AES-128 encryption problem（Tom’s）

[helen]

Hi

      1、The customer wants to use  AES-128 encryption in their project and want to know how much flash and RAM space does  AES-128 encryption use ，I found cifra_AES128-EAX folder in directory nRF5_SDK_17.0.2_d674dde\external\cifra_AES128-EAX of sdk，But I see that the project in the directory nRF5_SDK_17.0.2_d674dde\examples\ble_peripheral don't use the files in the directory nRF5_SDK_17.0.2_d674dde\external\cifra_AES128-EAX.

     2、I found the aec files as figure below in the ble_app_hrs project,but  these aec files are not in the directory nRF5_SDK_17.0.2_d674dde\external\cifra_AES128-EAX，I don‘t know whether this project  use AES-128 encryption；

[Einar Thorsrud]

Hi,

The ble_app_hrs does not use AES.128-AEX. I am not entirely sure which variant of AES-128 the customer wants to use? Do you know it is AEX? There are several variants, so that is key information. The flash and RAM consumption depends on the algorithm, and which library is used.

the nRF5 SDK includes the nrf_crypto library, which is a frontend for many different crypto libraries and is used across the nRF5 SDK wherever crypto is needed. It is not a requirement to use that, but I suggest looking at that first. The documentation there is quite good, and there are a number of examples in the SDK (<SDK>\examples\crypto\nrf_crypto\).