I strongly recommend that anyone considering licensing from Chaum first read my paper on some interesting aspects of his basic blinding patent. The paper is at: http://www.communities.com/paper/agnostic.html. I will be putting up another short paper on anonymous currency management within the next few days. Also, I strongly recommend that anyone serious about this not use the word "bank", and take the time to figure out how to structure the service as an NBFI (non-banking financial institution) and not a "bank". Note that NBFIs are still regulated, and you will, at minimum, need to consult with your state banking regulators as well as the IRS (who also regulate money transmitters, i.e. issuers of traveller's checks, moneygrams, etc.) Note that the BSA (Bank _non_ Secrecy Act) does in fact apply to NBFIs and money transmitters, and you should be sure to educate yourself as to the implications of this. I will be covering some aspects of these issues at length in my trip report on the anti-money-laundering conference I recently attended, which was a real eye-opener in a number of ways.