Account numbers are very important. Every person will receive a number of account numbers based on the financial resources/liabilities they have. They will have 1 main account. Any money sent to the person will deposit into this account. The account number is their NIN+01. Knowing this information does not grant a bad actor access to their money. Credit cards and loans will also use their NIN + 2 digits for those accounts. For example, if someone acquired a credit card, their account number might be the NIN+41. The creditor account number will be issued by KNB to assure that no two account numbers are the same. This makes it much easier to pay an account as the account holder will just need to remember the last 2 digits of the account number, and this will assume they already know their NIN.
Someone sending money to another person will just need to know the NIN. This is a deposit only number, and just by knowing the NIN does not grant access to take money out of the account. This is designed to keep bad actors from taking money out of the account just by knowing an account number. This is using the same philosophy that if you know I have $100, does not grant you access to my $100. The only way a bad actor can gain access to your money is by knowing your UID/Password combination. If the account holder setup 2FA, then knowing these two things does not help the bad actor. A 2FA code will be sent anytime a new device is trying to access the account. The best and all around solution is to acquire an KCI device, and use the K-Wallet app to hold the authenticator codes. The account owner will receive an email anytime the account was attempted through a new device. This allows the owner to change their password immediately.
This makes the banking system simply more secured than most other accounts. This is designed in such a way that being cashless does not have much friction. Sending money is easy through the KNB app which will be available for any of the major mobile OSes (Android/iOS/Kal-OS). People should be locking their phone, and use biometric to log into their KNB account. This means any device the app is installed on must have biometric support.