Module ed_on_bls12_381_bandersnatch 

Ed-on-BLS12-381-Bandersnatch types and host functions.

Bandersnatch is an incomplete twisted Edwards curve: the HWCD add/double formulas can produce projective points with z = 0 when fed cofactor-admixed (non-prime-order-subgroup) inputs. Such points have no affine representative, so the standard (x || y) FFI channel cannot carry them: arkworks’ From<Projective> for Affine panics on z.inverse().unwrap().

The shared utils::mul_te / utils::msm_te helpers detect the degenerate case via utils::IntoAffineSafe and return utils::Error::DegeneratePoint across the FFI boundary instead of attempting to serialize an unrepresentable point. The runtime-side hooks defined in this module catch that error and substitute the all-zero projective point (0, 0, 0, 0): not a valid curve point and with z = 0 it has no affine representative, so any downstream validity or subgroup check on the result rejects it. The wire format stays byte-identical to ArkScale<EdwardsAffine>: no sentinel bit, no dedicated projective codec.

Modules

host_calls

Interfaces for working with Arkworks Ed-on-BLS12-381-Bandersnatch elliptic curve related types from within the runtime.

Structs

HostHooks

Curve hooks jumping into host_calls host functions.

Type Aliases

BandersnatchConfig

Group configuration.

EdwardsAffine

Twisted Edwards form point affine representation.

EdwardsConfig

Group configuration for Twisted Edwards form (equal to BandersnatchConfig).

EdwardsProjective

Twisted Edwards form point projective representation.

SWAffine

Short Weierstrass form point affine representation.

SWConfig

Group configuration for Short Weierstrass form (equal to BandersnatchConfig).

SWProjective

Short Weierstrass form point projective representation.

ScalarField

Group scalar field (Fr).