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From: Edmund Edgar <ed@realitykeys.com>
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Subject: Re: [Bitcoin-development] Is this a safe thing to be doing with ECC
addition? (Oracle protocol)
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--047d7b6783f6690f9504f4147a74
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On 8 March 2014 17:10, Alan Reiner <etotheipi@gmail.com> wrote:
> I create a new keypair, <c_pub> with <c_priv> which I know (it can be any
> arbitrary key pair). But I don't give you <c_pub>, I give you <b_pub> =
> <c_pub> minus <a_pub> (which I can do because I've seen <a_pub> before
> doing this).
>
> Sure, I don't know the private key for <b_pub>, but it doesn't matter...
> because what
>
> <b_pub> + <a_pub> = <c_pub> (mine)
>
> You have no way to detect this condition, because you don't know what
> c_pub/c_priv I created, so you can only detect this after it's too late
> (after I abuse the private key)
>
Thanks Alan and Forrest, that makes sense. So to salvage the situation in
the original case, we have to make sure the parties exchange their public
keys first, before they're allowed to see the public keys they'll be
combining them with.
--
--
Edmund Edgar
Founder, Social Minds Inc (KK)
Twitter: @edmundedgar
Linked In: edmundedgar
Skype: edmundedgar
http://www.socialminds.jp
Reality Keys
@realitykeys
ed@realitykeys.com
https://www.realitykeys.com
--047d7b6783f6690f9504f4147a74
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
<div dir=3D"ltr"><div class=3D"gmail_extra"><div class=3D"gmail_quote">On 8=
March 2014 17:10, Alan Reiner <span dir=3D"ltr"><<a href=3D"mailto:etot=
heipi@gmail.com" target=3D"_blank">etotheipi@gmail.com</a>></span> wrote=
:<br><div>
=C2=A0</div><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;bo=
rder-left:1px #ccc solid;padding-left:1ex"><div bgcolor=3D"#FFFFFF" text=3D=
"#000000">
I create a new keypair, <c_pub> with <c_priv> which I
know (it can be any arbitrary key pair).=C2=A0 But I don't give you
<c_pub>, I give you=C2=A0 <b_pub> =3D <c_pub> minus
<a_pub> (which I can do because I've seen <a_pub> befor=
e
doing this).=C2=A0 <br>
<br>
Sure, I don't know the private key for <b_pub>, but it doesn&=
#39;t
matter... because what <br>
<br>
<b_pub> + <a_pub> =3D <c_pub> (mine)<br>
<br>
You have no way to detect this condition, because you don't know
what c_pub/c_priv I created, so you can only detect this after it's
too late (after I abuse the private key)</div></blockquote><div><br></d=
iv><div>Thanks Alan and Forrest, that makes sense. So to salvage the situat=
ion in the original case, we have to make sure the parties exchange their p=
ublic keys first, before they're allowed to see the public keys they=
9;ll be combining them with.=C2=A0</div>
</div><div><br></div>-- <br><div dir=3D"ltr"><div>--=C2=A0</div><div>Edmund=
Edgar</div><div>Founder, Social Minds Inc (KK)</div><div>Twitter: @edmunde=
dgar</div><div>Linked In: edmundedgar</div><div>Skype: edmundedgar</div><di=
v><a href=3D"http://www.socialminds.jp" target=3D"_blank">http://www.social=
minds.jp</a></div>
<div><br></div><div>Reality Keys</div><div>@realitykeys</div><div><a href=
=3D"mailto:ed@realitykeys.com" target=3D"_blank">ed@realitykeys.com</a></di=
v><div><a href=3D"https://www.realitykeys.com" target=3D"_blank">https://ww=
w.realitykeys.com</a></div>
</div>
</div></div>
--047d7b6783f6690f9504f4147a74--
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