Immutable Device IDs

In Android 6 and higher, Wi-Fi service providers and packet analyzers have been restricted from retrieving a device’s factory MAC address through the Wi-Fi stack from network requests. Starting in Android 10, additional restrictions are in place that limit access to device identifiers (IDs) to apps with the privileged permission level. This protects device IDs such as

  • telephony IMEI, MEID, ESN, and IMSI numbers.
  • build, SIM, or USB serial numbers.

Who can access device IDs

Device IDs are restricted on all Android 10 devices, even if apps target Android 9 or lower. Device IDs can be accessed by

Privileged packages access

A package must be privileged to access device IDs. It must have READ_PRIVILEGED_PHONE_STATE permission in the Manifest.permission class, and be whitelisted in the privapp-permission.xml file. For information on the whitelist process, see Privileged Permission Whitelisting.

For information on getting a unique ID for a nonprivileged package, refer to Common use cases and the appropriate identifier to use.

Restricted device IDs and randomized MAC addresses

To further restrict device IDs, all devices on Android 10 transmit randomized MAC addresses by default for both probe and associated requests, and must have a different randomized MAC address for each SSID. Don’t use the device factory MAC address in client mode, soft access point (AP), or Wi-Fi Direct use cases. It must remain hidden from publicly accessible APIs that aren’t privileged apps. Privileged apps that require the factory MAC address to be returned are required to have LOCAL_MAC_ADDRESS permission.

Users have the option to keep the default randomized MAC address that's assigned to each SSID. The option is viewable under Privacy in Settings > Network details. To learn about obtaining a randomized MAC address see Randomized MAC addresses.

Screen shows if device ID uses a randomized MAC address for privacy
Figure 1.MAC address shows as randomized under Privacy in Network details

Apps that invoke device ID APIs

Apps that invoke device ID APIs must meet the Android 10 requirements. Otherwise, when they try to access device IDs the following is returned:

  • Apps targeting Android 10
  • Apps targeting Android 9 or earlier
    • If they have the READ_PHONE_STATE permission, either a null response or placeholder data is returned.
    • If they don’t, the device ID APIs throw a SecurityException that contains the name of the method called, and an indication that the calling app doesn’t meet the requirements to access the requested ID.

For more on immutable device IDs see Nonresettable device identifiers and best practices for unique identifiers.

Testing

Apps must be prevented from accessing the device serial number and, where applicable, IMEI / MEID, SIM serial number, and subscriber ID. Apps with permission to access these IDs must also meet one of the criteria listed under Who can access device IDs.