Re: [Bitcoin-development] BIP draft - Auxiliary Header Format

[Tier Nolan <tier.nolan@gmail.com>]

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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@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@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@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@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@lists.sourceforge.net
>> > https://lists.sourceforge.net/lists/listinfo/bitcoin-development
>> >
>>
>
>

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