The methods below require the OneSignal SDK versions 3 & 4.It is recommended to upgrade to our latest version 5 SDKs for User Model APIs.See Update to User Model for migration steps.
OneSignal supports a higher security method known as Identity Verification. This helps prevent users from impersonating one another by generating a user-specific token on your server, if you have one. Enabling Identity Verification applies to:
  • Adding Email and SMS records into OneSignal AND associated tags.
  • Setting external_user_id for any record across all channels (Push, Email, SMS)
It can be enabled in the Dashboard > Settings > Keys & IDs Once enabled or disabled, this will take up to 10 minutes to process. We highly recommend enabling identity verification for apps and websites that use setting external_user_ids and/or Email Messaging. For apps and websites that are ‘backendless’ and do not run their own servers, we suggest either creating a minimal server that just verifies users, saving the OneSignal User ID records to your database, or avoid sending sensitive information in user tags and notifications.

​
Auth Hash Generation

Auth hashes are expected to be a HMAC on a SHA-256 of the OneSignal REST API Key and the <protected_field_value>.

​
Example Auth Hash Generation Code

When identity verification is enabled, OneSignal will look for a SHA-256 hash of a user’s email address or external user identifier from your server. See the following code examples for how to generate these hashes on your server: 
OpenSSL::HMAC.hexdigest('sha256', ONESIGNAL_API_KEY, identifier)
OpenSSL::HMAC.hexdigest('sha256', ONESIGNAL_API_KEY, email_address)

​
SDK setEmail Method

Your backend can generate an email authentication token and send it to your app to include in the setEmail method. 
var emailAddress = "[email protected]";
var emailAuthHash = "..."; // Email auth hash generated from your server
OneSignal.push(function() {
  OneSignal.setEmail(emailAddress, {
   emailAuthHash: emailAuthHash
  });
});

​
SDK setSMSNumber Method

Your backend can generate an SMS authentication token and send it to your app to include in the setSMSNumber method. 
String smsNumber = "+123456789";
String smsAuthHash = "..."; // SMS auth hash generated from your server
OneSignal.setSMSNumber(smsNumber, smsAuthHash, new OneSignal.OSSMSUpdateHandler() {
  @Override
  public void onSuccess(JSONObject result) {
    // SMS successfully synced with OneSignal
  }

  @Override
  public void onFailure(OneSignal.OSSMSUpdateError error) {
  	// Error syncing SMS, check error.getType() and error.getMessage() for details
  }
});

​
SDK setExternalUserId Method

Your backend can generate an email authentication token and send it to your app to include in the setExternalUserId method. 
let externalUserId = "123456789" // You will supply the external user id to the OneSignal SDK
let externalUserIdAuthHash = "..."; // Identifier auth hash generated from your server

OneSignal.push(function() {
  OneSignal.setExternalUserId(externalUserId, externalUserIdAuthHash);
});

​
Updating Devices with REST API

If you enabled Identity Verification and call the Add a device or Edit device endpoint (api/v1/players), the request must contain the external_user_id_auth_hash or identifier_auth_hash parameters. If you are adding or updating the external_user_id on a non-email device (device_type != 11), you must use the external_user_id_auth_hash parameter. If you are adding or updating the email (identifier parameter && device_type = 11), then any field being updated will need the identifier_auth_hash (or email_auth_hash for backwards compatibility) value.

​
Removing External User ID

To remove an external_user_id from a device record with Identity Verification enabled, you can set it to an empty string with the auth hash based on the existing external_user_id value before removal.