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From: Alex Akselrod <alex@akselrod.org>
Date: Thu, 1 Jun 2017 23:35:29 -0400
Message-ID: <CAE0pnxKD5+rE4aW86C-azrppnk5SaoEXBnwoJjh0mqQPzFSspQ@mail.gmail.com>
To: Bitcoin Dev <bitcoin-dev@lists.linuxfoundation.org>
Content-Type: multipart/alternative; boundary="001a113c1adc5034950550f1d8ca"
Subject: Re: [bitcoin-dev] BIP Proposal: Compact Client Side Filtering for
 Light Clients
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I agree with Greg and Laolu; BIP-37 filtering for transactions is no better
than for blocks and completely destroys privacy.

A constant stream of transactions is OK, but even cheaper for light clients
would be Laolu's proposal of streaming more tx data than existing inv
messages but less than existing tx messages.

We could make a bit field of things to include in every inv-with-metadata
message, such as:
- witness data
- scriptSig data pushes
- scriptPubKey
- hash of scriptPubKey (unnecessary if full scriptPubKey is sent)
- scriptPubKey data pushes
- etc.

This way a full node might be able to tell what application (or type of
application) a light client is running, but not the client's addresses or
outputs, except maybe when the client originates transactions.

On Thu, Jun 1, 2017 at 10:28 PM, Gregory Maxwell via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> On Fri, Jun 2, 2017 at 2:15 AM, Chris via bitcoin-dev
> <bitcoin-dev@lists.linuxfoundation.org> wrote:
> > On 06/01/2017 06:10 PM, Olaoluwa Osuntokun via bitcoin-dev wrote:
> >
> >> One aspect which isn't in this BIP draft is direct support for
> unconfirmed
> >> transactions. I consider such a feature an important UX feature for
> mobile
> >> phones, and something which I've personally seen as an important
> >> UX-experience when on-boarding new users to Bitcoin.
> >
> > Totally agree. My first thought is maybe you could keep bip37 filtering
> > as optional for unconfirmed transactions. Since you're only interested
>
> Really bad for privacy. Data for transactions at the tip is only
> 14kb/s-- potentially less if segwit is in use and you're not getting
> witnesses. Is that really that burdensome?
>
> FWIW, leaving a mobile browser just running while pointed at some
> websites seems to use more traffic than that just loading advertising.
> :)
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>

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<div dir=3D"ltr"><div>I agree with Greg and Laolu; BIP-37 filtering for tra=
nsactions is no better than for blocks and completely destroys privacy.<br>=
<br>A constant stream of transactions is OK, but even cheaper for light cli=
ents would be Laolu&#39;s proposal of streaming more tx data than existing =
inv messages but less than existing tx messages.<br><br>We could make a bit=
 field of things to include in every inv-with-metadata message, such as:<br=
>- witness data<br>- scriptSig data pushes<br>- scriptPubKey<br>- hash of s=
criptPubKey (unnecessary if full scriptPubKey is sent)<br>- scriptPubKey da=
ta pushes<br></div><div><div>- etc.<br><br>This way a full node might be ab=
le to tell what application (or type of application) a light client is runn=
ing, but not the client&#39;s addresses or outputs, except maybe when the c=
lient originates transactions.<br></div></div></div><div class=3D"gmail_ext=
ra"><br><div class=3D"gmail_quote">On Thu, Jun 1, 2017 at 10:28 PM, Gregory=
 Maxwell via bitcoin-dev <span dir=3D"ltr">&lt;<a href=3D"mailto:bitcoin-de=
v@lists.linuxfoundation.org" target=3D"_blank">bitcoin-dev@lists.linuxfound=
ation.org</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"><span cl=
ass=3D"">On Fri, Jun 2, 2017 at 2:15 AM, Chris via bitcoin-dev<br>
&lt;<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org">bitcoin-dev@li=
sts.<wbr>linuxfoundation.org</a>&gt; wrote:<br>
&gt; On 06/01/2017 06:10 PM, Olaoluwa Osuntokun via bitcoin-dev wrote:<br>
&gt;<br>
&gt;&gt; One aspect which isn&#39;t in this BIP draft is direct support for=
 unconfirmed<br>
&gt;&gt; transactions. I consider such a feature an important UX feature fo=
r mobile<br>
&gt;&gt; phones, and something which I&#39;ve personally seen as an importa=
nt<br>
&gt;&gt; UX-experience when on-boarding new users to Bitcoin.<br>
&gt;<br>
&gt; Totally agree. My first thought is maybe you could keep bip37 filterin=
g<br>
&gt; as optional for unconfirmed transactions. Since you&#39;re only intere=
sted<br>
<br>
</span>Really bad for privacy. Data for transactions at the tip is only<br>
14kb/s-- potentially less if segwit is in use and you&#39;re not getting<br=
>
witnesses. Is that really that burdensome?<br>
<br>
FWIW, leaving a mobile browser just running while pointed at some<br>
websites seems to use more traffic than that just loading advertising.<br>
:)<br>
<div class=3D"HOEnZb"><div class=3D"h5">______________________________<wbr>=
_________________<br>
bitcoin-dev mailing list<br>
<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org">bitcoin-dev@lists.=
<wbr>linuxfoundation.org</a><br>
<a href=3D"https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev" =
rel=3D"noreferrer" target=3D"_blank">https://lists.linuxfoundation.<wbr>org=
/mailman/listinfo/bitcoin-<wbr>dev</a><br>
</div></div></blockquote></div><br></div>

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