By "proxy" I didn't necessarily mean "web proxy". If at any point an IP address is visible it is feasible to exclude transactions that involve US IP addresses. This is, of course, trivial to circumvent - which was my point.
You're not speaking to the important question, which is whether there is any way for the recipient to tell the originating IP of a bitcoin transaction. I am gathering the answer is "no". If "yes", then there is an obvious place to put the IP restrictions: in the satoshi dice service itself. Obviously, even in this case, it could be defeated with a proxy.
> You're not speaking to the important question, which is whether there is any way for the recipient to tell the originating IP of a bitcoin transaction. I am gathering the answer is "no".
Correct. There is absolutely no way whatsoever to determine the originating IP address of a bitcoin transaction, short of global network surveillance.
The point is that the recipient of the money doesn't interact at all to receive it; the rest of the network just "decides" (based on the transaction) that such address now has X more coins. The machine with the address/wallet is not consulted.
That is not the point. The information could be available, and the recipient could therefore act on it. If the information is not available then that is the point - but that could in principle be the case even if there was interaction.
