In terms of the ad concern, through our choices we have already made that inconvenient to do. At the moment we do hold the encryption keys, but as privacy seems to be a great concern (as we expected it to be) we will continue to push forward our practices on privacy.

So to be clear, anything you share on Circles is encrypted in transit with SSL/TLS, then encrypted at rest on our servers, to which we currently (but hopefully not for long) hold the keys.