[Bitcoin-development] Punishing empty blocks?

Michael Grønager gronager at mac.com
Tue May 29 08:52:49 UTC 2012


Peter, I like the idea of being able to know what fees to expect from different miners (it is like a service description / SLA for their service), but I would prefer a more distributed discovery mechanism for the information on the fees (Spent 10 years on Grid Computing...).

Miners could e.g. include a pointer to a webpage (or even their min fee) in the coinbase (encoded properly, like the "/P2SH/" string for BIP0016). That way clients could look it up them selves or you could create sites accumulating this information from the chain it self.

So something like :
        const char* service_sla = "|https://my_ubercool_asic_mining_pool/sla.php|";
        COINBASE_FLAGS << std::vector<unsigned char>(service_sla, service_sla+strlen(service_sla));
 
The format of the sla.php page should then be specified too - but it could be a json-rpc call returning a json object like (as result):
{ 
    sla_version: "0.1",
    accept_no_fee_tx: false,
    min_fee: 50000,
    big_tx_fee: 10000, // extra fee pr kb
}
I guess miners could work out a more suitable set of fees...

Seems like this calls for a BIP ?

/M



On 28/05/2012, at 16:54, Peter Vessenes wrote:

> One of the issues here though is that it would be nice if miners published their own tx rules -- it might be hard to impute them from data.
> 
> I had started a thread about this on bitcoin.org some time ago, and I don't recall what the general outcome was.
> 
> I had imagined an open service whereby a miner could publish a short string in their conbase tying to the service and the service would have different metadata, including the miner's transaction guarantees.
> 
> We offered to host this before, and would still be willing to host such a service.
> 
> Peter
> 
> On Sat, May 26, 2012 at 7:52 AM, Stefan Thomas <moon at justmoon.de> wrote:
> Zooko is spot on - slower confirmations will give people a reason to set
> higher fees. As soon as fees reach a level where they matter, even
> botnet operators will be looking into ways of including transactions for
> some extra profit.
> 
> In the meantime slightly slower confirmations aren't a problem. Consider
> that even if it takes four blocks to get your transaction included
> instead of one, once it is included, you still benefit from every new
> block in terms of security. So if you're looking for six confirmations
> for example, even a three block delay will only be a 50% delay for you.
> And of course there are techniques for instant transactions which
> continue to be refined and improved.
> 
> As for the proposed solutions: Punishing 1-tx blocks is complete and
> utter nonsense. It's trivial to include a bogus second transaction.
> 
> Any additional challenges towards miners like hashes of the previous
> block are at best useless. If I was running a botnet, I'd just grab that
> hash from a website (pretty good chance Blockchain.info will have it :P)
> or mining pool or wherever and keep going undeterred. At worst they may
> affect scalability one day. You might imagine a peer-to-peer network of
> miners who for cost reasons don't download all blocks anymore, but
> verify only a percentage of them at random. They might then exchange
> messages about invalid blocks including a proof (invalid tx, merkle
> branch) why the block is invalid. This is just one idea, the point is
> that assumptions about what a legitimate miner looks like may not always
> hold in the future.
> 
> Finally, there is an ethical aspect as well. If a miner wishes not to
> include my transaction that is his choice. He has no more an obligation
> to sell his service to me than I have to buy it from him. If I really,
> really want him to include my transaction I will have to offer to pay more.
> 
> If we as developers think that confirmations are too slow or that more
> blocks should include transactions, then the right measures would be:
> 
> - Educating users about the relationship between confirmation speed and fees
> - Raising the default transaction fee
> 
> Every market has a supply curve, so it is economically to be expected
> that there will be some miners who don't include transactions, simply
> because they are at that end of the supply curve where it is not worth
> it for them to sell their service. All markets must have a certain
> tension - there must be miners who don't include transactions for there
> to be users who want their transactions included more quickly. In other
> words there must be somebody not confirming if confirmations are to have
> value. If you interfere with that all you'll accomplish is keep
> transaction fees below market level, which will make the transition from
> inflation-financed hashing to transaction-financed hashing more painful
> and disruptive.
> 
> Cheers,
> 
> Stefan
> 
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> 	
> Peter J. Vessenes
> CEO, CoinLab
> M: 206.595.9839
> Skype: vessenes
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Michael Gronager, PhD
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