#!perl -w
# decrypt_users_and_groups2.plx - decrypt Users & Groups passwords
# by Chris Nandor, pudge@pobox.com, http://pudge.net/
# Wednesday, July 14, 1999 - Friday, July 16, 1999

# usage: decrypt [file] [user1 user2 ...]
#   file will be looked for if not provided and using MacPerl
#   program will prompt for users if not provided

use POSIX qw(O_RDONLY isprint);
use strict;

my($file, @users, $text, @k);

# get file if not supplied
unless ($file = shift) {
    eval {require 'Mac/Files.pm'};
    die $@ if $@;
    Mac::Files->import;
    $file = FindFolder(&kOnSystemDisk, &kPreferencesFolderType) .
        ':Users & Groups Data File';
}

unless (@users = @ARGV) {
    print "Type a list of users.  Hit ctrl-D to finish.\n";
    chomp(@users = <STDIN>);
}

@k = map ord, qw(s p c g t p r k);
sysopen F, $file, O_RDONLY or die "Can't open `$file': $!";
binmode F;
read F, $text, -s $file;

for my $u (sort @users) {
    my $found;
    my $nu = $u;
    $nu .= "\000" unless length($nu) % 2;

    MAIN: while ($text =~ /\Q$nu\E(.{8})(.{4})/gs) {
        my $i = vec($2, 0, 32);
        my(@b, $p) = unpack 'C*', $1;
        next if $b[0] == 0;

        for my $n (0 .. $#b) {
            my $b = $b[$n] ^ ($n == 0 ? $i ^ 1 : $b[$n-1]) ^ $k[$n];
            my $c = chr $b;
            next MAIN if $b != 0 &&! isprint $c;
            $p .= $c;
        }
        $p =~ s/\000+$//;
        printf "%-31.31s (%4d): $p\n", $u, $i, $p;
        $found++;
    }
    printf "%-31.31s (    ): no password found\n", $u unless $found;
}

__END__