Add a moving checkpoint to the Bitcoin protocol



Summary:

The proposal for a "moving checkpoint" to be added to the Bitcoin protocol is being discussed among developers. The rule is similar to that already implemented in NXT coin where a node ignores any new block under a certain height, making the blockchain truly immutable after a set number of blocks. However, concerns have been raised about the vulnerability of this rule to 51% attacks. In response, it has been suggested that if a node detects a fork with both sides having a length greater than 144 blocks, it should halt and request user intervention to determine which chain to follow. This is not a proposal for adoption but rather a suggestion for improving security. The proposed rule aims to address network splits that last longer than the set limit by having nodes stop until the split is fixed, and in extreme cases, nodes from one branch could delete their local history to join the other branch. Two possible situations are considered: protecting older blocks against history rewrites during a 51% attack and addressing network splits. The moving checkpoint is only valid if the difference in blocks between the main chain and the new fork is smaller than X blocks.


Updated on: 2023-06-13T20:39:04.303516+00:00