clear.file> encrypted.file
     example% crypt key<encrypted.file | pr

     will print the contents of clear.file.

     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

ATTRIBUTES

     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Availability                | SUNWcsu                     |
    |_____________________________|_____________________________|

SEE ALSO

     des(1), ed(1), ex(1), makekey(1), ps(1),  vi(1),  attributes
     (5)