Re: [bitcoin-dev] [BIP Proposal] BetterHash Mining Protocol Replacements

From: Matt Corallo <lf-lists@mattcorallo•com>
To: Chris Pacia <ctpacia@gmail•com>,
	Bitcoin Protocol Discussion
	<bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] [BIP Proposal] BetterHash Mining Protocol Replacements
Date: Wed, 6 Jun 2018 15:16:09 -0400	[thread overview]
Message-ID: <6051657f-7cef-be18-06a5-0f5a7b073ef2@mattcorallo.com> (raw)
In-Reply-To: <039bd3d3-c71c-8d40-7456-bc78fc0c7123@gmail.com>

Clients "inspecting and modifying the transactions" is explicitly *not*
supported. There should be more than enough features for clients to get
bitcoind to generate the exact block they want already available via
Bitcoin Core. The only reason transactions are exposed over the work
protocol at all, really, is so that clients can generate weak blocks to
be sent to the pool for efficient client -> pool block relay, not sure
that's worth bothering to add a whole new endpoint for, sounds
needlessly complicated (and the spec is already more than complicated
enough, sadly).

Matt

On 06/05/18 21:26, Chris Pacia via bitcoin-dev wrote:
> Really like that you're moving forward with this. A few months ago I was
> working on something similar as it seemed like nobody else was interested.
> 
> In regards to the specific proposal, would it make sense to offer a tx
> subscription endpoint in addition to TRANSACTION_DATA_REQUEST? Such an
> endpoint could respond to the subscription with the current full list of
> transactions and then push the diff every time a new template is pushed.
> A client that wants to inspect and modify the transactions would use
> quite a bit less data than polling the request endpoint.
> 
> 
> On 06/05/2018 02:44 PM, Matt Corallo via bitcoin-dev wrote:
>> Been working on this one for a while, so its already been through a few
>> rounds of feeback (thanks to all those who already have provided
>> feedback)!
>>
>> At a high level, this meets a few goals:
>>
>> 1) Replace getblocktemplate with something that is both more performant
>> (no JSON encoding, no full transactions sent over the wire to update a
>> job, hence we can keep the same CTransactionRef in Bitcoin Core making
>> lots of validation things way faster), more robust for consensus changes
>> (no need to add protocol changes to add commitments ala SegWit in the
>> future), and moves more block-switching logic inside of the work
>> provider (allowing Bitcoin Core to better optimize work switching as it
>> knows more than an outside pool server, specifically we can play more
>> games with how we do mempool eviction, empty block mining, and not
>> mining fresh transactions more easily by moving to a more "push" model
>> from the normal "pull" getblocktemplate implementation).
>>
>> 2) Replace Stratum with something more secure (sign messages when
>> applicable, without adding too much overhead to the pool), simpler to
>> implement (not JSON-wrapped-hex, no 32-byte-swapped-per-4-byte-byteorder
>> insanity), and better-defined (a clearly written spec, encompassing the
>> various things shoved backwards into stratum like suggested difficulty
>> in the password field and device identification by setting user to
>> "user.device") with VENDOR_MESSAGEs provided for extensibility instead
>> of conflicting specifications from various different vendors.
>>
>> 3) Provide the ability for a pool to accept work which the users of the
>> pool selected the transactions for, providing strong decentralization
>> pressure by removing the network-level centralization attacks pools can
>> do (or be compromised and used to perform) while still allowing them
>> full control of payout management and variance reduction.
>>
>> While (1) and (2) stand on their own, making it all one set of protocols
>> to provide (3) provides at least the opportunity for drastically better
>> decentralization in Bitcoin mining in the future.
>>
>> The latest version of the full BIP draft can be found at
>> https://github.com/TheBlueMatt/bips/blob/betterhash/bip-XXXX.mediawiki
>> and implementations of the work-generation part at
>> https://github.com/TheBlueMatt/bitcoin/commits/2018-02-miningserver and
>> pool/proxy parts at https://github.com/TheBlueMatt/mining-proxy (though
>> note that both implementations are currently on a slightly out-of-date
>> version of the protocol, I hope to get them brought up to date in the
>> coming day or two and make them much more full-featured. The whole stack
>> has managed to mine numerous testnet blocks on several different types
>> of hardware).
>>
>> Matt
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> 
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