AES-CCM Tag gives wrong values

[Keerthi]

Hi,

I am working on the STM32H533RE microcontroller and implementing AES-CCM encryption using a NIST test vector for validation. While the encrypted output matches the expected result, the authentication tag generated is incorrect. I have shared the relevant code and configuration above for reference.

CRYP_HandleTypeDef hcryp;

uint32_t pKeyAES[4] = {0x40414243,0x44454647,0x48494A4B,0x4C4D4E4F};

__ALIGN_BEGIN static const uint8_t HeaderAES[16] __ALIGN_END = {

0x00, 0x08, // Length = 8 bytes

0x00, 0x01, 0x02, 0x03, // AAD

0x04, 0x05, 0x06, 0x07,

0x00, 0x00, 0x00, 0x00, // Padding

0x00, 0x00

};



__ALIGN_BEGIN static const uint32_t B0AES[4] __ALIGN_END = {

0x4f101112,0x13141516,0x00000000,0x00000004};

uint8_t sampledata[4] = {0x20, 0x21, 0x22, 0x23};
uint8_t sampleoutputdata[8];
uint32_t sampletagdata[8]; // 4 bytes


static void MX_AES_Init(void)
{

  /* USER CODE BEGIN AES_Init 0 */

  /* USER CODE END AES_Init 0 */

  /* USER CODE BEGIN AES_Init 1 */

  /* USER CODE END AES_Init 1 */
  hcryp.Instance = AES;
  hcryp.Init.DataType = CRYP_BYTE_SWAP;
  hcryp.Init.KeySize = CRYP_KEYSIZE_128B;
  hcryp.Init.pKey = (uint32_t *)pKeyAES;
  hcryp.Init.Algorithm = CRYP_AES_CCM;
  hcryp.Init.Header = (uint32_t *)HeaderAES;
  hcryp.Init.HeaderSize = 4;
  hcryp.Init.B0 = (uint32_t *)B0AES;
  hcryp.Init.DataWidthUnit = CRYP_DATAWIDTHUNIT_BYTE;
  hcryp.Init.HeaderWidthUnit = CRYP_HEADERWIDTHUNIT_BYTE;
  hcryp.Init.KeyIVConfigSkip = CRYP_KEYIVCONFIG_ALWAYS;
  hcryp.Init.KeyMode = CRYP_KEYMODE_NORMAL;
  if (HAL_CRYP_Init(&hcryp) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN AES_Init 2 */

  /* USER CODE END AES_Init 2 */

}


main()
{
 HAL_CRYP_Encrypt(&hcryp, sampledata, 4, sampleoutputdata, 1000);
      HAL_CRYPEx_AESCCM_GenerateAuthTAG(&hcryp, sampletagdata, HAL_MAX_DELAY);

}