=over

=item crypt PLAINTEXT,SALT

Encrypts a string exactly like the crypt(3) function in the C library
(assuming that you actually have a version there that has not been
extirpated as a potential munition).  This can prove useful for checking
the password file for lousy passwords, amongst other things.  Only the
guys wearing white hats should do this.

Note that C<crypt()> is intended to be a one-way function, much like breaking
eggs to make an omelette.  There is no (known) corresponding decrypt
function.  As a result, this function isn't all that useful for
cryptography.  (For that, see your nearby CPAN mirror.)

Here's an example that makes sure that whoever runs this program knows
their own password:

    $pwd = (getpwuid($<))[1];
    $salt = substr($pwd, 0, 2);

    system "stty -echo";
    print "Password: ";
    chop($word = <STDIN>);
    print "\n";
    system "stty echo";

    if (crypt($word, $salt) ne $pwd) {
	die "Sorry...\n";
    } else {
	print "ok\n";
    }

Of course, typing in your own password to whoever asks you
for it is unwise.

=back