Subject: Re: [bitcoin-dev] BIP: OP_BRIBVERIFY - the op code needed for Blind Merge Mined drivechains

From: Paul Sztorc <[email-masked]>
Date: Wed, 28 Jun 2017 12:43:22 -0400

Hi Luke,

On 6/28/2017 1:20 AM, Luke Dashjr via bitcoin-dev wrote:
> On Wednesday 28 June 2017 12:37:13 AM Chris Stewart via bitcoin-dev wrote:
>> BRIBEVERIFY redefines the existing NOP4 opcode. When executed, if the given
>> critical hash is included at the given vout index in the coinbase
>> transaction
>> the script evaluates to true. Otherwise, the script will fail.
>>
>> This allows sidechains to be merged mined against
>> bitcoin without burdening bitcoin miners with extra resource requirements.
> 
> I don't see how. It seems like the logical outcome from this is "whoever pays 
> the most gets the next sidechain block"... That's not particularly useful for 
> merge mining.

This is one of the assumptions which BMM exploits, see #4 of:
http://www.truthcoin.info/blog/blind-merged-mining/#focus

The idea is that this is a safe assumption, because it is already the
case today. If we assume that miners revenue-maximize, and further that
the "bidder" frames his payments in tx-fees, then a willing buyer can
control the next block by simply filling it with high tx-fee spam.
Anyone who is willing to pay the most can already 'get' the next
mainchain block (only, indirectly).

> 
>> This enables sidechains in Bitcoin.
> 
> There are different kinds of sidechains...
> 
> Federated peg: this already works on Bitcoin.
> SPV/SNARK peg: this isn't enabled by your BIP.
> Drivechains: this isn't enabled by your BIP.
> 
> How do you say this enables any kind of sidechain?

Yes, it is unclear, but Chris' email is specific to blind merged mining
(BMM), which is kind of a "sidechains +". So this does not directly
enable any sidechains. Instead, it enables the "+" part.

--Paul