This exists, it's called IRMA. [0] The problem is, every data provider has to get on board first. For instance, the city you live in can verify if you're over

This exists, it's called IRMA. [0] The problem is, every data provider has to get on board first. For instance, the city you live in can verify if you're over eighteen. If their IT can handle setting the bit 'over eighteen' in the IRMA app, you can securely and verifiably show this bit of information, and only this piece of information, to the party asking to verify this information. They have to support IRMA too though. But even then, if I'm under age and just borrow your phone... [0] https://privacybydesign.foundation/en/ https://privacybydesign.foundation/en/