[Bitcoin-development] BIP draft - Auxiliary Header Format

[Tier Nolan]

I was going to look into creating reference code for this.

The first BIP could be reasonably easy, since it just needs to check for
the presence of the 2 special transactions.

That would mean that it doesn't actually create version 3 blocks at all.

Ideally, I would make it easy for miners to mine version 3 blocks.  I could
add a new field to the getblocktemplate that has the 2 transactions ready
to go.

What do pools actually use for generating blocks.  I assume it's custom
code but that they use (near) standard software for the memory pool?


On Mon, Nov 10, 2014 at 11:39 PM, Tier Nolan <tier.nolan at gmail.com> wrote:

> I have added the network BIP too.  It only has the aheaders message and
> the extra field for getheaders.
>
>
> https://github.com/TierNolan/bips/blob/aux_header/bip-aux-header-network.mediawiki
>
> The transaction definitions are still at:
>
> https://github.com/TierNolan/bips/blob/aux_header/bip-aux-header.mediawiki
>
> On Mon, Nov 10, 2014 at 9:21 PM, Tier Nolan <tier.nolan at gmail.com> wrote:
>
>> I updated the BIP to cover only the specification of the transactions
>> that need to be added.  I will create a network BIP tomorrow.
>>
>> On Mon, Nov 10, 2014 at 11:42 AM, Tier Nolan <tier.nolan at gmail.com>
>> wrote:
>>
>>> The aheaders message is required to make use of the data by SPV
>>> clients.  This could be in a separate BIP though.  I wanted to show that
>>> the merkle path to the aux-header transaction could be efficiently encoded,
>>> but a reference to the other BIP would be sufficient.
>>>
>>> For the other messages, the problem is that the hash of the aux header
>>> is part of the block, but the aux header itself is not.  That means that
>>> the aux header has to be sent for validation of the block.
>>>
>>> I will change it so that the entire aux-header is encoded in the block.
>>> I think encoding the hash in the final transaction and the full aux-header
>>> in the 2nd last one is the best way to do it.  This has the added advantage
>>> of reducing the changes to block data storage, since the aux-header doesn't
>>> have to be stored separately.
>>>
>>>
>>> On Mon, Nov 10, 2014 at 12:52 AM, Gregory Maxwell <gmaxwell at gmail.com>
>>> wrote:
>>>
>>>> Some initial comments...
>>>>
>>>> Tying in the protocol changes is really confusing and the fact that
>>>> they seem to be required out the gates would seemingly make this much
>>>> harder to deploy.   Is there a need to do that? Why can't the p2p part
>>>> be entirely separate from the comitted data?
>>>>
>>>> On Mon, Nov 10, 2014 at 12:39 AM, Tier Nolan <tier.nolan at gmail.com>
>>>> wrote:
>>>> > I made some changes to the draft.  The merkleblock now has the
>>>> auxiliary
>>>> > header information too.
>>>> >
>>>> > There is a tradeoff between overhead and delayed transactions.  Is
>>>> 12.5%
>>>> > transactions being delayed to the next block unacceptable?  Would
>>>> adding
>>>> > padding transactions be an improvement?
>>>> >
>>>> > Creating the "seed" transactions is an implementation headache.
>>>> >
>>>> > Each node needs to have control over an UTXO to create the final
>>>> transaction
>>>> > in the block that has the digest of the auxiliary header.  This means
>>>> that
>>>> > it is not possible to simply start a node and have it mine.  It has to
>>>> > somehow be given the private key.  If two nodes were given the same
>>>> key by
>>>> > accident, then one could end up blocking the other.
>>>> >
>>>> > On one end of the scale is adding a transaction with a few thousand
>>>> outputs
>>>> > into the block chain.  The signatures for locktime restricted
>>>> transactions
>>>> > that spend those outputs could be hard-coded into the software.  This
>>>> is the
>>>> > easiest to implement, but would mean a large table of signatures.  The
>>>> > person who generates the signature list would have to be trusted not
>>>> to
>>>> > spend the outputs early.
>>>> >
>>>> > The other end of the scale means that mining nodes need to include a
>>>> wallets
>>>> > to manage their UTXO entry.  Miners can split a zero value output
>>>> into lots
>>>> > of outputs, if they wish.
>>>> >
>>>> > A middle ground would be for nodes to be able to detect the special
>>>> > transactions and use them.  A server could send out timelocked
>>>> transactions
>>>> > that pay to a particular address but the transaction would be
>>>> timelocked.
>>>> > The private key for the output would be known.  However, miners who
>>>> mine
>>>> > version 2 blocks wouldn't be able to spend them early.
>>>> >
>>>> >
>>>> > On Sat, Nov 8, 2014 at 11:45 PM, Tier Nolan <tier.nolan at gmail.com>
>>>> wrote:
>>>> >>
>>>> >> I created a draft BIP detailing a way to add auxiliary headers to
>>>> Bitcoin
>>>> >> in a bandwidth efficient way.  The overhead per auxiliary header is
>>>> only
>>>> >> around 104 bytes per header.  This is much smaller than would be
>>>> required by
>>>> >> embedding the hash of the header in the coinbase of the block.
>>>> >>
>>>> >> It is a soft fork and it uses the last transaction in the block to
>>>> store
>>>> >> the hash of the auxiliary header.
>>>> >>
>>>> >> It makes use of the fact that the last transaction in the block has
>>>> a much
>>>> >> less complex Merkle branch than the other transactions.
>>>> >>
>>>> >>
>>>> https://github.com/TierNolan/bips/blob/aux_header/bip-aux-header.mediawiki
>>>> >>
>>>> >
>>>> >
>>>> >
>>>> ------------------------------------------------------------------------------
>>>> >
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>>>> > Bitcoin-development at lists.sourceforge.net
>>>> > https://lists.sourceforge.net/lists/listinfo/bitcoin-development
>>>> >
>>>>
>>>
>>>
>>
>
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