[147582] in cryptography@c2.net mail archive
Re: [Cryptography] Elliptic curve question
daemon@ATHENA.MIT.EDU (Phillip Hallam-Baker)
Wed Oct 9 22:16:27 2013
X-Original-To: cryptography@metzdowd.com
In-Reply-To: <525467B9.30501@echeque.com>
Date: Wed, 9 Oct 2013 21:01:05 -0400
From: Phillip Hallam-Baker <hallam@gmail.com>
To: "James A. Donald" <jamesd@echeque.com>
Cc: "cryptography@metzdowd.com" <cryptography@metzdowd.com>
Errors-To: cryptography-bounces+crypto.discuss=bloom-picayune.mit.edu@metzdowd.com
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On Tue, Oct 8, 2013 at 4:14 PM, James A. Donald <jamesd@echeque.com> wrote:
> On 2013-10-08 03:14, Phillip Hallam-Baker wrote:
>
>
> Are you planning to publish your signing key or your decryption key?
>
> Use of a key for one makes the other incompatible.=EF=BF=BD
>
>
> Incorrect. One's public key is always an elliptic point, one's private
> key is always a number.
>
> Thus there is no reason in principle why one cannot use the same key (a
> number) for signing the messages you send, and decrypting the messages yo=
u
> receive.
>
The original author was proposing to use the same key for encryption and
signature which is a rather bad idea.
--=20
Website: http://hallambaker.com/
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<div dir=3D"ltr"><br><div class=3D"gmail_extra"><br><br><div class=3D"gmail=
_quote">On Tue, Oct 8, 2013 at 4:14 PM, James A. Donald <span dir=3D"ltr">&=
lt;<a href=3D"mailto:jamesd@echeque.com" target=3D"_blank">jamesd@echeque.c=
om</a>></span> wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex">
=20
=20
=20
<div bgcolor=3D"#FFFFFF" text=3D"#000000"><div class=3D"im">
<div>On 2013-10-08 03:14, Phillip
Hallam-Baker wrote:<br>
</div>
</div><blockquote type=3D"cite">
=20
<div dir=3D"ltr">
<div class=3D"gmail_extra">
<div class=3D"gmail_quote"><div class=3D"im"><br>
<div>Are you planning to publish your signing key or your
decryption key?</div>
<div><br>
</div>
</div><div>Use of a key for one makes the other incompatible.=
=EF=BF=BD<br>
</div>
</div>
</div>
</div>
</blockquote>
<br>
Incorrect.=C2=A0 One's public key is always an elliptic point, one&=
#39;s
private key is always a number.=C2=A0 <br>
<br>
Thus there is no reason in principle why one cannot use the same key
(a number) for signing the messages you send, and decrypting the
messages you receive.<br></div></blockquote><div><br></div><div>=C2=A0T=
he original author was proposing to use the same key for encryption and sig=
nature which is a rather bad idea.</div><div><br></div><div><br></div><div>
<br></div></div>-- <br>Website: <a href=3D"http://hallambaker.com/">http://=
hallambaker.com/</a><br>
</div></div>
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