Flyclient Paper

Flyclient: Super-Light Clients for Cryptocurrencies
https://eprint.iacr.org/2019/226

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Thank you for sharing. This is great stuff.

I love the name of the â€śnon-interactive proof of proof-of-work (NIPoPoW)â€ť solution. Itâ€™s such a marketing masterpiece!

EDIT: The important question: can Grin use this? Iâ€™m not smart enough to figure it out, help!

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Yes! Grin can absolutely use this. Itâ€™s on our list of things to do over the next few months.

We have done a lot of the prep work for this (headers commit to the root of the full header MMR, not just the previous header hash).

This has some nice implications for the initial â€śfast syncâ€ť when a new node is started up.
And allows us to start validating full blocks sooner (we can still download the full header chain in the background, but without blocking the rest of the sync process).

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problem solved

Hello, I have read the Flyclient paper for several times, but canâ€™t understand why MMR proof can prove that Bi is the i-th block in blockchain.
Itâ€™s position binding. How does MMR get that?

And it also say that Merkle trees also provide position binding.
Why?
I just canâ€™t understand

What did you discover? Thanks.

gitter history:
Antioch Peverell @antioch May 06 16:08
@jasonzhouu A Merkle proof consists of a path (of sibling hashes) and an MMR size. For a given size of MMR the path implicitly defines the left/right direction at each step in the path (is the node the left or right node beneath its parent?) This implicit series of left/right directions fixes the node at a single leaf position.
A call to proof.verify() takes a position and we use this to reconstruct the left/right decision at each step back up tree to the root (and will only verify if the position and the leaf node data are correct).

ĺ‘¨ĺ®‡ç›› Yusheng Zhou @jasonzhouu May 06 18:25
@antiochp Get it! Thank you very much!
So the prover provide:
path of sibling
the i-index of this block from genesis

ĺ‘¨ĺ®‡ç›› Yusheng Zhou @jasonzhouu May 06 18:30
Then verifier can reconstruct the every direction decision when concatenate siblings, according to the i-index.
Only if the i-index is true, -> then every direction decision is true, -> then the final MMR root is true.

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A new flyclient paper is out https://eprint.iacr.org/2019/226.pdf

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https://diode.io/burning-platform-pki/blockquick-super-light-blockchain-client-for-trustless-time-19144/

https://diyhpl.us/wiki/transcripts/stanford-blockchain-conference/2020/celo-ultralight-client/

The Celo ultralight client

Marek Olszewski and Michael Straka

I think itâ€™s time to move on to developing a wallet for the mobile version, it will give a quick race against the competition.
Flyclient technology is a promising technology for at least 5 years

Another interesting thing is that if we accelerate the network to 10 transactions per second with a reduction in the reward for a block of 60/10 = 6 coins per block, is it possible?