IRC meeting summary for 2016-08-11


Notes / short topics

  • Jtimon asked for some codereview on PR #8493 (Untested: libconsensus: Expose VerifyHeader)
  • Jl2012 has suggested some changes to prevent DoS attacks with segwit (PR #8499), sipa asks what the opinions are on adding a per txin witness size limit policy. Luke-jr notes matching the P2SH consensus limit is too small for N-of-15 multisigs, so a slightly larger limit may be desirable. Sipa will make a proposal by next meeting.
  • Sipa raises awareness around the different sets of flags, namely mandatory flags, consensus flags and standardness. Nodes who send transactions violating rules wich are mandatory will be banned, which causes the network to partition if there are nodes relaying those transactions.

Main topics

  • softfork to make low-s required
  • 0.13.0 RC3

softfork to make low-s required


A source of malleability is the ‘S’ value in the ECDSA signature which can have 2 values, a high and low value. Last year a policy was introduced to have nodes require the low-s value (talked about in the 2015-10-08 meeting). Sipa now proposes to make this a consensus rule, instead of just a policy.

meeting comments

High-s transactions have been non-standard for a long time and not present on the network for over a year. As this is non-controversial and easy to do (one line of code) the main question is whether to deploy it simultaneous with segwit or separate. Sipa argues it might be hard to do this as a separate softfork as it has very low benefit while miners still need to update their software. GreenIsMyPepper and sipa note it would be cleaner to never have high-s values in segwit.

meeting conclusion

  • Combine the enforcement of low-s rules together with segwit.

0.13.0 RC3


The Bitcoin Core team is working towards the 0.13.0 release (full schedule) and RC3 is available since 2016-08-13.

meeting comments

Wumpus wonders if there’s anything that still needs to be merged/backported to 0.13.0.

Luke-jr wants to make a PR to map blockmaxsize to blockmaxweight while segwit is unactivated to make PR #8459 uncontroversial.

There’s a PR for the blog post about 0.13.0 which could use review.

Cfields wonders whether default_witness_commitment should be added to GBT with to witness data for 0.13.0. Sipa thinks a miner on 0.13.0 should never produce a segwit commitment, this way we don’t have sudden behavior changes at times which are far away from updating the software which might break downstream mining infrastructure, gmaxwell adds.

meeting conclusion

Comic relief

wumpus          can anyone do the giant highlight list?
cfields         gmaxwell: paging bot
gmaxwell        #bitcoin-core-dev Meeting: wumpus sipa gmaxwell jonasschnelli morcos luke-jr btcdrak sdaftuar jtimon cfields petertodd kanzure bluematt instagibbs phantomcircuit codeshark michagogo marcofalke paveljanik NicolasDorier
michagogo       cfields: I think last time he said it's not a bot...
wumpus          michagogo: all bots say that!

jtimon          yay 0.13.0!
gmaxwell        jtimon: careful, you're going to trigger some confused reddit posts.
jtimon          oops, sorry, yay ack rc3


IRC nick Name/Nym
sipa Pieter Wuille
gmaxwell Gregory Maxwell
wumpus Wladimir van der Laan
btcdrak BtcDrak
kanzure Bryan Bishop
cfields Cory Fields
GreenIsMyPepper Joseph Poon
jonasschnelli Jonas Schnelli
jl2012 Johnson Lau
luke-jr Luke Dashjr
jtimon Jorge Timón
instagibbs Gregory Sanders


This summary was compiled without input from any of the participants in the discussion, so any errors are the fault of the summary author and not the discussion participants.