use Math::TrulyRandom;
my $seed = truly_random_value();
srand($seed);
my $randbytes = join("",map {int(rand(10))} (0..16));
my $challenge = join(".",time,$$,$randbytes);

##</code><code>##

use Digest::MD5 qw(md5_base64);
$digest = md5_base64($challenge.$password);