https://devzone.nordicsemi.com/f/nordic-q-a/62227/ecb-with-mbedtlsI am using mbedtls with ECB hard accelerator on nRF52840. So I changed the macro definition: UPDATE_CBC_MAC in ccm.c to function: #define HT_UPDATE_CBC_MAC \ for ( i = 0 ; i &lt; 16 ; i ++ ) \ y [i] ^= b [i]; \ \ if ( ( ret = ht_aes_ecb_encrypten-USTelligent Community 13Mon, 08 Jun 2020 11:35:01 GMThttps://devzone.nordicsemi.com/thread/253766?ContentTypeID=1Mon, 08 Jun 2020 11:35:01 GMT137ad170-7792-4731-bb38-c0d22fbe4515:dd763f45-036b-49e7-b7a3-2ab5bea46c3fJ&#248;rgen Holmefjord<p>Hi,</p> [quote user=""]The code runs, but I find the function: ccm_auth_crypt in ccm.c, output two result of&nbsp;<span>original function and the changed. </span>[/quote] <p>I&#39;m not sure if I understand what you mean by this. Is the input parameters not changed after the function returns? Can you give an example? Is the softdevice enabled before you call the function? Do the softdevice function call return NRF_SUCCESS?</p> <p>Best regards,<br />Jørgen&nbsp;</p><div style="clear:both;"></div>