Segregated Witness: Coming to a Bitcoin Core near You

23 Oct


Segregated Witness, a scaling and far-reaching improvement for Bitcoin, could start being implemented across the network as early as November 15th. The technology will have a lot of implications for users of Bitcoin, including potentially lower fees, slightly higher transaction capacity,elimination of the malleability problem, and increased security for multi-signature transactions.

The date of launch for SegWit, as it is called for short, is not yet set in stone. While many developers on the mailing list seemed fine with an activation date of November 15th, at least one developer, Tom Zander, who has created an alternative solution called Flexible Transactions, took issue with the nearness of that date. Zander suggested a two-month timeline as the earliest time to implement SegWit, and also said that for his personal preference, that would be too fast.

Gavin Andresen weighed in on the issue, saying:

I asked a lot of businesses and individuals how long it would take them to upgrade to a new release over the last year or two. […] Nobody said it would take them more than two weeks. […] If somebody is running their own validation code… then we should assume they’re sophisticated enough to figure out how to mitigate any risks associated with segwit activation on their own.

Core developer Matt Corallo also took Zander to task for failing to note the fact that security issues have been found in his Flexible Transactions code:

You keep calling flexible transactions “safer”, and yet you haven’t mentioned that the current codebase is riddled with blatant and massive security holes. For example, you seem to have misunderstood C++’s memory model – you would have no less than three out-of-bound, probably exploitable memory accesses in your 80-LoC deserialize method at [link] if you were to turn on flexible transactions (and I only reviewed that method for 2 minutes). If you want to propose an alternative to a community which has been in desperate need of fixes to many problems for several years, please do so with something which would not take at least a year to complete given a large team of qualified developers.

More pictures and the full article can be found here: