Open kristovatlas opened 8 years ago
Summary of attack: A Protocol peer
or Network observer
attacker can observe a transaction broadcast to the network and tie the input(s) to the first hop IP address observed.
I can't find any applicable attacks under these two attacker categories. In the last version of the threat model, this attack worked:
"Link addresses belonging to a single user by observing source IP address for first relay of transactions"
However, I think that may have been reworded since, such that it no longer applies:
Link addresses belonging to a single user by observing that multiple transactions enter the network from an origin point likely to belong to a single user.
Here's a proposed wording for a new attack under the Network observer
category:
Link a transaction's input address(es) to a specific IP address by observing the first relay of a broadcasted transaction.
Yes, there is no such thing as an "input address," but the meaning is clear enough. I'm happy to rephrase if it does not get too wordy.
I think this should be in the Network observer
category instead of Protocol peer
because it could also apply to a thin client such as a web wallet prior to reaching the Bitcoin P2P network.
The existing countermeasure that falls under the Blockchain observer
attacker category is relevant:
Use mixing when sending transactions, and make non-mixed transactions resemble mixed transactions
This existing countermeasure also applies:
Route outgoing transactions via a method that does not reveal the IP address of the sender
The same four criteria for OBPPV3/CM11 in the blockchain observer can be used here:
Existing attack: "Link addresses belonging to a single user by observing source IP address for first relay of transactions"
By using CoinJoin or creating a transaction indistinguishable from a CoinJoin, a network attacker who is not a transaction participant has weakened certainty that an address in the inputs belongs to IP address observed as a first hop. From An Analysis of Anonymity in Bitcoin Using P2P Network Traffic: