Bluetooth Low Energy v4.0 and 4.1 used LE legacy pairing, which is similar to BR/EDR secure simple pairing and does not provide passive eavesdropping protection. The issue was later resolved in Bluetooth v4.2 and 5, which use the Diffie-Hellman Elliptic Curve algorithm for key exchange prior to pairing. The whole link is then encrypted for any further communication, avoiding any passive eavesdropping.
Bluetooth does provide a good security mechanism for paired devices, but it is still unclear how to restrict sniffers from investigating the services and characteristics of any Bluetooth Low Energy device. If you download the Nordic Connect Android/iOS application, you will be able to scan Bluetooth devices and ...
