[147590] in cryptography@c2.net mail archive
Re: [Cryptography] Elliptic curve question
daemon@ATHENA.MIT.EDU (=?UTF-8?Q?Lodewijk_andr=C3=A9_de_l)
Thu Oct 10 15:17:07 2013
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In-Reply-To: <CAMm+LwjoqFEmYbz+LzDY9dV1ti=6PMByyL+S1h018z_dAPDFjA@mail.gmail.com>
From: =?UTF-8?Q?Lodewijk_andr=C3=A9_de_la_porte?= <l@odewijk.nl>
Date: Thu, 10 Oct 2013 10:10:40 +0200
To: Phillip Hallam-Baker <hallam@gmail.com>
Cc: "cryptography@metzdowd.com" <cryptography@metzdowd.com>,
"James A. Donald" <jamesd@echeque.com>
Errors-To: cryptography-bounces+crypto.discuss=bloom-picayune.mit.edu@metzdowd.com
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2013/10/10 Phillip Hallam-Baker <hallam@gmail.com>
> The original author was proposing to use the same key for encryption and
> signature which is a rather bad idea.
>
Explain why, please. It might expand the attack surface, that's true. You
could always add a signed message that says "I used a key named 'Z' for
encryption here". Would that solve the problem?
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<div dir=3D"ltr"><div class=3D"gmail_extra">2013/10/10 Phillip Hallam-Baker=
<span dir=3D"ltr"><<a href=3D"mailto:hallam@gmail.com" target=3D"_blank=
">hallam@gmail.com</a>></span><br><div class=3D"gmail_quote"><blockquote=
class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc soli=
d;padding-left:1ex">
<div>=C2=A0The original author was proposing to use the same key for encryp=
tion and signature which is a rather bad idea.</div><span class=3D"HOEnZb">=
<font color=3D"#888888"><div></div></font></span></blockquote></div><br>Exp=
lain why, please. It might expand the attack surface, that's true. You =
could always add a signed message that says "I used a key named 'Z=
' for encryption here". Would that solve the problem?</div>
</div>
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