like boxes, which 
 get more precise based on the number 
 of letters and digits. Exclusive IP addresses The Relay IP addresses used by Private Relay are no...

https://www.apple.com/jp/privacy/docs/iCloud_Private_Relay_Overview_Dec2021.PDF

Developers can call a local refresh API (getCredentialsState) to confirm that the user is still securely signed in to iCloud on the device and allow the use...

https://www.apple.com/jp/privacy/docs/Sign_in_with_Apple_White_Paper_Nov_2019.pdf