The basic protocol from an AC charger to your car is, "hello, I have X amps available, don't take more or you will trip my circuit breaker". The car responds by

The basic protocol from an AC charger to your car is, "hello, I have X amps available, don't take more or you will trip my circuit breaker". The car responds by charging at or below the current advertised. When you charge in a context where the car unlocks the charger (i.e. Tesla Supercharger), the protocol must divulge the car's certificate, signed by the owner of the charging network (like mTLS). There would be privacy-preserving protocols for this, but they are not used in practice.