Re: Your help needed

Dear Bill,

>I assume you want to compute the order of a point on a elliptic curve
>over a finite field of size around 512bit.
>Unfortunately the number of points on the curve is too hard to be factored
>by PARI.

Yes, that's exactly what I want to do.

Is there any way to compute a 512-bit order?

Any comments are welcome!

Best regards,

Shin

On Mon, Jan 27, 2014 at 10:02 PM, Bill Allombert <Bill.Allombert@math.u-bordeaux1.fr> wrote:

On Mon, Jan 27, 2014 at 01:41:01PM +0900, SeongHan Shin wrote:
> Dear all,
>
> I have encountered with the following warning:
> ++++++++++++++++++ 512 bit +++++++++++++++++
> parisize = 500000000, primelimit = 500000
> *** ellorder: Warning: MPQS: number too big to be factored with MPQS,
> giving up.
>
> Could you please let me know how to get around this problem?

What do you want to do ?
I assume you want to compute the order of a point on a elliptic curve
over a finite field of size around 512bit.
Unfortunately the number of points on the curve is too hard to be factored
by PARI.

But maybe you have extra information about your problem that you can use.
So please tell us more about your computation.

Cheers,
Bill.

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SeongHan Shin
Research Institute for Secure Systems (RISEC),
National Institute of Advanced Industrial Science and Technology (AIST),
Central 2, 1-1-1, Umezono, Tsukuba City, Ibaraki 305-8568 Japan
Tel : +81-29-861-2670/5284
Fax : +81-29-861-5285
E-mail : seonghan.shin@aist.go.jp
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