static int32_t hmacIntermediate()

in source/sigv4.c [2405:2452]
35 lines of code
4 McCabe index (conditional complexity)

static int32_t hmacIntermediate( HmacContext_t * pHmacContext,
                                 const char * pData,
                                 size_t dataLen )
{
    int32_t returnStatus = 0;
    size_t i = 0U;
    const SigV4CryptoInterface_t * pCryptoInterface;

    assert( pHmacContext != NULL );
    assert( dataLen > 0U );
    assert( pHmacContext->key != NULL );
    assert( pHmacContext->pCryptoInterface != NULL );
    assert( pHmacContext->pCryptoInterface->hashInit != NULL );
    assert( pHmacContext->pCryptoInterface->hashUpdate != NULL );
    assert( pHmacContext->pCryptoInterface->hashFinal != NULL );
    assert( pHmacContext->keyLen == pHmacContext->pCryptoInterface->hashBlockLen );

    pCryptoInterface = pHmacContext->pCryptoInterface;

    /* Derive the inner HMAC key by XORing the key with inner pad byte. */
    for( i = 0U; i < pCryptoInterface->hashBlockLen; i++ )
    {
        /* XOR the key with the ipad. */
        pHmacContext->key[ i ] ^= HMAC_INNER_PAD_BYTE;
    }

    /* Initialize the Hash Crypto interface for performing new hash operation
     * of H(Inner Key || Data) in the HMAC algorithm. */
    returnStatus = pCryptoInterface->hashInit( pCryptoInterface->pHashContext );

    if( returnStatus == 0 )
    {
        /* Hash the inner-padded block-sized key. */
        returnStatus = pCryptoInterface->hashUpdate( pCryptoInterface->pHashContext,
                                                     pHmacContext->key,
                                                     pCryptoInterface->hashBlockLen );
    }

    if( returnStatus == 0 )
    {
        /* Hash the data. */
        returnStatus = pCryptoInterface->hashUpdate( pCryptoInterface->pHashContext,
                                                     ( const uint8_t * ) pData,
                                                     dataLen );
    }

    return returnStatus;
}