opendarwin man page for crypt

crypt(1)																  crypt(1)

NAME
       crypt - encode or decode a file

SYNOPSIS
       crypt [password]

       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 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. crypt encrypts and decrypts with the same key:

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

       prints 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 substan-
       tial 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.

       /dev/tty        for typed key

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsu			   |
       +-----------------------------+-----------------------------+

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

								    8 Mar 2005								  crypt(1)