New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Use the complete formulas for point doubling and addition #297

Open

tomato42 opened this issue Jun 1, 2022 · 1 comment

Labels

feature

Milestone

Member

tomato42 commented Jun 1, 2022

https://safecurves.cr.yp.to/ is outdated, there are complete point addition and doubling formulas: https://eprint.iacr.org/2015/1060 we should use them to protect against bugs in special case handling

tomato42 added the feature label

tomato42 added this to the someday/future milestone

mratsim commented Jan 29, 2023

I see that you use Jacobian coordinates.

You can also use conditional copies to select between add and doubles:

Derivation of efficient formulas:
- write-up: https://github.com/mratsim/constantine/blob/495ef44/constantine/math/elliptic/ec_shortweierstrass_jacobian.md
- impl: https://github.com/mratsim/constantine/blob/495ef449/constantine/math/elliptic/ec_shortweierstrass_jacobian.nim#L162-L334

And for projective coordinates complete formulas:

https://github.com/mratsim/constantine/blob/495ef44/constantine/math/elliptic/ec_shortweierstrass_projective.nim#L153-L406
(Note: Since I only configured secp256k1 and pairing-firnedly curve I only implemented the case where a==0 in the curve y² = x³+ax+b)

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment