How to authenticate the GKLocalPlayer on my 'third party server'?

Question

iOS7 introduced new GKLocalPlayer method generateIdentityVerificationSignatureWithCompletionHandler().

Does anyone know how to use it for good? I assum

Answer 1

Here is my implementation in Elixir.

def verify_login(player_id, public_key_url, timestamp, salt64, signature64, bundle_id) do
  salt = Base.decode64!(salt64)
  pay_load = <>
  pkey_cert = get_public_key_certificate(public_key_url)
  cert = :public_key.pkix_decode_cert(pkey_cert, :otp)
  case cert do
    {:OTPCertificate,
     {:OTPTBSCertificate, _, _, _, _, _, _,
      {:OTPSubjectPublicKeyInfo, _, key}, _, _, _}, _, _} ->
      signature = Base.decode64!(signature64)
      case :public_key.verify(pay_load, :sha256, signature, key) do
        true ->
          :ok
        false ->
          {:error, "apple login verify failed"}
      end
  end
end

def get_public_key_certificate(url) do
  case HTTPoison.get(url) do
    {:ok, %HTTPoison.Response{body: body}} ->
      body
  end
end