(AutoIt) Streaming Encryption

Encrypt and decrypt using a stream.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

; This example assumes the Chilkat API to have been previously unlocked.
; See Global Unlock Sample for sample code.

$oCrypt = ObjCreate("Chilkat.Crypt2")

; Setup encryption using the chacha20 algorithm...
$oCrypt.CryptAlgorithm = "chacha20"
$oCrypt.KeyLength = 256
$oCrypt.EncodingMode = "hex"
Local $sIvHex = "000000000000000000000002"
$oCrypt.SetEncodedIV $sIvHex,"hex"
$oCrypt.InitialCount = 42
Local $sKeyHex = "1c9240a5eb55d38af333888604f6b5f0473917c1402b80099dca5cbc207075c0"
$oCrypt.SetEncodedKey $sKeyHex,"hex"

Local $sPlainText = "The quick brown fox jumped over the lazy dog." & @CRLF

$oStream = ObjCreate("Chilkat.Stream")

; We'll save the encrypted output in eStrings to demonstrate streaming decryption next.
$oEStrings = ObjCreate("Chilkat.StringArray")

; Start a background task that will encrypt a stream.
Local $oTask = $oCrypt.EncryptStreamAsync($oStream)
Local $bSuccess = $oTask.Run()

; Write plainText to the stream, and read chacha20 encrypted text..
Local $sCipherText
Local $i
For $i = 1 To 10
    ; Note: An encryption algorithm's block size will cause buffering,
    ; and therefore not every loop iteration will produce output.
    $bSuccess = $oStream.WriteString($sPlainText)
    If ($oStream.DataAvailable = True) Then
        $sCipherText = $oStream.ReadBytesENC("hex")
        ConsoleWrite($sCipherText & @CRLF)
        $bSuccess = $oEStrings.Append($sCipherText)
    EndIf

Next

; Tell the background task that the stream has ended.
$bSuccess = $oStream.WriteClose()

; Let's make sure the background task finished.
; It should already be the case that the task is finished.
While ($oTask.Finished <> True)
    $oTask.SleepMs 20
Wend

; Get any remaining data available from the stream.
If ($oStream.DataAvailable = True) Then
    $sCipherText = $oStream.ReadBytesENC("hex")
    ConsoleWrite($sCipherText & @CRLF)
    $bSuccess = $oEStrings.Append($sCipherText)
EndIf

If ($oTask.TaskSuccess <> True) Then
    ConsoleWrite("async encryption failed:" & @CRLF)
    ConsoleWrite($oTask.ResultErrorText & @CRLF)
    $bSuccess = False
EndIf

ConsoleWrite("-- encrypt finished --" & @CRLF)

; Now decrypt to return the original.

; Reset the stream object so it can be used again.
$oStream.Reset 

; Start a background task that will decrypt a stream.
$oTask = $oCrypt.DecryptStreamAsync($oStream)
$bSuccess = $oTask.Run()

Local $iN = $oEStrings.Count
For $i = 0 To $iN - 1
    $bSuccess = $oStream.WriteBytesENC($oEStrings.GetString($i),"hex")
    If ($oStream.DataAvailable = True) Then
        $sPlainText = $oStream.ReadString()
        ConsoleWrite($sPlainText & @CRLF)
    EndIf

Next

; Tell the background task that the stream has ended.
$bSuccess = $oStream.WriteClose()

; Let's make sure the background task finished.
; It should already be the case that the task is finished.
While ($oTask.Finished <> True)
    $oTask.SleepMs 20
Wend

; Get any remaining data available from the stream.
If ($oStream.DataAvailable = True) Then
    $sPlainText = $oStream.ReadString()
    ConsoleWrite($sPlainText & @CRLF)
EndIf

If ($oTask.TaskSuccess <> True) Then
    ConsoleWrite("async decryption failed:" & @CRLF)
    ConsoleWrite($oTask.ResultErrorText & @CRLF)
    $bSuccess = False
EndIf

ConsoleWrite("-- decrypt finished --" & @CRLF)