From: Peter Todd <pete@petertodd•org>
To: Gregory Maxwell <gmaxwell@gmail•com>
Cc: Bitcoin Development <bitcoin-development@lists•sourceforge.net>
Subject: Re: [Bitcoin-development] New side channel attack that can recover Bitcoin keys
Date: Wed, 12 Mar 2014 05:44:24 -0400 [thread overview]
Message-ID: <20140312094424.GD15281@savin> (raw)
In-Reply-To: <CAAS2fgRTuOaSbTqnCOp=783gLCeh7ZU0FWbxzMS6pe8WKPTcLQ@mail.gmail.com>
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On Wed, Mar 05, 2014 at 12:54:04PM -0800, Gregory Maxwell wrote:
> On Wed, Mar 5, 2014 at 12:32 PM, Peter Todd <pete@petertodd•org> wrote:
> > That's nice, but I wrote my advice to show people how even if they don't
> > know any crypto beyond what the "black boxes" do - the absolute minimum
> > you need to know to write any Bitcoin software - you can still defend
> > yourself against that attack and many others.
>
> But it's still incomplete.
>
> Say you have an address— used only once!— with a txout with a lot of value.
>
> Someone starts paying you small amounts to that address over and over
> again. You haven't asked them to, they're just doing it.
>
> Do you ignore the funds?— maybe tell some customer that was ignorantly
> paying you over and over again to a single address "sorry, those are
> my rules: I only acknowledge the first payment, those funds are
> lost!".
>
> No, of course not. You spend the darn coins and if you're on a shared
> host perhaps you disclose a private key.
>
> The probability of an attack actually going on is low enough compared
> to the cost of spending the coins in that case that even someone with
> good knoweldge of the risks will choose to do so.
>
> So absolutely, not reusing addresses massively increases your safety
> and limits losses when there is theft. But it isn't enough alone. (Nor
> is smarter signing, considering complex software like this has bugs
> and its hard to be confident that something is side channel free— esp
> when you allow attacker interference).
I think you're misunderstanding me: I'm assuming one of the n parties
signing transactions in my multi-factor authentication scheme is
uncompromised - much easier to do when it's a low-bandwidth box sitting
in a secure location.
Not re-using keys is nice too of course, and while not perfect - your
above scenario - certainely helps limit losses.
--
'peter'[:-1]@petertodd.org
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next prev parent reply other threads:[~2014-03-12 9:44 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-05 12:49 Mike Hearn
2014-03-05 12:56 ` Pieter Wuille
2014-03-05 13:18 ` Jean-Paul Kogelman
2014-03-05 14:04 ` Pieter Wuille
2014-03-05 16:21 ` Kevin
2014-03-05 19:39 ` Peter Todd
2014-03-05 19:51 ` Gregory Maxwell
2014-03-05 20:32 ` Peter Todd
2014-03-05 20:54 ` Gregory Maxwell
2014-03-12 9:44 ` Peter Todd [this message]
2014-03-05 22:17 ` James Hartig
2014-03-05 22:26 ` Eric Lombrozo
2014-03-06 7:02 ` Odinn Cyberguerrilla
2014-03-08 19:34 ` Luke-Jr
2014-03-09 1:57 ` Gregory Maxwell
2014-03-05 21:31 ` Eric Lombrozo
2014-03-05 21:44 ` Gregory Maxwell
2014-03-05 22:14 ` Eric Lombrozo
2014-03-05 22:25 ` Gregory Maxwell
2014-03-06 8:38 ` Mike Hearn
2014-03-06 10:00 ` Natanael
2014-03-25 13:39 ` Troy Benjegerdes
2014-03-25 13:50 ` Gavin Andresen
2014-03-08 19:29 ` Gustav Simonsson
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