How does blind merge mining (BMM) work?

The thought is that Bitcoin miners are blind to the sidechain/spacechain that’s being merge-mined.

In regular merge-mining Bitcoin miners that select to take part should run a node on the separate blockchain (Namecoin, Rootstock, for instance) and truly construct the block for these chains, then embody it someplace of their Bitcoin block. See https://bitcoin.stackexchange.com/a/35870/1026 for a extra detailed rationalization.

In blind merge-mining constructs, similar to Spacechains, a brand new position is added between the parallel chain that’s being merge-mined and Bitcoin: that of BMM miners.

The BMM miners acquire charges and construct the blocks on the parallel chain and submit their hash for inclusion on Bitcoin in what we are able to name a BMM transaction. They pay Bitcoin miners a charge in BTC. Bitcoin miners can simply embody these hashes and acquire the charges with out caring about their which means, with out having to run a node on this parallel chain.

It is anticipated that competitors between a number of BMM miners will drive up the BTC charge paid within the BMM transaction as much as principally the identical quantity of charges they acquire on the parallel chain.

The toughest a part of implementing such a protocol is guaranteeing that Bitcoin miners do not embody multiple BMM hash for a similar parallel chain in the identical Bitcoin block. That’s unhealthy as a result of:

1. It may be messy for the parallel chain — it must have tough and complicated guidelines as a way to decide what block is legitimate, for instance.
2. It is wasteful — it is going to use Bitcoin block house for no goal.
3. It undermines the objective of turning charges collected within the parallel chain into BTC paid on to Bitcoin miners — since there isn’t any atomicity ensures between paying the BMM transaction charge and truly having a sound block accepted within the parallel chain, there isn’t any incentive for competing BMM miners to bid the BTC charge as much as the quantity acquired on the parallel chain.

There are a number of methods of reaching these atomicity ensures, such because the Ruben Somsen covenants BMM/Spacechain proposal and the BIP-301/Drivechain proposal.