Official discussion thread for LostKey. Please do not post any spoilers or big hints.

So I know what the program is, but just not how to crack it.

What curve is that? Iâ€™ve scoured wiki and EFD to no avail.

Iâ€™ve found implementation bug (?) and the assertion says nothing about the the field order either.

Any hints?

A pretty good, fun challenge! Harder than I expected, but I learnt a lot on the way. Without giving away too much, you need to work out the curve, itâ€™s not your typical EC. Then SageMath is your friendâ€¦

Need some help here, I found nothing interesting in the python code until nowâ€¦

Type your comment> @Agatuz1 said:

Need some help here, I found nothing interesting in the python code until nowâ€¦

Have you worked out the curve yet?

Type your comment> @jack0 said:

Type your comment> @Agatuz1 said:

Need some help here, I found nothing interesting in the python code until nowâ€¦

Have you worked out the curve yet?

Yes, I found the curve parameters, and found the y coord for the Gn. but now I am totally stuck.

Can I PM you?

Such a great challenge! Thanks @R4J! Thanks to @jack0 for the nudge!

If anyone needs a small hint or a sanity check they can send me a pm!

Type your comment> @Agatuz1 said:

Yes, I found the curve parameters, and found the y coord for the Gn. but now I am totally stuck.

Can I PM you?

Sure

Oh man, this is my new favorite challenge. Thanks to ArtemisFY and jack0 for the nudges, and sampriti for creating it. I knew nothing about ECC or sage before starting this, and it was a very educational journey. Andrea Corbelliniâ€™s blog has a good â€śgentle introductionâ€ť to the field if you are starting from nothing. The Hankerson, Menezes, and Vanstone textbook is more comprehensive. Feel free to PM for nudges, and Merry Christmas, everybody.

I think Iâ€™ve got the correct parameters and some candidates for Gn_y.

Iâ€™ve tried doing it in sage but my machine hanged. An elementary algorithm will likely meet memory bounds as well.

Can I PM you for a sanity check and further clues?

Hi NaN, sure, youâ€™re welcome to PM me with what you have so far for a sanity check

Cheers

Got it with great helps from jack0. This is my first ECC-related challenge and I learned something there.

As a little hint: If youâ€™re a beginner like me you need to check whatâ€™s needed for a secure curve and compare whatâ€™s wrong with this one.