How to add a new curve?

[doubiliu]

I need to use secp256r1 for signature verification, how can I add correlation curves in gnark library?

[ivokub]

Do you want to add a separate backend for secp256r1? I don't think its possible, for PLONK and Groth16 we need the elliptic curves to have high 2-adicity for some operations.

If you want to check the signatures using non-native arithmetic, then we already have it implemented: https://pkg.go.dev/github.com/consensys/gnark@v0.13.0/std/math/emulated/emparams#P256Fp. See also https://github.com/Consensys/gnark/blob/master/std/signature/ecdsa/ecdsa_secpr_test.go