Bitcoin Forum

Does anyone know if there is a detailed explanation of how the segregated witness proposal works, i.e. a white paper or similar?

I've had little luck looking on-line and can only find overviews of it's proposed capabilities.

When we broadcast a transaction we not only say but send 'this amount to that address' but we also include an authentication proof in the form of transaction ID, signature etc, which is useful as a witness but useless in the chain of transaction that defines a coin. So we can separate the two into different layers and discard the witness part of the transaction when no longer required.

In fact, this witnessing occupies 2/3rd of the blockchain.

"Witness" is a term in cryptography, so you can find it in many books.
The implementation of this, you can find in elements sidechain on github.

Thanks.

I think this commit (https://github.com/ElementsProject/elements/commit/663e9bd32965008a43a08d1d26ea09cbb14e83aa) over in Alpha covers the feature, or at least a significant portion of it. I can't find anything more significant but I'm guessing we'll know more soon.

EDIT: If you check out Rusty's thread on the lightning-dev (http://lists.linuxfoundation.org/pipermail/lightning-dev/2015-November/thread.html) mailing list, some more details are emerging. Sounds like somebody (Pieter, I'd imagine) will be giving a talk at the next Scaling Bitcoin conference, and there are rough details of how both soft and hard forks would work. (I assume the code I linked to is for a hard fork, and probably not in a deployable state.) Interesting stuff. Looking forward to hearing more about it.

Some more explanation of segregated witness can be found here:

http://lists.linuxfoundation.org/pipermail/lightning-dev/2015-November/000326.html

http://gnusha.org/bitcoin-wizards/2015-11-19.log
http://gnusha.org/bitcoin-wizards/2015-11-08.log

http://diyhpl.us/wiki/transcripts/gmaxwell-sidechains-elements/
https://github.com/ElementsProject/elementsproject.github.io#segregated-witness
https://people.xiph.org/~greg/blockstream.gmaxwell.elements.talk.060815.pdf

https://github.com/ElementsProject/elements/commit/663e9bd32965008a43a08d1d26ea09cbb14e83aa

http://lists.linuxfoundation.org/pipermail/lightning-dev/2015-November/000322.html
http://lists.linuxfoundation.org/pipermail/lightning-dev/2015-November/000316.html
http://lists.linuxfoundation.org/pipermail/lightning-dev/2015-November/000310.html

Note that there are no backlinks to this thread (with the exception of a link I dropped in the -wizards logs), so please don't expect novel contributions placed here (if any) to be as easily found for individuals starting from those links rather than from this thread. Perhaps ping them if you do. Thanks.

We have a new design, a logical refinement from the earlier one, which is substantially better and also solves some additional problems.  Note for the future: things written before BIP _XXX_ will only be somewhat applicable to the segwitness created by the BIP.

Thanks Greg, and thanks to Pieter (and Luke and anybody else who had a hand in SW) for working hard on BIP 62 v2.0. ;) Looking forward to hearing about the final details.

The two #bitcoin-wizards logs seem to explain it, including sipa/Pieter's current (and, in all likelihood, not-quite-final) implementation. I'd recommend reading that, while keeping in mind that the BIP is a work-in-progress, and that Pieter's presentation at Scaling Bitcoin next month should be a much easier way to understand what's going on.

That being said, the basic idea really isn't that hard to understand. The technical details do seem a bit tricky, though. I think I have an idea of how it'll work but will wait for the final presentation and BIP.

Thanks for all the links and for doing the research

I've been looking for more info on this as well

Helped me a lot