Functions and power consumption of the Cryptographic module on nRF52840

[William Geng]

Hello I am quite new to the hardware encryption topic and I have the following questions.

On a device where the MCU samples a sensor data and stores it to a external IC at a fixed frequency

If we want the data stored on the IC to be encrypted. Is there a preferred stage where the encryption should happen in terms of reducing power consumption? i.e. realtime vs end of session

then later on we want to send the encrypted data to a mobile device through Bluetooth, what would be a secure way to share the key used for the encryption in the cryptographic module?

Many thanks in advance!

William

[Vidar Berg]

Hi William,

I don't imagine it's going to make much difference to the average current consumption if you encrypt the data on the fly or if you to it at the end. Maybe you will get a little less CPU overhead if you do it all at once. Crypto operations aren't that costly, especially when there's HW support available such as the cc310.  

I think this blog post is a good start if you want to manage encryption and key exchange in your app: 

https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/intro-to-application-level-security-using-the-ecb-

Best regards,

Vidar

[William Geng]

Many thanks! This is very helpful!