#! /usr/bin/perl

use strict;
use warnings;

sub rnd_bytes {
    local $/ = \( shift || 8 );
    open my $fh, '<', '/dev/urandom';
    scalar <$fh>
}

for my $n (unpack "Q*", rnd_bytes(20 * 8)) {
        printf "\r%064b %016X\n",$n,$n;
}