Devices, systems and methods are provided to implement key generation for secure pairing between first and second devices using embedded out-of-band (OOB) key generation and without requiring the devices to have input/output (IO) capability to enter authentication information. Bluetooth Smart or Low Energy (BLE) OOB pairing option can be used for pairing medical devices with added security of OOB key generation. The OOB key generation comprises providing first and second devices with the same predefined credential and secure hashing algorithm, and making input of the hashing algorithm of the first and second devices the same. The first device transmits unique data to second device (e.g., via BLE advertising) to share and compute a similar input. The first and second devices use the credential and shared data with the hashing function to generate a key that is the same at each of first and second devices.