Now that we're going down that path, I'm starting to wonder whether we should
treat inputs, outputs and kernels all in that same way. It's definitely simpler.
Here's the proposal:
- Across the wire, blocks have the regular list of inputs, outputs and kernels.
At the minimum, they must have one output and one kernel (coinbase).
- Blocks can also include the first n bytes of input/output/kernel hashes that
are part of the block but not fully included.
- A node receiving a block with partial hashes checks them against its the
transaction pool.
- Known input/output/kernels are added, missing ones (or collisions) are asked
to the block sending node all in one batch.
- Once everything is known, the full block can be validated.
This still leaves the possibility to have full blocks, including all the data.
In the general case the blocks should be very compact and requests for more
data will only be commonplace for nodes newly started. It also gives an
incentive to miners to have a fairly full transaction pool (to avoid further
requests).
As far as how many bytes of the hash, as John mentioned, 8 bytes (a u64) seem
to suffice. I believe the chances of collisions with a pool of 100,000 elements
would still be less than 0.00000003%. 4 bytes would likely be too small, a
transaction pool of the same size would have 69% of collisions.
- Igno
-------- Original Message --------l
Subject: Re: [Mimblewimble] Compact blocks
Local Time: March 3, 2017 2:47 PM
UTC Time: March 3, 2017 10:47 PM
From: john.tr...@gmail.com
To: Ignotus Peverell <igno.pever...@protonmail.com>,
mimblewimble@lists.launchpad.net
dear Igno,
> That is, the receiver will look up how many kernel she has matching the hint.
> If 0 or more than 1, it will query peers for a list of all known
> matching kernels.
Uhm, that should be: ask the sending peer to expand the hint to a full kernel.
regards,
-John
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