/******************************************************************************
* @fn SSP_CCM_InvAuth_Decrypt
*
* @brief Verifies CCM authentication.
*
* input parameters
* @param decrypt if set to 'true' then run decryption and set to 'flase' for
* authentication only.
* @param Mval - Length of authentication field in octets [0,2,4,6,8,10,12,14 or 16]
* @param N - Pointer to 13-byte Nonce
* @param C - Pointer to octet string 'c' = 'm' || auth tag T
* @param len_c - Length of C[] in octets
* @param A - Pointer to octet string 'a'
* @param len_a - Length of A[] in octets
* @param AesKey - Pointer to AES Key or Pointer to Key Expansion buffer.
* @param Cstate - Pointer to AES state buffer (cannot be part of C[])
* @param ccmLVal - ccm L Value to be used.
*
* output parameters
*
* @param Cstate[] - The first Mval bytes contain computed Authentication Tag T
*
* @return 0 = Success, 1 = Failure
*
*/
uint8 SSP_CCM_InvAuth_Decrypt (bool decrypt, uint8 Mval, uint8 *N, uint8 *C, uint16 len_c, uint8 *A,
uint16 len_a, uint8 *AesKey, uint8 *Cstate, uint8 ccmLVal)
{
unsigned char status;
if((status = CCMInvAuthDecryptStart(decrypt, Mval, N, C, len_c, A, len_a, 0, Cstate,
ccmLVal, false))!= AES_SUCCESS )
{
return status;
}
/* wait for completion of the operation */
do
{
ASM_NOP;
}while(!(CCMInvAuthDecryptCheckResult()));
if((status = CCMInvAuthDecryptGetResult(Mval, C, len_c, Cstate)) != AES_SUCCESS)
{
return status;
}
return AES_SUCCESS;
}
//*****************************************************************************
//
// brief AES-CCM decrypt example
//
// param bDecrypt if set to true run decryption
// param pui8Key pointer to Key
// param ui8Mval length of authentication
// param pui8N Nonce
// param C input encrypted message
// param ui16LenC length of message
// param pui8A Additional data
// param ui16LenA length of additional data
// param ui8KeyLocation location in Key RAM. Must be one of
// the following:
// KEY_AREA_0
// KEY_AREA_1
// KEY_AREA_2
// KEY_AREA_3
// KEY_AREA_4
// KEY_AREA_5
// KEY_AREA_6
// KEY_AREA_7
// param ui8CCMLVal Lval for ccm
// param ui8CCMIntEnable set to true to enable interrupts and false to
// disable
// param pui8ExpectedOutput pointer to expected output
// param pui8Cstate authentication Tag
// param ui8CCMIntEnable set true/false to enable/disable interrupts
// param pui8ExpectedOutput pointer to Expected Output
//
//return AES_SUCCESS if successful
//
//*****************************************************************************
uint8_t CCMDecryptExamples(bool bDecrypt,
uint8_t* pui8Key,
uint8_t ui8Mval,
uint8_t *pui8N,
uint8_t *pui8C,
uint16_t ui16LenC,
uint8_t *pui8A,
uint16_t ui16LenA,
uint8_t ui8KeyLocation,
uint8_t *pui8Cstate,
uint8_t ui8CCMLVal,
uint8_t ui8CCMIntEnable,
uint8_t *pui8ExpectedOutput)
{
uint8_t status;
if(ui8CCMIntEnable)
{
//
// example using interrupt service routine
//
if((status = AESLoadKey((uint8_t*)pui8Key, ui8KeyLocation)) !=
AES_SUCCESS)
{
return status;
}
if((status = CCMInvAuthDecryptStart(bDecrypt, ui8Mval, pui8N, pui8C,
ui16LenC, pui8A, ui16LenA,
ui8KeyLocation, pui8Cstate,
ui8CCMLVal, ui8CCMIntEnable)) !=
AES_SUCCESS)
{
return status;
}
//
// wait for completion of the operation
//
do
{
ASM_NOP;
}while(ui8CCMIntHandler == 0);
ui8CCMIntHandler = 0;
if((status = CCMInvAuthDecryptGetResult(ui8Mval, pui8C, ui16LenC,
pui8Cstate)) != AES_SUCCESS)
{
return status;
}
}
else
{
//
// example using polling
//
if((status = AESLoadKey((uint8_t*)pui8Key,
ui8KeyLocation)) != AES_SUCCESS)
{
return status;
}
if((status = CCMInvAuthDecryptStart(bDecrypt, ui8Mval, pui8N, pui8C,
ui16LenC, pui8A, ui16LenA,
ui8KeyLocation, pui8Cstate,
ui8CCMLVal,
ui8CCMIntEnable))!= AES_SUCCESS )
{
return status;
}
//
// wait for completion of the operation
//
do
{
ASM_NOP;
}while(!(CCMInvAuthDecryptCheckResult()));
if((status = CCMInvAuthDecryptGetResult(ui8Mval, pui8C, ui16LenC,
pui8Cstate)) != AES_SUCCESS)
{
return status;
}
}
//
// Verify CCM output
//
if (CCMMemCmp(pui8C, (uint8_t const *)pui8ExpectedOutput,
(ui16LenC-ui8Mval)) == false)
{
return AES_CCM_TEST_ERROR;
}
return AES_SUCCESS;
}