Countdown to SegWit: These Are the Dates to Keep an Eye On

Bitcoin’s very public scaling debate is entering a crucial phase. Two of the most popular scaling proposals available today — BIP148 and SegWit2x — both intend to trigger Segregated Witness (“SegWit”) activation within a month, which means that the protocol upgrade could be live within two.At the same time, there is a very real risk that Bitcoin “splits.” Both BIP148 and SegWit2x could diverge from the current Bitcoin protocol, which could in turn lead to even more splits. Here is a list of dates for July, August and beyond to keep an eye on.

SegWit Timeline

 July 14: BTC1 Deployment

The software client that resulted from the New York Agreement is a fork of the Bitcoin Core codebase, called “BTC1.” BTC1’s beta software was released on June 30th. But according to the SegWit2x roadmap, July 14th is the day that signatories to the New York Agreement should test.

 July 21: BIP91 Signaling to Start

Miner signaling should commence.This shouldn’t really affect regular users either.

 July 23 (at the earliest): BIP91 Lock In

The precise threshold for BIP91 activation requires that within a pre-defined series of 336 blocks, 269 blocks must signal readiness. That’s some 80 percent of hash power, over about 2 1/3 days. So assuming the SegWit2x roadmap is followed, BIP91 could, at the very soonest, lock in on July 23rd. Again, this shouldn’t really affect regular users.

 July 25 (at the earliest): BIP91 Activation

On July 25th, another 336 blocks after BIP91 “lock in”, BIP91 could actually go into effect, at the soonest. Any blocks that do not signal readiness for Segregated Witness (per BIP141) will now be rejected.This still shouldn’t really affect regular users. But if you are miner, you should now only mine blocks, and only mine on top of blocks, that signal readiness for SegWit (BIP141). Else you risk having your blocks rejected by a hash power majority.

 July 29: BIP91 Deadline

If Bitcoin miners want to avoid a “split” in Bitcoin’s blockchain and currency, July 29th is a first deadline day for them. To ensure that BTC1’s BIP91 is activated in time to be compatible with BIP148, it should be locked in on this day at the very latest, say, before 08:00 UTC. (That’s 4 am on the U.S. east coast.) But sooner is better: The closer to the deadline BIP91 locks in, the bigger the risk it doesn’t activate in time. If BIP91 has not activated by this deadline, Bitcoin may well be heading for a chain-split. If this happens, and if you are a regular user, and you haven’t prepared for a potential BIP148 UASF chain-split yet, you now have two days left to do so. And you really should. This article explains how.

 July 31: BIP141 Deadline

Technically, July 31st is the miners’ second deadline day to avoid a split. On this day (UTC), at the very latest, either BIP91 must activate, or BIP141 must lock in. In other words, if BIP91 did not lock in in time, there must now have been a two-week difficulty period in which 95 percent of hash power signals support for SegWit. In reality, the chance is small that July 31st actually coincides with the closing day for a difficulty period. As such, both users and miners should have probably already prepared for a potential split, as explained for July 29th. But July 31st really is your last chance to get ready.

 August 1: BIP148 Activation

This is the day BIP148 activates, which makes it the third and final deadline day for miners to avoid a split.On August 1st, at 00:00 UTC (note that this is still July 31st in the U.S.), all BIP148 nodes will start rejecting any blocks that do not signal readiness for Segregated Witness (per BIP141). If BIP141, BIP91 nor BIP148 have attracted sufficient hash power by August 1st, but BIP148 does gain some traction, the chain could split on this day.

 August 4: Potential Bitcoin ABC Launch

Although the exact date is not set in stone, August 4th may see the introduction of a new “Bitcoin”: Bitcoin ABC.Major Bitcoin mining hardware producer Bitmain recently announced that if BIP91 does not activate before August 1st and BIP148 is showing signs of life after August 1st, it will launch a “contingency plan.” More recently, the implementation to embody this contingency plan — named “Bitcoin ABC” — was announced at the Future of Bitcoin conference.

 August 15: Potential BIP148 Proof-of-Work Change

While this date is not set in stone either, August 15th could see the introduction of yet another type of “Bitcoin,” which we’ll refer to as “NewPoW Bitcoin” or “NewPoWBTC.”As a UASF, August 1st’s BIP148 fork is initially effectuated by users — not miners. Users will start to reject any blocks that do not signal readiness for Segregated Witness (per BIP141). This should incentivize miners to follow the BIP148 chain (ideally to the point where it’s the only chain left). But whether this will actually happen remains to be seen.

 Mid- to late- August: SegWit Lock In

If miners avoided a chain-split through BIP141, BIP91 or BIP148, Segregated Witness should at the latest lock in between mid-August or late August.  Should a chain-split happen, it’s always best to hold onto your private keys, and it’s probably best not to transact at all until the situation resolves in some way or another. (For more information, see this article.) For a miner, it’s probably best to just mine the most profitable chain.

 Late August to Mid-September: SegWit Activation

If a chain-split is avoided, SegWit should activate around this time. If you’re running a compatible client by now, you can begin to enjoy the new features while maintaining top-notch security.If a chain-split was not avoided, the situation will probably still be too complex to predict.

Late October to Mid-November: SegWit2x Hard Fork

Toward the end of this year (though potentially even up to early 2018), the hard fork part of SegWit2x should take place. To be exact, this hard fork activates on BTC1 clients three months after SegWit locks in. This activation means that a “base block” bigger than 1 megabyte should be mined, which makes BTC1 clients incompatible with all Bitcoin clients that do not have the hard fork code implemented.At this point in time, it seems almost certain that not everyone will change their software to support this hard fork. Bitcoin’s development community in particular has almost unanumously rejectedthe proposal.

Thanks to the source Aaron van Wirdum

BTC Markets Team


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