.NET Core 2.1 Apple Push Notifications

I have to send push notifications to specific iOS devices with my .Net Core WebAPI that will be executed on a Windows 2008 Server R2. The server itself should not be the problem because it is working with a node.js library. But I want it to work with an WepAPI in ASP .Net Core 2.1 which is self hosted with the inbuilt Kestrel Server. Maybe you've got an idea how to solve this problem.

My Code:

// This will encode the jason web token apns needs for the authorization
// get the base64 private key of the .p8 file from apple
string p8File = System.IO.File.ReadAllText(Settings.Apn.PrivateKey);
p8File = p8File.Replace("-----BEGIN PRIVATE KEY-----", string.Empty);
p8File = p8File.Replace("-----END PRIVATE KEY-----", string.Empty);
p8File = p8File.Replace(" ", string.Empty);

byte[] keyData = Convert.FromBase64String(p8File);
ECDsa key = new ECDsaCng(CngKey.Import(keyData, CngKeyBlobFormat.Pkcs8PrivateBlob));

ECDsaSecurityKey securityKey = new ECDsaSecurityKey(key) { KeyId = Settings.Apn.KeyId };
SigningCredentials credentials = new SigningCredentials(securityKey, "ES256");

SecurityTokenDescriptor descriptor =
    new SecurityTokenDescriptor
        {
            IssuedAt = DateTime.Now,
            Issuer = Settings.Apn.TeamId,
            SigningCredentials = credentials
        };

JwtSecurityTokenHandler jwtHandler = new JwtSecurityTokenHandler();
string encodedToken = jwtHandler.CreateEncodedJwt(descriptor);
this.log?.LogInformation($"Created JWT: {encodedToken}");

// The hostname is: https://api.development.push.apple.com:443
HttpClient client = new HttpClient { BaseAddress = new Uri(Settings.Apn.Hostname) };
client.DefaultRequestHeaders.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
this.log?.LogInformation("Initialized new HttpClient.");

// payload content for the apns
JObject payloadData = new JObject
                          {
                              new JProperty("alert", data.Message),
                              new JProperty("badge", 2),
                              new JProperty("sound", "default")
                          };
JObject payload = new JObject
                       {
                           new JProperty("aps", payloadData)
                       };
this.log?.LogInformation($"Setup payload: {payload}");

// HttpRequestMessage that should be send
HttpRequestMessage request = new HttpRequestMessage(
                                 HttpMethod.Post,
                                 $"{Settings.Apn.Hostname}/3/device/{data.DeviceId}")
                                 {
                                     Content = new StringContent(JsonConvert.SerializeObject(payload), Encoding.UTF8, "application/json")
                                 };
this.log?.LogInformation("Setup HttpRequestMessage.");

// Setup the header
request.Headers.Add("Authorization", $"Bearer {encodedToken}");
request.Headers.Add("apns-id", Guid.NewGuid().ToString());
request.Headers.Add("apns-expiration", DateTime.Now.AddDays(1).ToString(CultureInfo.InvariantCulture));
request.Headers.Add("apns-priority", "10");
request.Headers.Add("apns-topic", "de.gefasoft-engineering.FabChat");

// Debug logging
this.log.LogDebug(request.ToString());
this.log.LogDebug(await request.Content.ReadAsStringAsync());
this.log.LogDebug(request.RequestUri.Host + request.RequestUri.Port);

// Send request
var result = await client.SendAsync(request);
this.log?.LogInformation("Sent request.");
this.log?.LogInformation(await result.Content.ReadAsStringAsync());

I always get following Exception thrown:

System.Net.Http.HttpRequestException: The SSL connection could not be established, see inner exception. ---> System.Security.Authentication.AuthenticationException: Authentication failed, see inner exception. ---> System.ComponentModel.Win32Exception: The message received was unexpected or badly formatted --- End of inner exception stack trace ---

Use CorePush lib

It's very lightweight. I use it across all my projects to send Firebase Android/WebPush and Apple iOS push notifications. Useful links:

1. NuGet package
2. Documentation

The interface is very simple and minimalistic:

Send APN message:

var apn = new ApnSender(settings, httpClient);
await apn.SendAsync(notification, deviceToken);

It can also send Android FCM message if needed:

var fcm = new FcmSender(settings, httpClient);
await fcm.SendAsync(deviceToken, notification);