https://devzone.nordicsemi.com/f/nordic-q-a/29142/aes-ccm-encryption-by-s132-timeslot-apiHi, I have posted the same question in the following URL. devzone.nordicsemi.com/.../ It will be very helpful if you tell me how to get a correct MIC result by AES CCM mode encryption of nRF52832. I send you my sample(blinky_ccm.zip). I&#39;m usingen-USTelligent Community 13Mon, 15 Jan 2018 10:18:25 GMThttps://devzone.nordicsemi.com/thread/115789?ContentTypeID=1Mon, 15 Jan 2018 10:18:25 GMT137ad170-7792-4731-bb38-c0d22fbe4515:7fb61b3a-c7ce-497a-898b-7d5d616f54f0run_ar<p>What are you actually trying to do here? Calling ccm_crypt_pair_request_prepare doesn&#39;t actually do anything, it only generates the pair_request_packet. This needs to be sent to the peer and applied there using the ccm_crypt_pair_request_accept function. Then you can use ccm_crypt_packet_encrypt to encrypt the packet, send it to the peer that can use ccm_crypt_packet_decrypt to un encrypt the packet.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/115788?ContentTypeID=1Thu, 28 Dec 2017 04:36:12 GMT137ad170-7792-4731-bb38-c0d22fbe4515:b9effc89-256e-40c5-a00f-c4331193521cALE<p>Thank you for your comment. I have tried to call ccm_crypt_pair_request_prepare() for only one time after the first timeout. But it doesn`t work. We still cannot obtain the expected MIC . I have also tried to call ccm_crypt_pair_request_prepare() for only one time in the main(). And the MIC is also wrong. Could you provide a sample so that I can get the expected MIC?</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/115787?ContentTypeID=1Wed, 20 Dec 2017 13:58:32 GMT137ad170-7792-4731-bb38-c0d22fbe4515:3ce9f09b-754f-48e1-a967-278a83d90556run_ar<p>As far as I can see you call ccm_crypt_pair_request_prepare every time the timer fires. Could you try to call this only once?</p><div style="clear:both;"></div>