This post is written by Yashlin Naidoo, Cloud Support Engineer.

Amazon Simple Notification Service (Amazon SNS) enables you to send notifications directly to a mobile push endpoint. For iOS apps, Amazon SNS dispatches the notification on your application’s behalf to the Apple Push Notification service (APNs).

To send mobile push notifications via Amazon SNS, you must provide a set of credentials to connect to the APNs (see Prerequisites for Amazon SNS user notifications).

Amazon SNS supports two methods for authenticating with iOS mobile push endpoints when sending a mobile push notification via the APNs:

  • Certificate-based authentication
  • Token-based authentication

To use certificate-based authentication, you must configure Amazon SNS with a provider certificate. Amazon SNS will use this certificate on your behalf to establish a secure connection with the APNs to dispatch your mobile push notifications. For each application that you support, you will need to provide unique certificates.

As the number of applications you manage grows, you will also need to create and manage an increasing number of certificates. Furthermore, certificates expire yearly, and you must renew them to ensure that Amazon SNS can continue to send mobile push notifications on your behalf. To learn more about how to use certificate-based authentication, see Certificate-based authentication for iOS applications with Amazon SNS on the AWS Compute Blog.

For new and existing iOS applications, we recommend that you use token-based authentication. To learn more about how to use token-based authentication, see Token-Based authentication for iOS applications with Amazon SNS on the AWS Compute Blog.

There are several benefits in using token-based authentication:

  • You can use a single token that is shared among all of your applications.
  • You can remove the need for yearly certificate renewal for certificate-based authentication.
  • You can improve the security of your application by using token-based requests. For these requests, your credentials are never transferred from Amazon SNS to your mobile push notification provider, making the communication less likely to be compromised.

Token-based authentication is the latest authentication method provided by the APNs that improves security for your applications, requires less management effort, and is more efficient. We recommend migrating as soon as possible to ensure the security and ease of operations of your applications.

This blog post provides step-by-step instructions for migrating your iOS application from certificate-based authentication to token-based authentication with Amazon SNS. You will learn how to create a new token using your Apple developer account. Next, you will migrate your platform application to token-based authentication. Finally, you will test your application by sending a test push notification via Amazon SNS to a device to confirm the successful migration.

Prerequisites

  • XCode IDE
  • iOS application with a valid p.12 certificate

Before proceeding with this migration, we recommend to stop sending push notifications to your applications until the migration is complete to avoid any disruptions in your message delivery workloads.

Walkthrough

You can also create a test platform application with token-based authentication to ensure that the Amazon SNS platform application is created successfully. Finally, you can create a device token and send a test push notification to it. Once confirmed that the application works correctly, you can migrate your main platform application to token-based authentication.

Creating a .p8 token to upload to Amazon SNS

  1. Log in to your Apple Developer account.
  2. Choose Certificates, Identifiers & Profiles.
  3. In the Keys section, choose the Add button (+).
  4. Under Register a New Key, for Key Name, type the token key name and tick the box for Apple Push Notifications service (APNs) for the key services.
  5. Select Continue.
  6. In the Register a New Key section, check that all values were entered correctly.
  7. Select Register to register the new token key.
  8. Download your token key. Store it in a safe location, as you can’t download the token key again.

Migrating your platform application from certificate-based authentication to token-based authentication

  1. Navigate to the Amazon SNS console. Expand the Mobile menu and choose Push Notification.
  2. Choose your platform application.
  3. Choose Edit. Under Apple credentials section choose Token:
    1. Under Token, select Choose file to upload the .p8 token key file.
    2. Provide values for signing key ID, team ID and bundle ID. These values can be found in your Apple Developer account. Ensure that your bundle ID is identical to the ID used for this application with certificate-based authentication.
  4. Event notifications – optional: refer to the following guide for enabling event notifications: Mobile app events
  5. Delivery status logging – optional: refer to the following guide for enabling delivery status logging: How do I access Amazon SNS topic delivery logs for push notifications? Find more information on these steps can in the Mobile push notifications best practices.
    Apple credential settings
  6. Choose Save changes. This changes your platform application to token-based authentication.

Testing push notification delivery to your device

In this section, you will test sending a push notification to your device using the Amazon SNS console and the AWS Command Line Interface (AWS CLI).

Amazon SNS console

  1. From the Amazon SNS console, navigate to your platform endpoint and choose Publish message.
  2. For message body, select Custom payload for each delivery protocol to send to the endpoint. This example uses a custom payload that allows you to provide additional APNs headers:
    Custom payload for each delivery model configuration
  3. Choose Publish message.
  4. The push notification is delivered to your device:
    iOS sample notification message

AWS CLI

Note: If you receive errors when running AWS CLI commands, make sure that you’re using the most recent AWS CLI version.
Run the following command. For target-arn, specify your platform application endpoint ARN:

aws sns publish \ --target-arn arn:aws:sns:us-west-2:123456789123:endpoint/APNS\_SANDBOX/computeblogdemo/ba7a35f8-c73d-364f-9edd-5c438add0533 \ --message '{"APNS\_SANDBOX": "{\"aps\":{\"alert\":\"Sample message for iOS development endpoints\"}}"}' \ --message-attributes '{"AWS.SNS.MOBILE.APNS.PUSH\_TYPE":{"DataType":"String","StringValue":"alert"}}' \ --message-structure json
  1. An output containing a MessageId is shown in case of successful delivery: 
    { "MessageId": "83ecb3a1-c728-5b7c-96e5-e8417d5cd4f4"}
  2. The push notification is delivered to your device:
    iOS sample notification message

Troubleshooting

You might encounter various errors when migrating to token-based authentication. This section explains how to troubleshoot these errors.

If a message is not delivered after publishing it to your platform application endpoint, refer to the Amazon CloudWatch failed logs of your platform application. These logs are named sns/your-aws-region/your-accountID/app/platform\_name/application\_name/Failure.

Once you have navigated to your platform application’s CloudWatch failed log group, click on one of the log streams based on the time that you published the message. Focus on the following attributes:

  • statusCode: error messages are grouped according to the status code.
  • status : shows whether a message was delivered successfully to the provider or if it failed to deliver.
  • providerResponse: provides the response message from the provider and is only shown in case a message failed to deliver.

We will look through messages that failed to deliver because of the following errors:

InvalidProviderToken

"providerResponse": "{\"reason\":\"InvalidProviderToken\"}","statusCode": 403,"status": "FAILURE"

The cause of this error can be an incorrect token key ID, team ID or if the token is invalid.

To resolve this issue, go to your Apple Developer account and ensure that you are providing the correct token ID, team ID and that your token key exists.

TopicDisallowed

"providerResponse": "{\"reason\":\"TopicDisallowed\"}","statusCode": 400,"status": "FAILURE"

The cause of this error can be an incorrect bundle ID or a device token that was created with the wrong bundle ID.

To resolve this issue, go to your Apple Developer account and navigate to your existing certificate used when migrating to token-based authentication. Confirm the bundle ID assigned to this certificate and ensure you are using the same ID for your platform application and also for your device tokens.

Conclusion

Developers can send mobile push notifications for the APNs using token-based authentication by using a .p8 key to authenticate an Apple device endpoint. This is the recommended authentication method due to improved security and lower management effort by removing the need for annual certificate renewal and by being able to share tokens among multiple applications.

To learn more about APNs token-based authentication with Amazon SNS, visit the Amazon SNS Developer Guide.

For more serverless learning resources, visit Serverless Land.

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