Apple iphone authentification

Solution (Unity) + Asset: "iOS SDK Pro - Native API Access"

 public class GameCenterAuths
     {
         public string PlayerId { get; set; }
         public string BundleId { get; set; }
         public string Name { get; set; }
         public string PublicKeyUrl { get; set; }
         public string Signature { get; set; }
         public string Salt { get; set; }
         public ulong Timestamp { get; set; }
 
         public byte[] ConcatSignature()
         {
             var data = new List<byte>();
             data.AddRange(Encoding.UTF8.GetBytes(PlayerId));
             data.AddRange(Encoding.UTF8.GetBytes(BundleId));
             data.AddRange(CalcHelper.ToBigEndian(Timestamp));
             data.AddRange(Convert.FromBase64String(Salt));
             return data.ToArray();
         }
     }

Client:

 GameKitXT.LocalPlayerAuthenticated += HandleAppleLocalPlayerAuthenticated;
 GameKitXT.LocalPlayerAuthenticationFailed += HandleAppleLocalPlayerAuthenticationFailed;
 GameKitXT.AuthenticateLocalPlayer();
 
 private void HandleAppleLocalPlayerAuthenticationFailed(object sender, U3DXT.Core.U3DXTErrorEventArgs e)
     {
         SharedLib.Log.Logger.Instance.Debug("(social) not authentificated " + e.description);
     }
 
     private void HandleAppleLocalPlayerAuthenticated(object sender, EventArgs e)
     {
         SharedLib.Log.Logger.Instance.Debug("(social) authentificated");
         Game.IsAuthenfificatedByAppleService = true;
         isAuth = true;
     }
 
 /// <summary>
     /// Получить временный код подтверждения
     /// </summary>
     /// <param name="callback">(Android: code, token) (IPhone: signatire, salt)</param>
     public static void GetServerAuthCode(Action<GameCenterAuths> callback)
     {
         if (isAuth)
         {
             GameKitXT.localPlayer.gkLocalPlayer.GenerateIdentityVerificationSignature((_publicKeyUrl, _signature, _salt, _creationDateSpan, _nserror) =>
             {
                 SharedLib.Log.Logger.Instance.Debug("(social) on verif code");
                 if (_nserror != null)
                     SharedLib.Log.Logger.Instance.Debug("(social) error?" + _nserror.ToString());
 
                 SharedLib.Log.Logger.Instance.Debug("(social) _publicKeyUrl:" + _publicKeyUrl.ToString());
                 SharedLib.Log.Logger.Instance.Debug("(social) _signature:" + _signature.ToString());
                 SharedLib.Log.Logger.Instance.Debug("(social) _salt:" + _salt.ToString());
 
                 GameCenterAuths auths = new GameCenterAuths();
                 auths.BundleId = Application.bundleIdentifier;
                 auths.Name = GameKitXT.localPlayer.displayName;
                 auths.PlayerId = GameKitXT.localPlayer.playerID;
                 auths.PublicKeyUrl = _publicKeyUrl.ToString();
                 auths.Salt = _salt.ToString();
                 auths.Signature = _signature.ToString();
                 auths.Timestamp = _creationDateSpan;
 
                 callback(auths);
             });
         }
     }

Server verification:

 public class AppleSertificateVerification
     {
         public static bool ValidateSignature(GameCenterAuths auth)
         {
             try
             {
                 var cert = GetCertificate(auth.PublicKeyUrl);
                 if (cert.Verify())
                 {
                     var csp = cert.PublicKey.Key as RSACryptoServiceProvider;
                     if (csp != null)
                     {
                         var sha256 = new SHA256Managed();
                         var sig = auth.ConcatSignature();
                         var hash = sha256.ComputeHash(sig);
 
                         if (csp.VerifyHash(hash, CryptoConfig.MapNameToOID("SHA256"), Convert.FromBase64String(auth.Signature)))
                         {
                             // Valid user.
                             // Do server related user management stuff.
                             return true;
                         }
                     }
                 }
                 return false;
             }
             catch
             {
                 return false;
             }
         }
 
         private static X509Certificate2 GetCertificate(string url)
         {
             var client = new WebClient();
             var rawData = client.DownloadData(url);
             return new X509Certificate2(rawData);
         }
     }