Rabbinically approved Torah marking

Schneier has a very interesting bit on marking and registering your Torah without violating Jewish law:

"According to Jewish law, Torahs must be identical. When you make a copy, you cannot change or add a single character. That means you can't write 'Property of....' You can't add a serial number. You can't make any kind of identifying marks. This turns out to be a problem when Torahs are stolen; it's impossible to identify that they're stolen goods. Now there's a method of identifying Torahs without violating Jewish law..."