[Bitcoin-development] BIP draft - Auxiliary Header Format

Tier Nolan tier.nolan at gmail.com
Mon Nov 10 23:39:23 UTC 2014


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
>>> >>
>>> >
>>> >
>>> >
>>> ------------------------------------------------------------------------------
>>> >
>>> > _______________________________________________
>>> > Bitcoin-development mailing list
>>> > Bitcoin-development at lists.sourceforge.net
>>> > https://lists.sourceforge.net/lists/listinfo/bitcoin-development
>>> >
>>>
>>
>>
>
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