Why is fingerprint.com browser fingerprint working so well with iPhones? (opens in new tab)

… or …. I guess it’s possible that someone is drugging me several times a day, cloning my SIM card, putting it in another device and flying all over the U.S.

This is about precision of browser fingerprinting.

fingerprint.com generates a hash from browser/os attributes to recognize users without cookies. I tried their demo using iphone and expected (because i use private mode and returned several times with hopefully different cookie) to see some entries from other iphones like my one pop up in my history (from the fuzzy matching; https://www.apple.com/safari/docs/Safari_White_Paper_Nov_201... has some sentence about fingerprint prevention) but there were no other. I was alone and it traced me well. It was immune to private relay on/off (geodata).

They claim 99.5% accuracy for fingerprint pro. From the docs (https://dev.fingerprint.com/docs/understanding-our-995-accur...) it seems to me that 99.5% is overall accuracy for the hosted service and that number might be inflated by all the reference calls generated by devices that never clean their cookies (these count as 100%) The fraction of these is undisclosed, but its most likely very high(?).

I had, so far believed that it is more difficult to fingerprint a mobile safari than a desktop or android, because there is not so much hardware variety. Canvas/audio fingerprint should mainly depend on the phone’s model, and so are the fonts? (can apps bring new fonts to the fingerprint?)

Yet the demo of fingerprint.com performs pretty well for me. I do not know if its a problem of my safari leaking something or whether I am the only current user of the demo and therefore have no other peers to compare against. It seems a general problem also on sites like amiunique.org that almost nobody uses them. amiunique reports current iphone user agent as having a 0.4% fraction in last 15 days; but there are millions of these phones out there?

First I thought its my cookies but safari is indeed in private mode and e.g. samy.pl/evercookie test shows different digits each visit.

Anybody has some link/test tool especially crafted for iphone/ipad fingerprint or has some know-how of the “secret sauce” of fingerprint.com et al and would like to share? i would like to know how my iphone SE is different from other iphone SE. how to find out? Do you see conflicting peers on fingerprint.com demo when using it with iphone?

Thanks a lot.

Other sites seem to struggle remembering my browser too, i'm not doing anything special to my knowledge.