For example, with openssl I have seen that facebook works with ANSI X9.62 prime256v1 elliptic curve and what I want is the point of the curve that is using with my signature. I have seen that I can extract the point from facebook certificate, in the public key.
So again with openssl I get the public key:
-----BEGIN PUBLIC KEY----- MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEoPGMr6c5iGhbE1YOFRW0p0XvG8fl hTwrBNRlijExIuqjku1knbplgeO2EnbYswtF8f8KKBScT9xzqbNJLaB20w== -----END PUBLIC KEY-----
But now I don't know how to get it. Anyone knows how to do it? Or am I doing it wrong? I can do operations with Sage.