Author: David A. Harding 2020-06-19 20:52:20
Published on: 2020-06-19T20:52:20+00:00
In a Bitcoin-dev email thread, David A. Harding clarifies some misunderstandings regarding a proposed attack on Lightning Network channels. The attack would involve an attacker broadcasting the latest state of a channel and causing the honest counterparty to send funds to the attacker's address by exploiting a time-lock loophole. Harding notes that the honest counterparty would only need to send one blind child to resolve the issue, but the transaction would only be relayed by a Bitcoin peer if they also have the parent transaction. In this case, the honest user can use `getdata('tx', $txid)` to retrieve the preimage and resolve the HTLC with the upstream channel.Harding revises his previous conclusion, stating that the strongman argument for the attack is that the attacker will be able to perform a targeted relay of the low-feerate preimage-containing transaction to miners, while everyone else on the network will receive the honest user's higher-feerate expired-timelock transaction. He adds that unless the honest user has a connection to a miner's node, they will not be able to CPFP fee bump or use getdata to retrieve the preimage.
Updated on: 2023-06-03T00:48:25.722340+00:00