However if your identity can be verified by some respected authority, you can be issued a unique key pair that can be bound to your identity by that authority. The certification authority must verify the identity of the applicant, issue the certificate and manage the status of that certificate over its lifetime. Anyone must be able to verify the issued certificate and be able to check its current status. The basics are relatively simple and can be created by simply extending relationships in the physical world into the networked world. The banking industry is a good example of a global infrastructure which acts as a type of certifying authority.
Customers establish relationships with local banks.
The customer is given an account number which identifies them to that bank. When the customer issues instructions to pay another vendor out of an account, the bank executes that instruction. The remote bank doesn't know the customer, but they do know the bank. In a sense, the bank authenticates the customer to the foreign bank. Let's say that the account is a business account and the company which holds that account wants to buy or sell in another country.