Integrating Xtreme Thinblocks and Xpress Validation in Bitcoin Classic


New Member
Jan 28, 2016
First off, let me thank the Bitcoin Unlimited team for the amazing work done so far. I'm a really big fan of Xtreme Thinblocks and I hope we can work together to get this feature merged into Classic. I'm really excited to have the opportunity to help in this process anyway that I can.

I've reach a somewhat stable point in merging the code into the Classic development branch, so I have opened a work in progress PR # 147. The code should compile, pass all tests, and exchange thin block information with unlimited clients (though locally I have to revert back to an older style of xthinblocks to be compatible with Unlimited release 12). Next week my major focus will be to comb through the code and find the mistakes that I made during the merge.

I'm new to the bitcoin development scene, so I apologize in advance if I am slow. Please let me know if there is anything I am doing wrong, or anything I could do better.

Thanks again, I am looking forward to working with everyone!
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Well-Known Member
Aug 26, 2015
Thanks for joining us here @rustyloy and thanks for your tireless work on Classic. Great to hear you're integrating this. It's incredibly important to try and convince miners to try and re-decentralize their block propagation through the p2p network:if that's possible. I think it is.

Classic and BU ultimately have the same values and foresee a similar future so it's great to see the collaboration.
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Staff member
Aug 22, 2015
Nice work. Once the Classic nodes have this, it will be a powerful demonstration to Core users that they are being deliberately disadvantaged by their devs.

One enhancement we have been discussing is a dynamic hash size, which for example, moves +/-8 bits depending upon whether a collision is seen (>1 per week) requiring a standard block request. So that the Xthin-using network will self-optimize to the shortest viable hash size, and thinnest blocks.
A phase II project.
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Peter Tschipper

Active Member
Jan 8, 2016
@rustyloy Let me know if you have any questions about what's in the code for xthinblocks or how it works. Mostly everything is identified in our code by //BUIP010 Xtreme thinblocks - begin and end sections or Xpress Validation begin/end ...maybe you've already see that. Anyway, as I said, let me know if you have questions.
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New Member
Feb 7, 2024
Hey, great job on the progress with Bitcoin Unlimited's Xtreme Thinblocks. It's cool to see your effort to merge it into Classic.