class Acme::Client::JWK::ECDSA

def initialize(private_key)
  unless private_key.is_a?(OpenSSL::PKey::EC)
    raise ArgumentError, 'private_key must be a OpenSSL::PKey::EC'
  end
  unless @curve_params = KNOWN_CURVES[private_key.group.curve_name]
    raise ArgumentError, 'Unknown EC curve'
  end
  @private_key = private_key
end