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From: Eric Lombrozo <elombrozo@gmail.com>
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To: James Hartig <fastest963@gmail.com>
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Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] New side channel attack that can recover
	Bitcoin keys
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Oh, I absolutely agree that this type of attack is NOT the weakest link =
in security. There are MANY far easier targets in bitcoind and typical =
use scenarios of it. If we want to dramatically improve the security of =
a typical bitcoin wallet, the FLUSH+RELOAD attack is probably not where =
our efforts would be best rewarded trying to prevent.

However, this thread IS about this particular attack vector - and my =
suggestion IS specific to this thread.

-Eric Lombrozo


On Mar 5, 2014, at 2:17 PM, James Hartig <fastest963@gmail.com> wrote:

> On Wed, Mar 5, 2014 at 2:39 PM, Peter Todd <pete@petertodd.org> wrote:
> > More important though is you shouldn't be using single factor =
Bitcoin
> > addresses. Use n-of-m multisig instead and architect your system =
such
> > that that every transaction that happens in your service has to be
> > authorized by both the "online" server(s) that host your website as =
well
> > as a second "hardened" server with an extremely limited interface
> > between it and the online server.
>=20
> This adds a very minor amount of security, if any, if someone manages =
to hack into your "hot wallet" server they can just initiate a =
non-multisig transaction and still steal all your bitcoins in that =
wallet. You can't give the argument that the RPC API is password =
protected because the password is stored in plain-text in the config so =
all someone has to do is first grep for the file. There doesn't appear =
to be a way to force ALL outgoing transactions to be multisig and even =
if there was one, would you be able to force one of the addresses to be =
the "hardened" server? That still wouldn't prevent anyone from just =
stopping bitcoind, changing the config, then restarting it.
>=20
> Unless you're using your own custom wallet software there doesn't seem =
to be any sufficient way to prevent someone from stealing all your money =
once they have access to your server. Other software, like MySQL has =
access controls so I can prevent ALTERs, DROPs, DELETEs, etc for all =
"live" accounts limiting the scope of any attack if they manage to get =
into the server. Maybe this is beyond the scope of bitcoind, not sure.
>=20
> Thanks,
> --
> James Hartig
> Software Engineer @ Grooveshark.com
> http://twitter.com/jameshartig
> =
--------------------------------------------------------------------------=
----
> Subversion Kills Productivity. Get off Subversion & Make the Move to =
Perforce.
> With Perforce, you get hassle-free workflows. Merge that actually =
works.=20
> Faster operations. Version large binaries.  Built-in WAN optimization =
and the
> freedom to use Git, Perforce or both. Make the move to Perforce.
> =
http://pubads.g.doubleclick.net/gampad/clk?id=3D122218951&iu=3D/4140/ostg.=
clktrk_______________________________________________
> Bitcoin-development mailing list
> Bitcoin-development@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/bitcoin-development


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<html><head><meta http-equiv=3D"Content-Type" content=3D"text/html =
charset=3Dus-ascii"></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Oh, I =
absolutely agree that this type of attack is NOT the weakest link in =
security. There are MANY far easier targets in bitcoind and typical use =
scenarios of it. If we want to dramatically improve the security of a =
typical bitcoin wallet, the FLUSH+RELOAD attack is probably not where =
our efforts would be best rewarded trying to =
prevent.<div><br></div><div>However, this thread IS about this =
particular attack vector - and my suggestion IS specific to this =
thread.</div><div><br></div><div>-Eric =
Lombrozo</div><div><div><br></div><div><br><div><div>On Mar 5, 2014, at =
2:17 PM, James Hartig &lt;<a =
href=3D"mailto:fastest963@gmail.com">fastest963@gmail.com</a>&gt; =
wrote:</div><br class=3D"Apple-interchange-newline"><blockquote =
type=3D"cite"><div dir=3D"ltr">On Wed, Mar 5, 2014 at 2:39 PM, Peter =
Todd&nbsp;<span dir=3D"ltr">&lt;<a href=3D"mailto:pete@petertodd.org" =
target=3D"_blank">pete@petertodd.org</a>&gt;</span>&nbsp;wrote:<div><div>&=
gt; More important though is you shouldn't be using single factor =
Bitcoin</div>

<div>&gt; addresses. Use n-of-m multisig instead and architect your =
system such</div><div>&gt; that that every transaction that happens in =
your service has to be</div><div>&gt; authorized by both the "online" =
server(s) that host your website as well</div>

<div>&gt; as a second "hardened" server with an extremely limited =
interface</div><div>&gt; between it and the online server.</div><div =
class=3D"gmail_extra"><br></div><div class=3D"gmail_extra">This adds a =
very minor amount of security, if any, if someone manages to hack into =
your "hot wallet" server they can just initiate a non-multisig =
transaction and still steal all your bitcoins in that wallet. You can't =
give the argument that the RPC API is password protected because the =
password is stored in plain-text in the config so all someone has to do =
is first grep for the file. There doesn't appear to be a way to force =
ALL outgoing transactions to be multisig and even if there was one, =
would you be able to force one of the addresses to be the "hardened" =
server? That still wouldn't prevent anyone from just stopping bitcoind, =
changing the config, then restarting it.</div>

<div class=3D"gmail_extra"><br></div><div class=3D"gmail_extra">Unless =
you're using your own custom wallet software there doesn't seem to be =
any sufficient way to prevent someone from stealing all your money once =
they have access to your server. Other software, like MySQL has access =
controls so I can prevent ALTERs, DROPs, DELETEs, etc for all "live" =
accounts limiting the scope of any attack if they manage to get into the =
server. Maybe this is beyond the scope of bitcoind, not sure.</div>

<div class=3D"gmail_extra"><br clear=3D"all"><div><div =
dir=3D"ltr">Thanks,<br>--<br>James Hartig<br>Software Engineer @ <a =
href=3D"http://Grooveshark.com">Grooveshark.com</a><br><a =
href=3D"http://twitter.com/jameshartig" =
target=3D"_blank">http://twitter.com/jameshartig</a></div>

</div></div></div></div>
=
--------------------------------------------------------------------------=
----<br>Subversion Kills Productivity. Get off Subversion &amp; Make the =
Move to Perforce.<br>With Perforce, you get hassle-free workflows. Merge =
that actually works. <br>Faster operations. Version large binaries. =
&nbsp;Built-in WAN optimization and the<br>freedom to use Git, Perforce =
or both. Make the move to Perforce.<br><a =
href=3D"http://pubads.g.doubleclick.net/gampad/clk?id=3D122218951&amp;iu=3D=
/4140/ostg.clktrk_______________________________________________">http://p=
ubads.g.doubleclick.net/gampad/clk?id=3D122218951&amp;iu=3D/4140/ostg.clkt=
rk_______________________________________________</a><br>Bitcoin-developme=
nt mailing =
list<br>Bitcoin-development@lists.sourceforge.net<br>https://lists.sourcef=
orge.net/lists/listinfo/bitcoin-development<br></blockquote></div><br></di=
v></div></body></html>=

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