[rampage101]

The problem is that SSN's are treated like a private key. If somebody has that private key, and some basic information about you, they can basically impersonate you electronically.

Meanwhile countries like Estonia use an electronic card reader with a PIN to verify digital identity, making it nearly impossible for somebody to impersonate you. Using this Estonian system, you can tell anybody your personal code ID.

[bonzini]

In Italy the personal id is computed from name(s), surname, date and place of birth (state of birth if born abroad) and a check digit. Collisions are pretty rare (one every few tens of thousands of people), so it's pretty much a public piece of information.

Electronic identification is available on three levels: id+password, id+password+OTP (the most common), id+password+smart card (everybody has one, but in practice it is only used by officers nowadays). Getting a password is free and takes about 15 minutes plus a trip to the post office. It works pretty well, and underneath it's just SAML2 so everyone can use it.