crypt(1)						      General Commands Manual							  crypt(1)

NAME

       crypt - encode and decode files

SYNOPSIS

       [password]

DESCRIPTION

       reads  from the standard input and writes on the standard output.  password is a key that selects a particular transformation.  If no pass-
       word is given, demands a key from the terminal and turns off printing while the key is being typed in.  encrypts and decrypts with the same
       key:

       The latter command decrypts the file and prints the clear version.

       Files encrypted by are compatible with those treated by the editor in encryption mode (see ed(1)).

       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.

       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 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 substan-
       tial fraction of a second to compute.  However, if keys are restricted to, for example, 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 command, it is potentially visible to users executing the or a derivative (see ps(1)).  The choice of
       keys and key security are the most vulnerable aspect of

EXAMPLES

       The following example demonstrates the use of to edit a file that the user wants to keep strictly confidential:

	      ...
	      ...
	      ...

       Note that the option is the encryption mode of and prompts the user for the same key with which the file was encrypted.

WARNINGS

       If output is piped to and the encryption key is given on the command line, can leave terminal modes in a strange state  (see  nroff(1)  and
       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 the first of the
       original files is decrypted correctly.

FILES

       for typed key

SEE ALSO

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

																	  crypt(1)