Voxel Busters Essential Kit Game Services Server Auth on iOS

GameServicesExternalAuth.cs

public void LoadServerCredentials()
{
GameServices.LoadServerCredentials((result, error) =>
                    {
                        if(error == null)
                        {
                            StartCoroutine(VerifyIosServerCredentials(result.ServerCredentials));
                        }
                        else
                        {
                            Log("Loading server credentials failed with error. Error: " + error);
                        }
                    });
}

private IEnumerator VerifyIosServerCredentials(ServerCredentials credentials, bool isAppleArcadeGame = false)
        {
            #pragma warning disable
            WWWForm form = new WWWForm();
            form.AddField("publicKeyUrl", credentials.IosProperties.PublicKeyUrl);
            form.AddField("timestamp", System.Convert.ToString(credentials.IosProperties.Timestamp));
            form.AddField("signature", System.Convert.ToBase64String(credentials.IosProperties.Signature));
            form.AddField("salt", System.Convert.ToBase64String(credentials.IosProperties.Salt));
            form.AddField("playerId", isAppleArcadeGame ? GameServices.LocalPlayer.DeveloperScopeId : GameServices.LocalPlayer.Identifier); //Ref: https://developer.apple.com/documentation/gamekit/gklocalplayer/fetchitems(foridentityverificationsignature:)#Discussion
            form.AddField("bundleId", Application.identifier);

            UnityEngine.Networking.UnityWebRequest www = UnityEngine.Networking.UnityWebRequest.Post("https://.../authenticate", form);
            yield return www.SendWebRequest();

            if (www.result == UnityWebRequest.Result.ConnectionError || www.result == UnityWebRequest.Result.ProtocolError)
            {
                Debug.Log(www.error);
            }
            else
            {
                Debug.Log("Success response from server! " + www.downloadHandler.text);
            }
            #pragma warning restore
        }

index.ts

// Firebase function
import * as functions from 'firebase-functions';
import * as verifier from 'gamecenter-identity-verifier';

export const authenticate = functions.https.onRequest((request : any, response : any) => {

  const identity = {
    publicKeyUrl: request.body.publicKeyUrl,
    timestamp: request.body.timestamp,
    signature: request.body.signature,
    salt: request.body.salt,
    playerId: request.body.playerId,
    bundleId: request.body.bundleId
  };

  console.log("Identity : ", identity);

  verifier.verify(identity, function (err : any, token : any) {
    if (!err) {
      // use token in here.
      return response.status(200).json({ message : 'successfully verified with details : '+ (JSON.stringify(token)) });
    } else {
      console.error("Error : " , err);
      return response.status(500).json({ error :  err } );
    }
  });
 });