rich1.0npub1wtx5qvewc7pd6znlvwktq03mdld05mv3h5dkzfwd3dc30gdmsptsugtuynhttps://nostr.ae/npub1wtx5qvewc7pd6znlvwktq03mdld05mv3h5dkzfwd3dc30gdmsptsugtuynnjumphttps://nostr.ae📅 Original date posted:2020-10-13 📝 Original message: Joost Jager <joost.jager at gmail.com> writes: >> The LOW-REP node being out of pocket is the clue here: if one party >> loses funds, even a tiny bit, another party gains some funds. In this >> case the HIGH-REP node collaborating with the ATTACKER can extract some >> funds from the intermediate node, allowing them to dime their way to all >> of LOW-REP's funds. If an attack results in even a tiny loss for an >> intermediary and can be repeated, the intermediary's funds can be >> syphoned by an attacker. >> > > The assumption is that HIGH-REP nodes won't do this :) LOW-REP will see all > those failed payments and small losses and start to realize that something > strange is happening. I know the proposal isn't fully trustless, but I > think it can work in practice. > > >> Another attack that is a spin on ZmnSCPxj's waiting to backpropagate the >> preimage is even worse: >> >> - Attacker node `A` charging hold fees receives HTLC from victim `V` >> - `A` does not forward the HTLC, but starts charging hold fees >> - Just before the timeout for the HTLC would force us to settle onchain >> `A` just removes the HTLC without forwarding it or he can try to >> forward at the last moment, potentially blaming someone else for its >> failure to complete >> >> This results in `A` extracting the maximum hold fee from `V`, without >> the downstream hold fees cutting into their profits. By forwarding as >> late as possible `A` can cause a downstream failure and look innocent, >> and the overall payment has the worst possible outcome: we waited an >> eternity for what turns out to be a failed attempt. >> > > The idea is that an attacker node is untrusted and won't be able to charge > hold fees. The attacker controls both the sender and the HIGH-REP node. The sender doesn't need to be trusted, it just initiates a payment that is used to extract hold fees from a forwarding node. The HIGH-REP node doesn't lose reputation because from what we can witness externally the payment failed somewhere downstream. It does require an attacker to have a hold fee charging HIGH-REP node, yes, but he is not jeopardizing its reputation by having it fail downstream. Cheers, Christian