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Date: Fri, 25 Jul 2014 12:26:11 +0200
Message-ID: <CANEZrP0pMA=LB=Mi9xj9YbJ83=0r6Xa4_6Ua+wpAtsg5OdS7Kw@mail.gmail.com>
From: Mike Hearn <mike@plan99.net>
To: Aaron Voisine <voisine@gmail.com>
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Cc: "bitcoin-development@lists.sourceforge.net"
	<bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Time
Precedence: list

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Given that the speed at which the block chain advances is kind of
unpredictable, I'd think it might be better to just record the time to disk
when a PIN attempt is made and if you observe time going backwards, refuse
to allow more attempts until it's advanced past the previous attempt.


On Fri, Jul 25, 2014 at 7:56 AM, Aaron Voisine <voisine@gmail.com> wrote:

> It's based on the block height, not the block's timestamp. If you have
> access to the device and the phone itself is not pin locked, then you
> can jailbreak it and get access to the wallet seed that way. A pin
> locked device however is reasonably secure as the filesystem is
> hardware aes encrypted to a combination of pin+uuid. This was just an
> easy way to prevent multiple pin guesses by changing system time in
> settings, so that isn't the weakest part of the security model.
>
> Aaron Voisine
> breadwallet.com
>
>
> On Thu, Jul 24, 2014 at 8:21 PM, William Yager <will.yager@gmail.com>
> wrote:
> > On Thu, Jul 24, 2014 at 10:39 PM, Gregory Maxwell <gmaxwell@gmail.com>
> > wrote:
> >>
> >>
> >> Is breadwallet tamper resistant & zero on tamper hardware? otherwise
> >> this sounds like security theater.... I attach a debugger to the
> >> process (or modify the program) and ignore the block sourced time.
> >>
> >
> > It's an iOS application. I would imagine it is substantially more
> difficult
> > to attach to a process (which, at the very least, requires root, and
> perhaps
> > other things on iOS) than to convince the device to change its system
> time.
> >
> > That said, the security benefits might not be too substantial.
> >
> >
> ------------------------------------------------------------------------------
> > Want fast and easy access to all the code in your enterprise? Index and
> > search up to 200,000 lines of code with a free copy of Black Duck
> > Code Sight - the same software that powers the world's largest code
> > search on Ohloh, the Black Duck Open Hub! Try it now.
> > http://p.sf.net/sfu/bds
> > _______________________________________________
> > Bitcoin-development mailing list
> > Bitcoin-development@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/bitcoin-development
> >
>
>
> ------------------------------------------------------------------------------
> Want fast and easy access to all the code in your enterprise? Index and
> search up to 200,000 lines of code with a free copy of Black Duck
> Code Sight - the same software that powers the world's largest code
> search on Ohloh, the Black Duck Open Hub! Try it now.
> http://p.sf.net/sfu/bds
> _______________________________________________
> 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">Given that the speed at which the block chain advances is =
kind of unpredictable, I&#39;d think it might be better to just record the =
time to disk when a PIN attempt is made and if you observe time going backw=
ards, refuse to allow more attempts until it&#39;s advanced past the previo=
us attempt.</div>
<div class=3D"gmail_extra"><br><br><div class=3D"gmail_quote">On Fri, Jul 2=
5, 2014 at 7:56 AM, Aaron Voisine <span dir=3D"ltr">&lt;<a href=3D"mailto:v=
oisine@gmail.com" target=3D"_blank">voisine@gmail.com</a>&gt;</span> wrote:=
<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-lef=
t:1px #ccc solid;padding-left:1ex">
It&#39;s based on the block height, not the block&#39;s timestamp. If you h=
ave<br>
access to the device and the phone itself is not pin locked, then you<br>
can jailbreak it and get access to the wallet seed that way. A pin<br>
locked device however is reasonably secure as the filesystem is<br>
hardware aes encrypted to a combination of pin+uuid. This was just an<br>
easy way to prevent multiple pin guesses by changing system time in<br>
settings, so that isn&#39;t the weakest part of the security model.<br>
<span class=3D"HOEnZb"><font color=3D"#888888"><br>
Aaron Voisine<br>
<a href=3D"http://breadwallet.com" target=3D"_blank">breadwallet.com</a><br=
>
</font></span><div class=3D"HOEnZb"><div class=3D"h5"><br>
<br>
On Thu, Jul 24, 2014 at 8:21 PM, William Yager &lt;<a href=3D"mailto:will.y=
ager@gmail.com">will.yager@gmail.com</a>&gt; wrote:<br>
&gt; On Thu, Jul 24, 2014 at 10:39 PM, Gregory Maxwell &lt;<a href=3D"mailt=
o:gmaxwell@gmail.com">gmaxwell@gmail.com</a>&gt;<br>
&gt; wrote:<br>
&gt;&gt;<br>
&gt;&gt;<br>
&gt;&gt; Is breadwallet tamper resistant &amp; zero on tamper hardware? oth=
erwise<br>
&gt;&gt; this sounds like security theater.... I attach a debugger to the<b=
r>
&gt;&gt; process (or modify the program) and ignore the block sourced time.=
<br>
&gt;&gt;<br>
&gt;<br>
&gt; It&#39;s an iOS application. I would imagine it is substantially more =
difficult<br>
&gt; to attach to a process (which, at the very least, requires root, and p=
erhaps<br>
&gt; other things on iOS) than to convince the device to change its system =
time.<br>
&gt;<br>
&gt; That said, the security benefits might not be too substantial.<br>
&gt;<br>
</div></div><div class=3D"HOEnZb"><div class=3D"h5">&gt; ------------------=
------------------------------------------------------------<br>
&gt; Want fast and easy access to all the code in your enterprise? Index an=
d<br>
&gt; search up to 200,000 lines of code with a free copy of Black Duck<br>
&gt; Code Sight - the same software that powers the world&#39;s largest cod=
e<br>
&gt; search on Ohloh, the Black Duck Open Hub! Try it now.<br>
&gt; <a href=3D"http://p.sf.net/sfu/bds" target=3D"_blank">http://p.sf.net/=
sfu/bds</a><br>
&gt; _______________________________________________<br>
&gt; Bitcoin-development mailing list<br>
&gt; <a href=3D"mailto:Bitcoin-development@lists.sourceforge.net">Bitcoin-d=
evelopment@lists.sourceforge.net</a><br>
&gt; <a href=3D"https://lists.sourceforge.net/lists/listinfo/bitcoin-develo=
pment" target=3D"_blank">https://lists.sourceforge.net/lists/listinfo/bitco=
in-development</a><br>
&gt;<br>
<br>
---------------------------------------------------------------------------=
---<br>
Want fast and easy access to all the code in your enterprise? Index and<br>
search up to 200,000 lines of code with a free copy of Black Duck<br>
Code Sight - the same software that powers the world&#39;s largest code<br>
search on Ohloh, the Black Duck Open Hub! Try it now.<br>
<a href=3D"http://p.sf.net/sfu/bds" target=3D"_blank">http://p.sf.net/sfu/b=
ds</a><br>
_______________________________________________<br>
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>
</div></div></blockquote></div><br></div>

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