DOS's against makers about joinmarket

[chris-belcher]

Actually one resource of the maker's that a DOSer could use up is position in the HD wallet. If a DOSer partially fills a maker's order it will cause the maker to get another address from it's wallet. Do this a couple of times and the next address pointer will go beyond the gap limit. Do a real coinjoin and coins will be moved beyond the gap limit.

Then when the operator of the maker queries the balance of the wallet, it will appear as if they lost coins. The worst this attack can do is scare the operator a little, they would check their logs and set their gap limit to the required number to reach their coins.

[chris-belcher]

An obvious solution is to store the HD key pointer in the wallet file. Restoring the wallet from seed may not find these keys but there could be an added message to try increasing the gap limit (or max mix depth) if the user believes coins have gone missing.

[chris-belcher]

wallet file now stores the index of the HD wallet b3dc7c7 closing this dos opportunity

[chris-belcher]

Another obvious DOS method is that the taker can create transactions that take a long time, or never get mined into a block. For example by the change address having size 1 satoshi.

Makers could check for simple non-standard transactions but they'd also need a timeout for waiting for their UTXOs to confirm. Perhaps even a timeout related to how much in fees they're earning for that transaction.