Hi,
in go-ethereum[1], we use elliptic.{Unmarshal,Marshal} with the secp256k1 curve.
This curve is not strictly supported by package elliptic because it is a short weierstrass curve
with a=0 whereas the curves in package elliptic have a=-3.
CL 2421 changed elliptic.Unmarshal to verify that the point lies on the curve, but calls
IsOnCurve on CurveParams instead of using the method of the curve interface. This breaks
our use of Unmarshal because CurveParams.IsOnCurve assumes a=-3.
Would you accept a CL that changes elliptic.Unmarshal to call curve.IsOnCurve for Go 1.5,
or is it too late already?