Android Question advertizing id - generates set of zeros

read this:

Google Play services update in 2021​

As part of Google Play services update in late 2021, the advertising ID will be removed when a user opts out of personalization using advertising ID in Android Settings. Any attempts to access the identifier will receive a string of zeros instead of the identifier. To help developers and ad/analytics service providers with regulatory compliance efforts and respect user choice, they will be able to receive notifications for opt-out preferences. If you want to test the aforementioned notification system, fill out this form.

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Andrew (Digitwell) said:

read this:

Advertising ID - Play Console Help

The advertising ID is a unique, user-resettable, and user-deletable ID for advertising, provided by Google Play services. It gives users better controls and provides developers with a simple, standard

support.google.com

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Oh, thanks
So this is also gone, so how can I identify the user/device?
I need this as I have 2 apps on the same device (each written different signature key so the device ID is different) that I need them to share data using a unique identifier?
The first app is a live one that uses device ID and i can't change it now

Thanks

Do a search of the forum for Unique ID. There are plenty of posts on the subject. Android is constantly changing the rules on this.

Andrew (Digitwell) said:

Do a search of the forum for Unique ID. There are plenty of posts on the subject. Android is constantly changing the rules on this.

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ive been searching for long - no such thing anymore
the device / android will not let you access any of the "hard" ids
if you take "device_id" in one app and then with other app - if they're not using the same signature key you'll get different device_id so this is a signature dependent element

i've solved my problem using ip address as i needed an identifier for the minute so two of my app will be able to identify they're running on the same device, i could use mac address as well

i've been searching this for many months - no id i could finf was someting to rely on in multi apps and multi signatures environment