identity root and encryption root

[Jean-Louis Bonnaffé]

Reading the nRF51 reference manual, I came across the Identity Root and the Encryption Root fields in the FICR area.

Does anyone know what they can be used for ?

[Ulrich Myhre]

The IR and ER fields are random values used to generate some of the device information and keys used by the SoftDevice for BLE. These are not very useful for the common user, but could be used as a static identifier for a specific chip.

[Jean-Louis Bonnaffé]

Thank you, that's very clear.

[capricorn]

@Ulrich Myhre. can you tell me which is more probably unique among IR, ER, DEVICEID and DEVICEADDR. or we say whose matching probability is less in among chips released.

[Ulrich Myhre]

To my knowledge, they should all be completely random. DEVICEADDR will have two bits set according to the Bluetooth address standard. For chip identification, you generally want to use DEVICEID[0-1], but IR/ER can be used as differentiators for other things.