2.4.2.4 Crypto_Aead_AesEax_Final

crypto_Aead_Status_E Crypto_Aead_AesEax_Final(
    st_crypto_Aead_AesEax_Ctx *ptr_aesEaxCtx_st, 
    uint8_t *ptr_authTag, 
    uint32_t authTagLen
    );

Description

This API is used to obtain the authentication tag for AES-EAX encryption. To use it, first initialize the context by calling the Crypto_Aead_AesEax_Init function. Then, calculate the authentication tag by calling Crypto_Aead_AesEax_Cipher. Finally, only after completing these steps, call this API.

Parameters


No.	Argument Type	Argument Name	Type	Description
1	st_Crypto_Aead_AesEax_ctx*	ptr_aesEaxCtx_st	Input	AES-EAX Algorithm context
2	uint8_t*	ptr_authTag	Output/Input	Pointer to store authentication tag value
3	uint8_t*	authTagLen	Input	Authentication tag length in bytes, max 16 bytes

Returns


Return Type	Description
crypto_Aead_Status_E	Function returns the status of the API.

Prerequisites

To use the HW handler, the algorithm must be enabled in Crypto v4 in MPLAB® Code Configurator.
To use the SW handler, the algorithm must be enabled in wolfCrypt, and linked to Crypto V4 in MPLAB® Code Configurator.
Crypto_Aead_AesEax_Init, Crypto_Aead_AesEax_Cipher, Crypto_Aead_AesEax_AddAadData and must be called prior to calling Crypto_Aead_AesEax_Final.

Example

#define sessionID 1
crypto_Aead_Status_E status;
crypto_HandlerType_E handlerType_en = CRYPTO_HANDLER_SW_WOLFCRYPT;
crypto_CipherOper_E cipherOper_en = CRYPTO_CIOP_ENCRYPT;
st_Crypto_Aead_AesEax_ctx AesEax_ctx ;
uint8_t inputData[32] = {/*data*/};
uint32_t dataLen = sizeof(inputData);
uint8_t key[32] = {/*data*/};
uint32_t keyLen = sizeof(key);
uint8_t outData[32];
uint8_t nonce[32] = {/*data*/};
uint32_t nonceLen = sizeof(nonce);
uint8_t authTag[32];
uint32_t authTagLen = 16; // auth tag can be 4-16
uint8_t aad[32] = {/*data*/};
uint32_t aadLen = sizeof(aad);

crypto_Aead_Status_E status;

status = Crypto_Aead_AesEax_Init(
    &AesEax_ctx, 
    handlerType_en, 
    cipherOper_en, 
    key, 
    keyLen, 
    nonce, 
    nonceLen, 
    ptr_aad, 
    aad, 
    sessionID
    );
    
status = Crypto_Aead_AesEax_Cipher(
    &AesEax_ctx, 
    inputData, 
    dataLen, 
    outData, 
    aad, 
    aadLen
    );

status = Crypto_Aead_AesEax_AddAadData(
    &AesEax_ctx, 
    aad, 
    aadLen
    );

status = Crypto_Aead_AesEax_Final(
    &AesEax_ctx, 
    authTag, 
    authTagLen
    );