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I'm no crypto expert, but just thinking this through: In Diplomacy, all that's required is that you commit to your orders before seeing anyone else's; once eve
by avibryant 17y ago
I'm no crypto expert, but just thinking this through:
In Diplomacy, all that's required is that you commit to your orders before seeing anyone else's; once everyone has committed, all the orders are revealed.
What if, for every turn, every player:
1. Generates a new key
2. Uses this key to produce an HMAC of their orders
3. Publishes the HMAC
4. (once everyone has published the HMAC) Publishes their orders
5. Publishes their key so that everyone can verify the HMAC
Would it be feasible for someone to generate two alternative sets of orders that - given different, carefully chosen keys - produced the same HMAC, and then choose which combination of orders and key to publish based on what other moves are revealed? If so, is there some kind of limitation that could be placed on acceptable keys that would prevent this without allowing the hash to be brute forced?
- eru 17y agoYou are basically right. In Diplomacy you need to commit to some secret bits, and after everyone has committed, reveal them. But what if I refuse to do step 5? What if I accidentally forgot my key (and the orders)? Should my units just halt, as if I had not handed in any orders?
- avibryant 17y agoYes, there are specific rules in Diplomacy for handling the case where someone doesn't fully or properly submit their orders - eventually your units go into "Civil Disorder". It's not a problem.
- eru 17y ago(Sorry, can't reply to your comment directly, yet.) The problem is, that you do not want give people the option to decide between using their orders or going into Civil Disorder (by not revealing their keys). Especially after they've seen the other player's orders.
- avibryant 17y agoGood point, though going into Civil Disorder is leaving the game - I guess this would let them leave it on their terms, possibly screwing over one of the remaining players in favor of another, but that doesn't strike me as that big a weakness.