NAME
    Crypt::CVS - Substitution cipher for CVS passwords

SYNOPSIS
        use CVS::Password qw(:all);

        # AE00uy
        my $scrambled = scramble "foobar";
        # foobar
        my $descrambled = descramble $scrambled;

DESCRIPTION
    The CVS protocol uses a substitution cipher for passwords going over the
    wire. From src/scramble.c in GNU CVS's source distribution:

        Trivially encode strings to protect them from innocent eyes (i.e.,
        inadvertent password compromises, like a network administrator
        who's watching packets for legitimate reasons and accidentally sees
        the password protocol go by.

    About the encoding:

        Map characters to each other randomly and symmetrically, A <--> B.

        We divide the ASCII character set into 3 domains: control chars (0
        thru 31), printing chars (32 through 126), and "meta"-chars (127
        through 255).  The control chars map _to_ themselves, the printing
        chars map _among_ themselves, and the meta chars map _among_
        themselves.  Why is this thus?

        No character in any of these domains maps to a character in another
        domain, because I'm not sure what characters are valid in
        passwords, or what tools people are likely to use to cut and paste
        them.  It seems prudent not to introduce control or meta chars,
        unless the user introduced them first.  And having the control
        chars all map to themselves insures that newline and
        carriage-return are safely handled.

FUNCTIONS
scramble($plaintext)
    Takes plaintext and returns a scrambled version of it. The first byte of
    the scrambled string is a single letter indicating the scrambling
    method. This has always been "A", it's very unlikely that there'll ever
    be another scrambling method.

unscramble($scrambled)
    Takes a scrambled string and returns an unscrambled version. Dies if the
    first letter isn't "A".

EXPORTS
    The functions "scramble" and "descramble" can be optionally exported.
    "use Crypt::CVS ':all'" exports both of them.

AUTHOR
    Ævar Arnfjörð Bjarmason <avar@cpan.org>

LICENSE
    Copyright 2007-2010 Ævar Arnfjörð Bjarmason.

    This program is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.

