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Date: Wed, 10 Jun 2015 14:18:30 -0700
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From: Aaron Voisine <voisine@gmail.com>
To: Mike Hearn <mike@plan99.net>
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Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Proposal: SPV Fee Discovery mechanism
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The other complication is that this will tend to be a lagging indicator
based on network congestion from the last time you connected. If we assume
that transactions are being dropped in an unpredictable way when blocks are
full, knowing the network congestion *right now* is critical, and even then
you just have to hope that someone who wants that space more than you do
doesn't show up after you disconnect.


Aaron Voisine
co-founder and CEO
breadwallet.com

On Wed, Jun 10, 2015 at 1:26 PM, Mike Hearn <mike@plan99.net> wrote:

> I described an alternative way for SPV wallets to learn about fees some
> time ago. It requires a new transaction version that embeds output values
> into the signed data. Then an upgrade to the P2P protocol to send UTXO data
> along with transactions when they are relayed.
>
> The idea is that the wallet sets a Bloom filter with an FP rate that
> ensures it will see some random subset of all transactions being broadcast
> on the network, and with the extra data, it can calculate the fee paid.
> Once a transaction broadcast is observed the wallet includes that tx hash
> in its next Bloom filter, thus it can see which block the tx confirmed in.
> By measuring the amount of time that passed between a broadcast and it
> appearing in a block, it can calculate its own tables of fee paid:time
> taken.
>
> This has the advantage that you don't have to trust miners to publish data
> accurately. However it requires some protocol upgrades and of course, a lot
> of new code in SPV wallets.
>
> The way Bitcoin Wallet for Android handles fees currently is to just
> update a hard coded value every so often.
>
>
> ------------------------------------------------------------------------------
>
> _______________________________________________
> Bitcoin-development mailing list
> Bitcoin-development@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/bitcoin-development
>
>

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<div dir=3D"ltr">The other complication is that this will tend to be a lagg=
ing indicator based on network congestion from the last time you connected.=
 If we assume that transactions are being dropped in an unpredictable way w=
hen blocks are full, knowing the network congestion *right now* is critical=
, and even then you just have to hope that someone who wants that space mor=
e than you do doesn&#39;t show up after you disconnect.</div><div class=3D"=
gmail_extra"><br clear=3D"all"><div><div class=3D"gmail_signature"><div dir=
=3D"ltr"><div><div dir=3D"ltr"><div><br>Aaron Voisine</div><div>co-founder =
and CEO<br><a href=3D"http://breadwallet.com" target=3D"_blank">breadwallet=
.com</a></div></div></div></div></div></div>
<br><div class=3D"gmail_quote">On Wed, Jun 10, 2015 at 1:26 PM, Mike Hearn =
<span dir=3D"ltr">&lt;<a href=3D"mailto:mike@plan99.net" target=3D"_blank">=
mike@plan99.net</a>&gt;</span> wrote:<br><blockquote class=3D"gmail_quote" =
style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><di=
v dir=3D"ltr">I described an alternative way for SPV wallets to learn about=
 fees some time ago. It requires a new transaction version that embeds outp=
ut values into the signed data. Then an upgrade to the P2P protocol to send=
 UTXO data along with transactions when they are relayed.<div><br></div><di=
v>The idea is that the wallet sets a Bloom filter with an FP rate that ensu=
res it will see some random subset of all transactions being broadcast on t=
he network, and with the extra data, it can calculate the fee paid. Once a =
transaction broadcast is observed the wallet includes that tx hash in its n=
ext Bloom filter, thus it can see which block the tx confirmed in. By measu=
ring the amount of time that passed between a broadcast and it appearing in=
 a block, it can calculate its own tables of fee paid:time taken.</div><div=
><br></div><div>This has the advantage that you don&#39;t have to trust min=
ers to publish data accurately. However it requires some protocol upgrades =
and of course, a lot of new code in SPV wallets.</div><div><br></div><div>T=
he way Bitcoin Wallet for Android handles fees currently is to just update =
a hard coded value every so often.</div></div>
<br>-----------------------------------------------------------------------=
-------<br>
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Bitcoin-development mailing list<br>
<a href=3D"mailto:Bitcoin-development@lists.sourceforge.net">Bitcoin-develo=
pment@lists.sourceforge.net</a><br>
<a href=3D"https://lists.sourceforge.net/lists/listinfo/bitcoin-development=
" target=3D"_blank">https://lists.sourceforge.net/lists/listinfo/bitcoin-de=
velopment</a><br>
<br></blockquote></div><br></div>

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