The NIN is public for a number of reasons. This is designed to provide for an ID number without any consequences for someone to know it. The more significant number is the GIN which will intend to be between the number holder and government only. The NIN is the bank account number. This allows someone to transfer money from their bank account to another bank account with just by knowing the number. This is also the baseline for the telephone. It is also used as a private address with the postal system. And since this is a national ID number, this is also the number to be on ID cards, and therefore something the person can learn quickly, and easily.