How to MarshalG2?

[doubiliu]

I'm using gnark to develop a project. I found that the method of MarshalG1 is provided in lib, but no related method of MarshalG2 is found. So how do I serialize G2?
@ivokub

[gbotrel]

Hey -- you can access serialization functions in gnark-crypto, for example here: https://pkg.go.dev/github.com/consensys/gnark-crypto/ecc/bn254#G2Affine.Marshal

or here:

https://pkg.go.dev/github.com/consensys/gnark-crypto/ecc/bn254#G2Affine.Bytes

[doubiliu]

Hey -- you can access serialization functions in gnark-crypto, for example here: https://pkg.go.dev/github.com/consensys/gnark-crypto/ecc/bn254#G2Affine.Marshal

or here:

https://pkg.go.dev/github.com/consensys/gnark-crypto/ecc/bn254#G2Affine.Bytes

I want to use in the circuit, crypto lib doesn't seem to work

[ivokub]

We currently don't have in-circuit implementation of G2 marshalling. The issue there is that G2 points use different towers depending on the curve and we would have to implement it per-curve. What particular curve you would be interested in?

[doubiliu]

We currently don't have in-circuit implementation of G2 marshalling. The issue there is that G2 points use different towers depending on the curve and we would have to implement it per-curve. What particular curve you would be interested in?

I think BN254 and BLS12381 are commonly used. We temporarily implemented a function in our local gnark library.

[ivokub]

Could you share the snippet you have it for BN254 or BLS12381? I'll have a look and if it looks good then I'll create a PR for that.

[txhsl]

Could you share the snippet you have it for BN254 or BLS12381? I'll have a look and if it looks good then I'll create a PR for that.

bane-labs@2940311. We simply add it to BLS12381, the idea is the same as MarshalG1, based on gnark-crypto. It can be a generic method, but we only need it in BLS12381.