0) Adjust BIP16 & BIP30 enforcement values
1) Reduce amount that peers can adjust our time to eliminate an attack vector. Thanks to
coblee for this fix.
2) Zeitgeist2 patch - thanks to Lolcust and ArtForz. This fixes an issue where a
51% attack can change difficulty at will. Go back the full period unless it's the
first retarget after genesis.
3) Avoid overflow in CalculateNextWorkRequired(). Thanks to pooler for the overflow fix.
4) SegWit ContextualCheckBlockHeader adjustment and extra coverage
5) Reject peer proto version below 70002. Thanks to wtogami for this patch.
6) Adjust default settings for Litecoin
The big notice at the top of the release note is not interesting
to most users now and apparently comes across poorly to some.
Better to provide more information about what we do support.
This disentangles the script validation skipping from checkpoints.
A new option is introduced "assumevalid" which specifies a block whos
ancestors we assume all have valid scriptsigs and so we do not check
them when they are also burried under the best header by two weeks
worth of work.
Unlike checkpoints this has no influence on consensus unless you set
it to a block with an invalid history. Because of this it can be
easily be updated without risk of influencing the network consensus.
This results in a massive IBD speedup.
This approach was independently recommended by Peter Todd and Luke-Jr
since POW based signature skipping (see PR#9180) does not have the
verifiable properties of a specific hash and may create bad incentives.
The downside is that, like checkpoints, the defaults bitrot and older
releases will sync slower. On the plus side users can provide their
own value here, and if they set it to something crazy all that will
happen is more time will be spend validating signatures.
Checkblocks and checklevel are also moved to the hidden debug options:
Especially now that checkblocks has a low default there is little need
to change these settings, and users frequently misunderstand them as
influencing security or IBD speed. By hiding them we offset the
space added by this new option.
Adrian Gallagher