Can I change the Crypto backend of BLE controller in SoftDevice?

[Deeper]

I want to use mbed TLS backend in BLE stack.

For example, BLE controller will use AES(hardware accelerator, I think) to gennerate link key and encrypt.

I know that SoftDevice is not opensource, so I want to know if it's possible to change the Crypto backend  to software implementation like mbed TLS ?

[Vidar Berg]

The CCM (CCM — AES CCM mode encryption) peripheral provides on the fly encryption/decryption of data transmitted or received by the RADIO, so it's purely HW. Although you could use Mbed TLS for the key exchange during LESC pairing.