The Republic of Estonia uses such a system to identify members of its e-Residency program, even with no physical presence. Each e-resident has a public numerical key that serves as a unique identifier, and a corresponding private key that is never revealed.
So an example to emulate then!
Except: Estonia suffered an embarrassing blow to its much-vaunted ID cards that underpin everything from electronic voting to online banking [...] a security risk that affects almost 750,000 ID cards and that would enable a hacker to steal a person’s identity.
https://www.ft.com/content/874359dc-925b-11e7-a9e6-11d2f0ebb...