connecting STM32 BL475E IoT01A to a HC 05

[Priyaa]

I want to pair the STM32 BL475E IoT01A to a HC05 module connected to another STM32F401ccu6 to send data to the IoT board.But when I tried to do so,I'm not able to find the pairing key anywhere.I tried 0000,1234,1111 but that didnt work.Is there any other ways to do the same