Custom Fields – used for search, but hidden on signup form

Hi,

I want to use a custom field called “Not Verified” and “Verified”. When a customer signs up, this is hidden from the end user in the form, but when account created it defaults to “Not Verified”. A few weeks later, I want to go in as admin and set that custom field to “Verified”.

Out on the main site, listings are always shown immediately, but I want site visitors to be able to filter/search for “Verified” and “Not Verified” listings.

Is something like this possible? I though about simply hiding the field with CSS on the signup page with display:none, but that could be bypassed easily.

Thanks!
Aengus