Unfortunately, constancy is irrelevant. If a malicious app is using this API to locate you, it can detect when your wallpaper changes and use its app_id (unchanged) plus wallpaper fingerprint (changed) to phone home with "Yo, this user's wallpaper thumprint is now Y."

Android dev here. Still have the same default wallpaper as my Pixel 3 came with 3 years ago.

That wallpaper would have the same 3 colors as many, many, other people. The problem here arises when your wallpaper is unique, no?

You can still use as input along with other parts that are accessible without any permissions - for example the android version, device name, IP address...

Do they? I've had the same "live wave animation"(that looks like the PS3's XBM menu) for at least 5 years now and I don't see any reason to change it.

It's been more than a year since I last changed my wallpaper.

I've used the same wallpaper on every computing device I've owned, for the last 26 years.

With the downside of fingerprinting yourself it seems, would you be willing to share the wallpaper?

It isn't special, merely a blue/green colour with mild dithering.

It is a little like looking at the morning sky.

It's on all phones, desktops, etc. And if I were to give it to you? Well. Maybe you're the NSA, maybe I'll be pulled off the street, thrown into a chair, and in a NDA-drugged, mildly confused state, be told "look, it is your desktop, see your familiar backgroud? You should enter your password."

No sir, I will not disclose my background image!! Sneaky! Good try though.

I mean, I go and set up ASCIIQuarium on every phone I have. Hunting down the APK gets harder and harder though.

I don't think an average person changes wallpapers frequently.