Comment 3 for bug 1573974

The "hanging" behavior seems to be happening because makepasswd reads from /dev/random. A workaround is to mash keys or move the mouse to generate entropy. This only works if you have physical access to the machine. It doesn't work if you're logged in via SSH.

The man page for makepasswd advertises that makepasswd uses /dev/urandom. I believe/assume that this was the behavior in 14.04, since I've only had this problem in 16.04. I'd like to suggest changing it back to /dev/urandom.