IRC meeting summary for 2016-05-05


Main topics

  • segwit versionbit, testnet startdate, GBT changes

Short topics

  • NicolasDorier proposed to work on this issue. Morcos commented we should separate wallet functionality to use some smarter higher value for “dust” and the floor for dust should be a separate variable as oposed to a multiple of min relay that it is now. Further discussion was directed to the issue itself.
  • BlueMatt has a BIP document ready for his compact block relay proposal. The document is mailed to the bitcoin-dev mailinglist for further feedback.

segwit versionbit, testnet startdate, GBT changes


Developers are working on a soft fork to introduce segregated witness onto Bitcoin mainnet, with initial testing being performed on a special testnet. Segregated witness (segwit) allows transaction signature data to be stored outside of the data hashed to produce transaction identifiers, removing all known forms of third-party malleability, allowing full nodes to compile the current UTXO set without downloading all signatures, and laying the groundwork for fraud proofs that can allow lightweight (SPV) clients to help enforce more of the consensus rules. The segwit soft fork also allows miners to substitute 1 byte of block space with 4 bytes of segwit data, increasing transaction capacity for wallets that use segwit. segregated witness BIPs: BIP141, BIP142, BIP143, BIP144 and BIP145

meeting comments

Segregated witness needs a BIP9 versionbit to activate. There’s no special reason to pick any specific bit, so it makes sense to pick the next bit in line as it might reduce the chance of accidentally duplicating assignments. There needs to be a document outside of the BIP documentation that keeps track of the current bit assignment.

Testnet needs a starting date for segregated witness. Since it doesn’t need to be set ahead of time, activation could be set on may 1st to get people to test their version of segwit against each other even before merging. Dates for mainnet should be set when the software is known ready for release and should ideally be coordinated with other implementations.

Cfields notes the getblocktemplate(GBT) changes need to get in place quickly so that testnet is a valid representation of what miners will be running. There’s a proposed amendment to BIP9 that would require miners to set a flag signaling awareness of segwit (implementation). If this is adopted GBT clients that are not segwit-ready won’t be creating blocks with segwit transactions. This discussion was delayed until after the meeting.

meeting conclusion

  • Add bip-0009/ in the bips repository to keep track of current bit assignments.
  • Set testnet activation on May 1st, expiration 1 year later.

Comic relief

btcdrak       ok so (1<<1) with activation may 1st for testnet, and (1<<1) and date TDB for mainnet
morcos        btcdrak: ack
morcos        but what does TDB stand for? :)
btcdrak  palms face
gmaxwell      Totally delicious burger.


IRC nick Name/Nym
btcdrak BtcDrak
gmaxwell Gregory Maxwell
jonasschnelli Jonas Schnelli
Morcos Alex Morcos
sipa Pieter Wuille
wumpus Wladimir van der Laan
phantomcircuit Patrick Strateman
sdaftuar Suhas Daftuar
jl2012 Johnson Lau
cfields Cory Fields
Nickler Jonas Nick
instagibbs Gregory Sanders
paveljanik Pavel Janik
achow101 Andrew Chow
NicolasDorier Nicolas Dorier
BlueMatt Matt Corallo


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.