I want to explain Segwit2x, because over 95% of Bitcoin exchanges and mining companies have reconfirmed their support for SegWit2x!
Segwit2x is the project to merge into Bitcoin a minimal patch that aims to untangle the current conflict between different political positions regarding segwit activation vs. an increase of the on-chain blockchain
space through a standard block size increase.
It is not a new solution, but it should be seen more as a least common denominator.
Segwit2x combines segwit as it is today in Bitcoin 0.14+ with a 2MB block size hard-fork activated ONLY if segwit activates (95% of miners signaling), but at a fixed future date.
The sole objective of this proposal is to re-unite the Bitcoin community and avoid a cryptocurrency split. Segwit2x does not aim to be best possible technical solution to solve Bitcoin technical limitations.
However, this proposal does not imply a compromise to the future scalability or decentralization of Bitcoin, as a small increase in block size has been proven by several core and non-core developers not to affect Bitcoin value propositions.
In the worst case, a 2X block size increase has much lower economic impact than the last bitcoin halving (<10%), which succeeded without problem.
On the other side, Segwit2x primary goal is to be minimalistic: in this patch some choices have been made to reduce the number of lines modified in the current Bitcoin Core state (master branch), instead of implementing the most elegant solution. This is because I want to reduce the time it takes for core programmers and reviewers to check the correctness of the code,
and to report and correct bugs.
The patch was built by forking the master branch of Bitcoin Core, mixing a few lines of code from Jeff Garzik's BIP102, and defining a second versionbits activation bit (bit 2) for the combined activation.
This means that segwit would be activated before 2Mb: this is inevitable, as versionbits have been designed to have fixed activation periods and thresholds for all bits. Making segwit and 2Mb fork activate together at a delayed date would have required a major re-write of this code, which would contradict the premise of creating a minimalistic patch. However, once
segwit is activated, the hard-fork is unavoidable.
Bit 2 signaling StartTime = April 29th, 2017
Bit 2 signaling Timeout = August 29th, 2017
HardForkTime = Thu, 14 Dec 2017 00:00:00 GMT