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(Visual Basic 6.0) Streaming Compression --> Streaming Encryption
Demonstrate how to feed a compression stream into an encryption stream. This example does the following:
Data File --> Compress --> Encrypt --> Application Reads
' This requires the Chilkat API to have been previously unlocked. ' See Global Unlock Sample for sample code. Dim success As Long ' Initialize the compression object. Dim compress As New ChilkatCompression compress.Algorithm = "deflate" ' Initialize the encryption object. Dim crypt As New ChilkatCrypt2 crypt.CryptAlgorithm = "chacha20" crypt.KeyLength = 256 crypt.EncodingMode = "hex" Dim ivHex As String ivHex = "000000000000000000000002" crypt.SetEncodedIV ivHex,"hex" crypt.InitialCount = 42 Dim keyHex As String keyHex = "1c9240a5eb55d38af333888604f6b5f0473917c1402b80099dca5cbc207075c0" crypt.SetEncodedKey keyHex,"hex" ' Setup the streams. ' streamC is for compression Dim streamC As New ChilkatStream ' streamE is for encryption Dim streamE As New ChilkatStream ' The source for the compressor is a file. streamC.SourceFile = "qa_data/hamlet.xml" ' The source for the encryptor is the output of the compressor stream. success = streamE.SetSourceStream(streamC) ' Our application will be reading the output of streamE. ' Start the compression and encryption streams in background threads.. Dim taskC As ChilkatTask Set taskC = compress.CompressStreamAsync(streamC) Dim taskE As ChilkatTask Set taskE = crypt.EncryptStreamAsync(streamE) success = taskC.Run() success = taskE.Run() ' Read the compressed and encrypted bytes. Dim outData As New ChilkatBinData Do While (streamE.EndOfStream <> 1) If (streamE.DataAvailable = 1) Then success = streamE.ReadBd(outData) End If Loop ' Let's make sure the background task finished. ' It should already be the case that the task is finished. Do While ((taskE.Finished <> 1) Or (taskC.Finished <> 1)) taskE.SleepMs 20 Loop ' Get any remaining data that needs to be flushed. If (streamE.DataAvailable = 1) Then success = streamE.ReadBd(outData) End If ' Double-check for success.. If (taskE.TaskSuccess <> 1) Then Debug.Print "async encryption failed:" Debug.Print taskE.ResultErrorText success = 0 End If ' Double-check for success.. If (taskC.TaskSuccess <> 1) Then Debug.Print "async compression failed:" Debug.Print taskC.ResultErrorText success = 0 End If ' Save the compressed/encrypted data to a file. success = outData.WriteFile("qa_output/compressedEncrypted.dat") Debug.Print "The async compress/encrypt was successful." ' Let's decrypt and decompress to further verify... success = crypt.DecryptBd(outData) success = compress.DecompressBd(outData) ' outData should contain the original data.. success = outData.WriteFile("qa_output/original_hamlet.xml")
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