_Crypt_EncryptData slow stream of data

[jvds]

i'm working on a simple chat client so i can chat direcly ip <--> ip but i want to log my chats and encrypt them, I don't want to create a log and encrypt every msg separately (creating a patern in the logs)

i was trying to understand the _Crypt_EncryptData func with the false flag but fail to understand it, here is encryption test
 

$vCryptKey = "CryptPassword"
$iAlgID = $CALG_AES_128

 _Crypt_Startup()
$vCryptKey = _Crypt_DeriveKey($vCryptKey, $iAlgID)
$EncryptData = ""
for $x=1 to 3
    $data = random(100,999,1)&"-" ;some random data to simulate a stream of data
    $EncryptData &= _Crypt_EncryptData($data, $vCryptKey, $CALG_USERKEY, False)
    if @error then ConsoleWrite('@error='&@error&"  @extended"&@extended &@lf)
    Sleep(1000)
Next
ConsoleWrite('$EncryptData='&$EncryptData&@lf)

;decrypt $sOutput
$DecryptData = _Crypt_DecryptData($EncryptData, $vCryptKey, $CALG_USERKEY)
ConsoleWrite('$DecryptData='&$DecryptData&@lf)

_Crypt_DestroyKey($vCryptKey)
_Crypt_Shutdown()