What is the GAC Services application, how does it work?

According to the introduction of Oleg Gryb, GAC Services is a Tools app on the Android platform. There is currently a 3.4.3 version released on Mar 24, 2018, you can see the details below.

This is an alternative to Google Authenticator (GA) that is integrated well with Samsung's Gear Google Authenticator Client (GAC). It has rich backup/restore capabilities, including local phone storage and Google Drive. The latter is very handy for syncing GA accounts on multiple Android devices.

The application can be started locally on Android or remotely from a Gear device. To start it from your Gear device, select "Connect to Phone" menu in GAC application. After the Gear device is connected, many options are available for transferring data between devices. A new account can be created by scanning a QR bar code or by entering a secret manually.

After the QR code scanned or entered manually, you can either send it to Gear by tapping "Send to Gear" button or save it on your phone using "Save" button.

If "Overwrite" checkbox is checked, an existing account will be updated with a new secret or a new one will be created if an account with the same name didn't exist.

Gear's GAC application should be in a waiting state to be able to receive any messages from the phone. It means that all communications with the phone are possible only after tapping "Connect to Phone" menu item in your Gear GAC app and while a connection dialog is open.

To see all accounts saved on your phone tap account list button located in a upper right corner of GAC Scanner screen.

Tapping on an individual account in the list view will open a zoomed view for a single account. A token in the zoomed view will be updated automatically when an old token is expired.

Accounts can be saved to and restored from an unencrypted or encrypted backup file stored on a local phone's storage or on Google Drive. Encryption is based on a password provided by a user. Encrypted backup will be signed with an HMAC signature to make sure that a backup is not corrupted during a restore operation.