Re: [Bitcoin-development] merged mining hashcash & bitcoin (Re: Coinbase TxOut Hashcash)

[Jeff Garzik <jgarzik@exmulti.com>]

On Tue, May 14, 2013 at 5:25 AM, Adam Back <adam@cypherspace.org> wrote:
> On Mon, May 13, 2013 at 06:00:27PM -0400, Jeff Garzik wrote:
>>
>> When a transaction's input value exceeds its output value, the
>> remainder is the transaction fee.  The miner's reward for processing
>> transactions is the 25 BTC initial currency distribution + the sum of
>> all per-transaction fees.  A destroy-by-miner fee transaction is a
>> normal bitcoin transaction sent by any user, that might look like
>>
>> Input 1: 1.0 BTC
>> Output 1: 0.5 BTC
>>
>> (the miner fee is implicitly 0.5 BTC, paid to whomever mines the
>> transaction into a block)
>>
>> Sadly the bitcoin protocol prevents zero-output,
>> give-it-all-to-the-miner transactions.
>
>
> Well if it is a later transaction, not an integral part of the reward
> transaction (that is definitionally mined by being serialized into the
> coinbase), the user may elect to withhold the promised transaction
> give-to-miner, so thats not so good.

That evaluation largely depends on the needs of the service in question.

In my decentralized identity (SIN) example, you merely need to prove
to the cloud that you sacrificed some bitcoins to any-miner.  The
confirmed, in-chain, non-coinbase transaction becomes the root node
for off-chain identity data.

The penalty for the user withholding the sacrifice transaction is that
their SIN is not created.  That incentive may not exist in that way,
in another service.

> Or do you mean to say you could have (implicit reward 25BTC) and reward
> transaction .001 BTC to self and 24.999 BTC with existing bitcoin format and
> validation semantics?  That would be close enough to give-to-miner.  Also
> the output sum > 0BTC limitation could be changed to >= maybe... (just one
> well placed character :)

Just referring to a standard, fee-bearing, user-created bitcoin
transaction, where output_value < input_value.  The fee is paid to the
first miner who includes that transaction in a block, as part of the
protocol.

-- 
Jeff Garzik
exMULTI, Inc.
jgarzik@exmulti.com