I'm attempting to sign JWT using ES256 algorithm. I found decent code samples and tutorials, however when trying to run them I get the following error:

The specified key parameters are not valid. Q.X and Q.Y are required fields. Q.X, Q.Y must be the same length. If D is specified it must be the same length as Q.X and Q.Y for named curves or the same length as Order for explicit curves.

The code I came up with from misc. sources can be found in this gist.

I'm quite fresh to C# so pardon any beginner mistakes and teach me!

Also I can't use the Cng library because it's not supported on AWS Lambda where I'm trying to run the signing handler.