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Compress and Encrypt a Large File (Low and Constant Memory Footprint)

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Demonstrates how to compress and encrypt a large file such that the memory footprint remains low and constant.

Note: This example requires Chilkat v9.5.0.99 or greater.

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Local $bSuccess = False

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

$oCompress = ObjCreate("Chilkat.Compression")
$oCompress.Algorithm = "deflate"

; Set encryption params.
; The possible values are the same as for the corresponding properties in the Chilkat Crypt2 class/object.
; The encoded IV and Key must be specified as hex.
$oJson = ObjCreate("Chilkat.JsonObject")
$oJson.UpdateString("cryptAlgorithm","aes")
$oJson.UpdateString("cipherMode","cbc")
$oJson.UpdateInt("keyLength",128)
$oJson.UpdateInt("paddingScheme",0)
$oJson.UpdateString("encodedIV","000102030405060708090A0B0C0D0E0F")
$oJson.UpdateString("encodedKey","000102030405060708090A0B0C0D0E0F")

; Do file-to-file compression+encryption in a single call.
Local $sInPath = "qa_data/largeFile.dat"
Local $sOutPath = "c:/temp/qa_output/compressed_encrypted.dat"
$bSuccess = $oCompress.CompressEncryptFile($oJson,$sInPath,$sOutPath)
If ($bSuccess = False) Then
    ConsoleWrite($oCompress.LastErrorText & @CRLF)
    Exit
EndIf

; We can do file-to-file decrypt/decompress like this:
Local $sInPath2 = $sOutPath
Local $sOutPath2 = "c:/temp/qa_output/restored.dat"
$bSuccess = $oCompress.DecryptDecompressFile($oJson,$sInPath2,$sOutPath2)
If ($bSuccess = False) Then
    ConsoleWrite($oCompress.LastErrorText & @CRLF)
    Exit
EndIf

; Note: The above decrypt + decompress is the equivalent of doing the same in these two steps:
$oCrypt = ObjCreate("Chilkat.Crypt2")
$oCrypt.CryptAlgorithm = "aes"
$oCrypt.CipherMode = "cbc"
$oCrypt.KeyLength = 128
$oCrypt.PaddingScheme = 0
$oCrypt.SetEncodedIV "000102030405060708090A0B0C0D0E0F","hex"
$oCrypt.SetEncodedKey "000102030405060708090A0B0C0D0E0F","hex"

Local $sDecryptedPath = "c:/temp/qa_output/decrypted.dat"
$bSuccess = $oCrypt.CkDecryptFile($sInPath2,$sDecryptedPath)
If ($bSuccess = False) Then
    ConsoleWrite($oCrypt.LastErrorText & @CRLF)
    Exit
EndIf

Local $sOutPath3 = "c:/temp/qa_output/restored_in_two_steps.dat"
$bSuccess = $oCompress.DecompressFile($sDecryptedPath,$sOutPath3)
If ($bSuccess = False) Then
    ConsoleWrite($oCompress.LastErrorText & @CRLF)
    Exit
EndIf

ConsoleWrite("Success." & @CRLF)