Comment 4 for bug 1285247

Hrmmmm... This exists since 2014 !!??
And it's not solved yet (2016)?

Please also see:
https://ubuntuforums.org/showthread.php?t=2330425&page=2&p=13549951#post13549951
and
https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1602155

@Patrik: better yet is to use "shred", it's faster than urandom.