> how would they keep it secure without resorting to one of the flawed systems I just mentioned?
It's small, hard to exploit flaws vs. large easy to exploit flaws.
> If everyone had a cryptographic private key, they would have to store it somewhere -- how would they keep it secure without resorting to one of the flawed systems I just mentioned?
Physical smartcard/smart SIM/phone. You have to steal something physical + get the PIN. Definitely possible, but really hard and if that gets lost you have to go to the Police, get yourself re-identified and get a new card. Compared what bullshit of an identifier a phone number is Estonian system is miles ahead.
It's small, hard to exploit flaws vs. large easy to exploit flaws.
> If everyone had a cryptographic private key, they would have to store it somewhere -- how would they keep it secure without resorting to one of the flawed systems I just mentioned?
Physical smartcard/smart SIM/phone. You have to steal something physical + get the PIN. Definitely possible, but really hard and if that gets lost you have to go to the Police, get yourself re-identified and get a new card. Compared what bullshit of an identifier a phone number is Estonian system is miles ahead.