I've read before that the overall strength of Filevault encryption is to some extent dependent on the complexity of password you use. So I tend to use a pretty robust password when I'm encrypting a drive. Whenever I did this in the past I tended to have a few user accounts, but this time 'round I did a fresh install of Yosemite and just had an admin account. I notice that the admin/default account, if there is only one (which I set up with a simpler password) automatically has rights to unlock Filevault at boot time. Does anyone have a (hopefully learned) view on whether this compromises FileVault security?