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<H1>[zapps-wg] Powers of Tau Attestation</H1>
<B>Sean Bowe</B>
<A HREF="mailto:zapps-wg%40lists.zfnd.org?Subject=Re%3A%20%5Bzapps-wg%5D%20Powers%20of%20Tau%20Attestation&In-Reply-To=%3CCAKazn3%3D5ZgQvdv8CrQt54SPqoykB-N2fmhv1PQm8H-6haSjUyg%40mail.gmail.com%3E"
TITLE="[zapps-wg] Powers of Tau Attestation">sean at z.cash
</A><BR>
<I>Mon Jan 22 06:56:15 EST 2018</I>
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<PRE>There are potentially few useful entropy sources on an isolated system with
its peripherals removed that has just booted (for example), so a cat
walking across the keyboard can be used to strengthen the randomness at
little cost. It's mostly defense-in-depth.
Sean
On Mon, Jan 22, 2018 at 1:59 AM, Bastien Teinturier via zapps-wg &lt;
<A HREF="/mailman/listinfo/zapps-wg">zapps-wg at lists.z.cash.foundation</A>&gt; wrote:
&gt;<i> It's a good point, and I was wondering why this &quot;manual input&quot; entropy is
</I>&gt;<i> needed.
</I>&gt;<i> I don't understand what it adds to the entropy implicitly grabbed from the
</I>&gt;<i> system by the executable.
</I>&gt;<i> If we assume that an adversary is able to monitor the system and replicate
</I>&gt;<i> the entropy of the random generator used in the code, that adversary is
</I>&gt;<i> probably able to grab the input to the process as well right?
</I>&gt;<i> I'm interested in learning more about why you felt it was necessary to ask
</I>&gt;<i> the user to provide some random input.
</I>&gt;<i>
</I>&gt;<i> Cheers,
</I>&gt;<i> Bastien
</I>&gt;<i>
</I>&gt;<i> On Sat, Jan 20, 2018 at 2:04 PM, Daira Hopwood via zapps-wg &lt;
</I>&gt;<i> <A HREF="/mailman/listinfo/zapps-wg">zapps-wg at lists.z.cash.foundation</A>&gt; wrote:
</I>&gt;<i>
</I>&gt;&gt;<i> On 18/01/18 13:46, Bastien Teinturier via zapps-wg wrote:
</I>&gt;&gt;<i> &gt; Powers of Tau Attestation
</I>&gt;&gt;<i>
</I>&gt;&gt;<i> Notice that PowersOfTau_2.jpg leaks the additional entropy provided
</I>&gt;&gt;<i> to the computation. That's ok, it uses operating system entropy as
</I>&gt;&gt;<i> well; just noting that future participants might want to avoid that.
</I>&gt;&gt;<i>
</I>&gt;&gt;<i> --
</I>&gt;&gt;<i> Daira Hopwood &#9895;&#9398;
</I>&gt;&gt;<i>
</I>&gt;&gt;<i>
</I>&gt;<i>
</I>&gt;<i>
</I>&gt;<i> --
</I>&gt;<i>
</I>&gt;<i> [image: stratumn-logo.jpg]
</I>&gt;<i>
</I>&gt;<i>
</I>&gt;<i> Bastien Teinturier
</I>&gt;<i>
</I>&gt;<i> Senior Software Engineer
</I>&gt;<i>
</I>&gt;<i> Stratumn SAS, 1 bis Cit&#233; Paradis, 75010 Paris, France
</I>&gt;<i>
</I>&gt;<i> +33 6 28 57 71 59 &lt;+33%206%2028%2057%2071%2059&gt; &#8226; <A HREF="/mailman/listinfo/zapps-wg">bastien at stratumn.com</A> &#8226;
</I>&gt;<i> stratumn.com &lt;<A HREF="https://stratumn.com/careers">https://stratumn.com/careers</A>&gt;
</I>&gt;<i>
</I>&gt;<i> We are hiring &lt;<A HREF="https://stratumn.com/careers">https://stratumn.com/careers</A>&gt; &#8226; Read about us
</I>&gt;<i> &lt;<A HREF="http://blog.stratumn.com">http://blog.stratumn.com</A>&gt; &#8226; Twitter &lt;<A HREF="https://twitter.com/stratumnhq">https://twitter.com/stratumnhq</A>&gt;
</I>&gt;<i>
</I>
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