An early draft of a paper based on my comments at the Crypto '95 rump session is available at: http://www.communities.com/paper/agnostic.html Here's the abstract: Abstract: One of the unique aspects of Chaum's blind signature scheme for anonymous transactions is that it is practiced entirely by the side that wants to be anonymous. In a customer-bank relationship, the customer's software practices the technology, not the bank's. Chaum's patent on blind signatures cites as prior art a non-anonymous signature scheme that differs significantly only in steps taken by the "customer" side. An open standard for electronic cash would then allow a bank or other cash issuer to remain agnostic with respect to customer's software blinding or not blinding. Since the bank's software would be practicing technology cited as prior art by Chaum in his patent, and would have a substantial non-infringing use, I argue that the bank would not need to license Chaum's patents, provided the bank itself only provided non-blinding customer software. Here's a review of the talk by Hal Finney... :-) One of the more interesting talks I thought was from cypherpunk Doug Barnes, on "identity agnostic" electronic cash. This is basically an idea for creating a Magic-Money-type electronic cash server without violating Chaum's cash patent. What you do is to run the server and publish a spec it will follow. All the server does is do an RSA signature on the raw data it receives and decrement the user's account accordingly. The user has a choice of doing blinding or not on the signature. Chaum's patent covers the blinding, so if the user wants to do that he should be sure to license the patent or live somewhere it doesn't apply (or ignore it if he figures he's too small potatoes for them to care about). But the server isn't responsible for checking all this. It just does RSA sigs, which is prior art as far as Chaum's patent goes. Users can blind or not, it doesn't care. It is "identity agnostic" as Doug says. The implication is that with an RSA license you could run this kind of bank (online cash) and ignore Chaum's patents, while a horde of end users violate the patents but take safety in numbers and get anonymity. Lawyers like to go after big targets but the servers aren't violating anything.