Are there any examples of sidechains which target a block time much longer than bitcoin? Could a sidechain be made "slow enough" such that the size of a proof (SPV proof?) for it could actually fit into and be verified by a mainchain bitcoin transaction with the currently-in-effect mainchain protocol rules?

I'm interested in learning more about how a sidechain with a targeted time between blocks of, say, 1 week, might work and/or if such a chain, if it existed, could be useful.

I'm specifically interested in proof-of-work sidechains that do not rely on any sort of federation (as such, Liquid and RSK would not meet this criteria at the moment, but I'm unaware of any other current examples of bitcoin sidechains), and I'm most interested in "slow sidechains," if any exist.


While the idea is interesting, storing the size of the proofin the block itself, it would make the blocks larger, perhaps redundant, but again if we think from the perspective of "light nodes" and other clients, not full nodes this could be beneficial, but in general: Bigger blocks lead to more time for nodes -> less nodes -> more centralization But if you have a particular use case in mind for a 1 week block rate, or bigger blocks, it would be interesting to see how it works and I would love to contribute to your project.

  • Hi, thanks for your answer. However, I'm not suggesting anything about making blocks bigger. In fact, for a "slow" sidechain, and depending on the use case, I think the blocks of the side chain may even end up extremely small. Naturally this would render such a sidechain useless as a "money" for any on-side-chain transactions, but nevertheless such a side chain could still support some off chain (lightning-like) protocols. There may, of course, be other use-cases too. – philbw4 Jan 20 '20 at 4:23
  • Ahhh, My bad, anyways your comment made me think ( with the brain of Google ) and I came across an article by the Vitalik Buterin in 2015, check it out, On Slow and Fast Block Times It is such an interesting discussion, I'm a little new to the blockchain space and everyday I get to learn something that makes me wonder. – yozaam Jan 21 '20 at 16:58

We could introduce slow, secure side chains without sacrificing the decentralisation, and without increasing the block size on Bitcoin using Time Locks and Verifiable Delay Functions that can control the block time. In fact, Time Locks are used in some of the Bitcoin Payment Channel implementations. Please find a nice explanation of Time Locks from Bitcoin Wiki.

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