AES CCM co-processor standalone usage

[Hiihtaja]

Hello !

nRF52840 have "128-bit AES/ECB/CCM/AAR co-processor (on-the-fly packet encryption)" what is expected to be used together with RADIO for encrypt/decrypt packages on fly.

E.g PS chapter 6.4

Can it be used without RADIO ?

I need this crypto operation and would like to execute it from one memory buffer to other memory buffer. May be even have interrupt what indicate end of operation.

But polling mode is OK as well.

Does existing registers of this co-processor support standalone usage of it ?

Regards,

Eugene

[Sigurd]

I need this crypto operation and would like to execute it from one memory buffer to other memory buffer. May be even have interrupt what indicate end of operation.

You can use the ECB https://infocenter.nordicsemi.com/index.jsp?topic=%2Fps_nrf52840%2Fecb.html

If you use the SoftDevice, use the SoftDevice API. https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.s140.api.v7.3.0/group___n_r_f___s_o_c___f_u_n_c_t_i_o_n_s.html#ga79280d697e7ba03810c6473b0c7dab87

[Hiihtaja]

Hello !

I'm not using SoftDevice and I think AES-CCM coprocess can be fully controlled.

Can I use AES-128 CCM from my code for encrypt/decrypt own data  without any relation with radio ?

Usage with radio is explained in PS, but looks like no any source examples.

Looks like ECB is also interesting but it can be used for encryption and for example CC310 for decryption.

Do you have any example of source code for evaluate AES ECB ?

Regards,

Eugene

[Sigurd]

Hi,

CCM is coupled with the radio, so for a non-radio related AES operation it's better to use ECB. ECB uses the same AES core as the CCM. I'm not aware of any examples, but the HAL should be fairly straight forward to use. https://github.com/NordicSemiconductor/nrfx/blob/nrfx-1.x/master/hal/nrf_ecb.c

[Hiihtaja]

Hi  !

Looks like ECB mode supports only encryption operations.

Is this so ?

Regards,

Eugene

[Sigurd]

I believe the mode "AES Encrypt" can actually decrypt and encrypt data (it's just that you're limited to certain block cipher modes).

See this post:  devzone.nordicsemi.com/.../intro-to-application-level-security-using-the-ecb-

[Hiihtaja]

Hi !

Can it be so than AES-CCM coprocessor is always slowly than CC310  ?

It works synchronously with radio according data-rate speed DATARATE.

In this register not specified max speed mode.

Or any other value put it to async mode and we can similar result as for CC310 ? ( 3x faster for 255 frame)

May be for short frames there are equal timing.

Regards,

Eugene

[Sigurd]

Hi,

I don't have any numbers at hand, maybe you can use the crypto examples in the SDK for some benchmarking. https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/crypto_examples.html

As it seems like the original question in this case is answered, I think we can close this case.