This model is for the scenarios where one device has input functionality but not the display functionality and other devices have only display functionality. The user is shown a six-digit number 456654 on the device with a display and then asked to enter the number on the other device. If the number entered in the other device is correct, the connection is paired.
According to Bluetooth SIG, Just Works and Passkey Entry do not provide any passive eavesdropping protection. This is because Secure Simple Pairing uses Elliptic Curve Diffie-Hellman and LE legacy pairing does not.
