Author: ZmnSCPxj 2020-07-02 16:06:04
Published on: 2020-07-02T16:06:04+00:00
The article proposes a gradual scorched-earth policy to mitigate an attack on Bitcoin's mempool. The strategy involves Alice starting at the 1% reserve and gradually increasing fees for every block that goes by until she settles at an (f-x)/(b-x) level that achieves the least weak miner known to run the myopic strategy.The MAD-HTLC argument, which applies to off-chain transactions, also applies to channel mechanisms themselves. The article describes various channel mechanisms such as Spilman, Poon-Dryja, Decker-Wattenhofer decrementing-nSequence, and Decker-Russell-Osuntokun mechanisms and how they are affected by MAD-HTLC. Additionally, the author suggests that other proposed systems such as CoinPools, channel factories, and state chains are also vulnerable to the MAD-HTLC argument. The Decker-Russell-Osuntokun (DRO) protocol uses a relative locktime to ensure confirmability of update branches indefinitely. Update transactions misuse nLockTime as a sequence number. The first update transaction has the lowest nLockTime, with each succeeding update transaction having a higher value until it reaches the present time. Update transactions are signed with SIGHASH_NOINPUT, allowing them to not only spend the funding outpoint but also any previous update transaction. This feature enables a newer update transaction to re-spend an older one before the state transaction can be confirmed.Under the MAD-HTLC argument, participants who prefer an older state can publish the update transaction for the older state and bribe miners to defer confirmation of newer update transactions until the state transaction for that update is confirmed. However, this argument relies on the assumption that "a transaction, that can be confirmed now, supersedes any transaction that has a timelock that forces it to be confirmed later." It seems likely that future mechanisms will use the same assumption.Proposed sidechains often include a delay between when a sidechain coin is burned, and the corresponding mainchain coin is released. This delay exists to allow showing of a counterproof that the supposed side-to-main transfer did not actually exist in the sidechain. It appears that the MAD-HTLC argument would apply to such mechanisms, and it is crucial to investigate it further until we are fully convinced that the MAD-HTLC argument does not apply.
Updated on: 2023-06-14T02:31:54.631704+00:00