Recent block hashes are often included in the signature data to provide an expiration mechanism. The hash for the current tip minus four is used to prevent small reorgs from invalidating signatures. The default behaviour is that when that block is one hour old the signature is no longer valid.
There is an issue here that if it takes one hour to mine four blocks, it will create a situation where no signature can ever be valid. This documentation just describes how the functionality exists now and will be updated in a later review to account for this situation.
Looks good!
There is an issue here that if it takes one hour to mine four blocks, it will create a situation where no signature can ever be valid. This documentation just describes how the functionality exists now and will be updated in a later review to account for this situation.