I am currently trying to create an ECCCurve for E-521. Unfortunately, it is not currently a named curve in the library I am using, so I will have to define it manually.
I am using the definition of the E-521 curve provided here:
E521 is a curve over GF(2^521-1), formula x^2+y^2=1-376014x^2y^2, basepoint (1571054894184995387535939749894317568645297350402905821437625 18115230499438118852963259119606760410077267392791511426719338990 5003276673749012051148356041324, 12), order 2^519 - 3375547632585017057891076304187826360719049612140512266186351500 85779108655765, cofactor 4.
The two curve definitions I can choose from are FpCurve and F2mCurve. I'm not sure which one to choose for this. I have looked here. Unfortunately, I don't know how to extrapolate which one to use based just on the knowledge that E-521 is an Edwards curve.
Is an Edwards curve not compatible with the base classes that are defined in the library? Do I need to wait for further development there, or can I risk attempting to implement it myself? The latter is obviously a question I will likely have to answer myself, but some extra information on the risks/other implementations I could examine would be helpful.