Eltoo uses the no-penalty submission mechanism, where the cost for an adversary to submit an old state is the transaction fee. This action seems unprofitable, but if we add HTLC to Eltoo, things seem different.

One effect of submitting the old state is delaying the channel settlement. For example, Alice and Bob have an Eltoo channel and the challenge period is 10 blocks. Then, they both intend to close the channel at the block height 100. The difference is that Alice commits the latest state while Bob commits an old one. Suppose Bob's transaction is included in the latest block. Then, Bob continues to compete with Alice for the right to submission and Alice failed to commit the latest state until the block height is 120. At this point, the channel settlement time is delayed from 100 + 10 = 110 to 120 + 10 = 130. If there is an HTLC in the channel with an expiration time of 120, then the adversary's delay changes the attribution of this HTLC. I'm curious if Eltoo will be exploited by the above actions?

  • I am not sure I understand your question. Why is the blockheight suddenly 120? If Bob gets his old update tx in Alice can immediately prevent Bob from getting his settlement in by getting a newer update tx in (already in block 101) May 5 at 7:58
  • Sorry for the misleading, I need to clarify two points 1. Assuming the latest status is 10, then Bob will start committing from 2. If his transaction is successful, then he will submit 3 next (challenging himself). 2. I'm not sure it's a reasonable assumption that Alice would be able to submit the update tx immediately, I think in a worse case scenario maybe she would need two to three blocks to submit her transaction? (correct me if I'm wrong). A delay of 20 blocks may be an exaggeration, but I'm just curious if this malicious delay affects the correct settlement of HTLC?
    – sphpmp
    May 5 at 8:13


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