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Comment by MichaelGG | Hacker News Reader

Can you explain how they blocked US players? I skimmed that page and only saw "not possible since you play via sending to a bitcoin address; there's no IP to block".

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Sorry for the confusion. They blocked US players from their website where they could get information on what was currently being bet on and where to send their Bitcoin.

IIRC Satoshi Dice worked by sending Bitcoin to a specific address for a bet and the address changed each time which they displayed on their website. By blocking US players from the website they could legally claim to be in compliance with the regulation (IANAL).

Hmm the site seems to load the same for me US IP or not. You do have to click "I agree" that you're legal, though.

Well some months ago it was a separate landing page, but I guess they changed it. They still don't display the information unless you agree that you are in a legal jurisdiction to use the service.

Presumably they blocked US players who don't know how to use a proxy?

Can you explain further? Playing is literally done only by sending to a Bitcoin address. You win or lose and get paid back or not. There's no website involved in the actual game.

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.

Bitcoin is a decentralized system, so there is no reasonable place to put these IP restrictions.

If there is a single Bitcoin mining node (out of thousands[0]) that will accept your transaction, you can play.

[0] http://blockchain.info/connected-nodes

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.

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.

But it's not like the recipient could invalidate the transaction even if it had that information.

No, but it could either return it or pocket it, rather than letting them play.

> 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.

I believe all they did was block US users from seeing the website - there is no way to block users from transacting with Satoshidice.

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