From: Rainer Urian on
Hello,

are elliptic curves of the form
y^2 = x^3+ x*a over GF(p) , p > 3, prime
usable for cryptography or is it unsafe to use such a curve?

Thanks,
Rainer


From: Richard Herring on
In message <hj55tm$81g$00$1(a)news.t-online.com>, Rainer Urian
<rainer(a)urian.eu> writes
>Hello,
>
>are elliptic curves of the form y^2 = x^3+ x*a over GF(p) , p > 3,
>prime
>usable

Certainly. There are plenty of references in the literature (e.g. with
a=1 it's Barreto et al's "cryptographically interesting" curve E_1,0.)
But "usable" for what, exactly? ...

> for cryptography or is it unsafe to use such a curve?

.... "Cryptography" is a huge field and concepts like "usable" and
"unsafe" are ill-defined. You'd need to ask a much more specific
question to get a meaningful answer.

For instance, there are pairing-based attacks on supersingular curves
(bad), but the existence of those same pairings facilitates a whole new
class of identity-based systems (good (if that's what you need) ;-).

--
Richard Herring
From: Rainer Urian on
ok,
I meant secure for ECDH and ECDSA algorithm

"Richard Herring" <junk@[127.0.0.1]> schrieb im Newsbeitrag
news:6ij2VRHY6tVLFwqu(a)baesystems.com...
> In message <hj55tm$81g$00$1(a)news.t-online.com>, Rainer Urian
> <rainer(a)urian.eu> writes
>>Hello,
>>
>>are elliptic curves of the form y^2 = x^3+ x*a over GF(p) , p > 3, prime
>>usable
>
> Certainly. There are plenty of references in the literature (e.g. with a=1
> it's Barreto et al's "cryptographically interesting" curve E_1,0.) But
> "usable" for what, exactly? ...
>
>> for cryptography or is it unsafe to use such a curve?
>
> ... "Cryptography" is a huge field and concepts like "usable" and "unsafe"
> are ill-defined. You'd need to ask a much more specific question to get a
> meaningful answer.
>
> For instance, there are pairing-based attacks on supersingular curves
> (bad), but the existence of those same pairings facilitates a whole new
> class of identity-based systems (good (if that's what you need) ;-).
>
> --
> Richard Herring

From: Tadek on
Standards for Efficient Cryptography Group (SECG) published a document
called Recommended Elliptic Curve Domain Parameters:
http://www.secg.org/download/aid-386/sec2_final.pdf
These parameters/curves are safe to use and efficient.
Regards
T

On Jan 20, 8:14 pm, "Rainer Urian" <rai...(a)urian.eu> wrote:
> ok,
> I meant secure for ECDH and ECDSA algorithm
>
> "Richard Herring" <junk@[127.0.0.1]> schrieb im Newsbeitragnews:6ij2VRHY6tVLFwqu(a)baesystems.com...
>
> > In message <hj55tm$81g$0...(a)news.t-online.com>, Rainer Urian
> > <rai...(a)urian.eu> writes
> >>Hello,
>
> >>are elliptic curves of the form y^2 = x^3+ x*a  over GF(p) , p > 3, prime
> >>usable
>
> > Certainly. There are plenty of references in the literature (e.g. with a=1
> > it's Barreto et al's "cryptographically interesting" curve E_1,0.) But
> > "usable" for what, exactly? ...
>
> >> for cryptography or is it unsafe to use such a curve?
>
> > ... "Cryptography" is a huge field and concepts like "usable" and "unsafe"
> > are ill-defined. You'd need to ask a much more specific question to get a
> > meaningful answer.
>
> > For instance, there are pairing-based attacks on supersingular curves
> > (bad), but the existence of those same pairings facilitates a whole new
> > class of identity-based systems (good (if that's what you need) ;-).
>
> > --
> > Richard Herring

From: Rainer Urian on
Thank you for the answer I didn't ask the question :-)
I know the standardized secure curves very well.

But thats not the point.
Actually, the problem is as follows:
There exists a ECC test specifiction for smartcards which wants to test that
the smartcard should reject a ECC public key of the form (0,0).
Now I wonder if this is a useful test or not.
Such a point can only occure on curves of the form y^2 = x^3 + a*x



"Tadek" <tstruk(a)gmail.com> schrieb im Newsbeitrag
news:233846db-5fe5-42bb-8104-430e5da85b70(a)p8g2000yqb.googlegroups.com...
Standards for Efficient Cryptography Group (SECG) published a document
called Recommended Elliptic Curve Domain Parameters:
http://www.secg.org/download/aid-386/sec2_final.pdf
These parameters/curves are safe to use and efficient.
Regards
T

On Jan 20, 8:14 pm, "Rainer Urian" <rai...(a)urian.eu> wrote:
> ok,
> I meant secure for ECDH and ECDSA algorithm
>
> "Richard Herring" <junk@[127.0.0.1]> schrieb im
> Newsbeitragnews:6ij2VRHY6tVLFwqu(a)baesystems.com...
>
> > In message <hj55tm$81g$0...(a)news.t-online.com>, Rainer Urian
> > <rai...(a)urian.eu> writes
> >>Hello,
>
> >>are elliptic curves of the form y^2 = x^3+ x*a over GF(p) , p > 3, prime
> >>usable
>
> > Certainly. There are plenty of references in the literature (e.g. with
> > a=1
> > it's Barreto et al's "cryptographically interesting" curve E_1,0.) But
> > "usable" for what, exactly? ...
>
> >> for cryptography or is it unsafe to use such a curve?
>
> > ... "Cryptography" is a huge field and concepts like "usable" and
> > "unsafe"
> > are ill-defined. You'd need to ask a much more specific question to get
> > a
> > meaningful answer.
>
> > For instance, there are pairing-based attacks on supersingular curves
> > (bad), but the existence of those same pairings facilitates a whole new
> > class of identity-based systems (good (if that's what you need) ;-).
>
> > --
> > Richard Herring