Bitcoin Core 0.13.1 is officially released, and Segregated Witness will be activated in the middle of next month

Bitcoin Core 0.13.1 has been officially released today, marking the official introduction of Segregated Witness, the core of the long-awaited Bitcoin Core expansion roadmap. From November 15, Bitcoin miners can signal support for this protocol upgrade, which, if activated, will bring many new features to the Bitcoin network and effectively increase the block size limit.

According to Bitcoin Core developer and Ciphrex CEO Eric Lombrozo,

“SegWit is the largest protocol extension to date.”

Segregated Witness was first publicly proposed by Bitcoin Core and Blockstream developer Dr. Pieter Wuille at the Scaling Bitcoin Conference in Hong Kong in December 2015. This technical innovation separates signature data from Bitcoin transactions.

Segregated witness has many advantages, including plasticity repair, more flexible programmability, and effectively increasing the block size limit.

Lombrozo said:

“SegWit is the most significant improvement to the protocol to date, and makes many exciting innovations possible. We are in the midst of a period of tremendous innovation in Bitcoin — the biggest innovation since Bitcoin’s inception is happening right now.”

The preparation phase of Segregated Witness took nearly a year. Wuille began writing it in November 2015, and in the following months, Lombrozo, Johnson Lau and several other Bitcoin Core developers joined in. Segregated Witness was completed in April, totaling nearly 5,000 lines of code.

Since then, SegWit has been subject to intense scrutiny and analysis. Lombrozo explained:

“We have done a lot of review and have performed a lot of testing. We have three dedicated SegWit testnets. It has been running successfully on the Bitcoin main testnet since May. Additionally, compact blocks have been developed and integrated into Bitcoin Core to alleviate latency and bandwidth issues. This was already available in the previous Core 0.13.0 release.”

activation

Segregated Witness is a soft fork that technically makes the Bitcoin protocol rules more restrictive.

Segregated Witness activation will follow the criteria established by BIP9. This means that during a single 2016 block difficulty period (approximately 2 weeks), at least 95% of the blocks mined by miners must signal support for Segregated Witness. If this threshold is met, the following difficulty period allows everyone to upgrade, after which Segregated Witness support is activated. Segregated Witness transactions will be supported by Bitcoin miners.

Miner signaling support will begin on November 15th. At the earliest, Segregated Witness could be activated in mid-December. However, this is looking unlikely at this point. Recently, Chinese mining pool ViaBTC said they would no longer support the Segregated Witness soft fork. Given that ViaBTC currently controls about 9% of the total network hashrate, this effectively prevents Segregated Witness from activating - assuming ViaBTC maintains at least 5% of the hashrate.

However, Lombrozo said the Bitcoin Core development team is not too worried about this.

“By design, it’s very difficult to change the consensus rules. In this case, I think the benefits far outweigh the risks because SegWit brings a whole host of new innovations to Bitcoin that will improve Bitcoin’s scalability and enable more use cases. I hope miners will appreciate these benefits and want to take advantage of these major protocol improvements.”

If SegWit doesn’t gain 95% support by November 15, 2017, it will never be activated again. Lombrozo said that before then, Bitcoin Core will not be able to come up with an alternative proposal.

“We’ve worked really hard to find a path forward that gives everyone in the ecosystem what they want. It’s impossible to make everyone happy, but we’ve made a huge effort. We’ve pushed the community forward. We hope the community appreciates our work and likes what we’ve done. At this point, the fate of SegWit is in the hands of the community.”

Bitcoin Core 0.13.1 is available for download from bitcoincore.org and bitcoin.org.