Hi there,

I hope everyone who celebrates Christmas is having a relaxing and enjoyable break! :)

I'd like to announce Bitcoin XT, a patch set on top of Bitcoin Core 0.10rc1 that focuses on enhancements to the peer to peer protocol. It is reproducibly built with gitian and there are binaries for Linux, OS X and Windows (code signed). It currently contains the following two features:
  1. Double spend relaying, by Gavin Andresen and Tom Harding. This is useful for merchants that currently connect to thousands of nodes to spot double spends, which is wasteful of resources.

  2. BIP 64 support (the getutxo message). This is useful for Lighthouse to render a more helpful GUI.
By running XT you provide additional services to users of the P2P network, test the features more thoroughly and help build the case for inclusion in Bitcoin Core.

There is a mailing list for discussion of patch inclusion, and another list for announcements. Because XT is a patch set the feature branches will be rebased from time to time. If you branch from them, be aware of that and plan accordingly.

XT nodes advertise themselves by using the getutxo service bit (i.e. bit 2). You can find them by querying a Cartographer, which I will describe in another email.



A brief note about the goals of this project. The XT project is intended to provide a friendly environment where [SPV] app developers and merchants can experiment with new features and explore new directions for the protocol, if there is demand for that. Those upgrades could then be considered for inclusion into Core at a later date. I do not expect there to be thousands of XT users any time soon, but that's OK. Because the patch set contains features that don't require everyone to opt in (e.g. changes to the tx/block formats), even just a few nodes can be useful.


Thanks for reading, and have a great new year's eve!