(DataFlex) Streaming Encryption

Encrypt and decrypt using a stream.

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

Use ChilkatAx-9.5.0-win32.pkg

Procedure Test
    Handle hoCrypt
    String sIvHex
    String sKeyHex
    String sPlainText
    Variant vStream
    Handle hoStream
    Handle hoEStrings
    Variant vTask
    Handle hoTask
    Boolean iSuccess
    String sCipherText
    Integer i
    Integer n
    String sTemp1
    Boolean bTemp1

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

    Get Create (RefClass(cComChilkatCrypt2)) To hoCrypt
    If (Not(IsComObjectCreated(hoCrypt))) Begin
        Send CreateComObject of hoCrypt
    End

    // Setup encryption using the chacha20 algorithm...
    Set ComCryptAlgorithm Of hoCrypt To "chacha20"
    Set ComKeyLength Of hoCrypt To 256
    Set ComEncodingMode Of hoCrypt To "hex"
    Move "000000000000000000000002" To sIvHex
    Send ComSetEncodedIV To hoCrypt sIvHex "hex"
    Set ComInitialCount Of hoCrypt To 42
    Move "1c9240a5eb55d38af333888604f6b5f0473917c1402b80099dca5cbc207075c0" To sKeyHex
    Send ComSetEncodedKey To hoCrypt sKeyHex "hex"

    Move "The quick brown fox jumped over the lazy dog." + (character(13)) + (character(10)) To sPlainText

    Get Create (RefClass(cComChilkatStream)) To hoStream
    If (Not(IsComObjectCreated(hoStream))) Begin
        Send CreateComObject of hoStream
    End

    // We'll save the encrypted output in eStrings to demonstrate streaming decryption next.
    Get Create (RefClass(cComCkStringArray)) To hoEStrings
    If (Not(IsComObjectCreated(hoEStrings))) Begin
        Send CreateComObject of hoEStrings
    End

    // Start a background task that will encrypt a stream.
    Get pvComObject of hoStream to vStream
    Get ComEncryptStreamAsync Of hoCrypt vStream To vTask
    If (IsComObject(vTask)) Begin
        Get Create (RefClass(cComChilkatTask)) To hoTask
        Set pvComObject Of hoTask To vTask
    End
    Get ComRun Of hoTask To iSuccess

    // Write plainText to the stream, and read chacha20 encrypted text..

    For i From 1 To 10
        // Note: An encryption algorithm's block size will cause buffering,
        // and therefore not every loop iteration will produce output.
        Get ComWriteString Of hoStream sPlainText To iSuccess
        Get ComDataAvailable Of hoStream To bTemp1
        If (bTemp1 = True) Begin
            Get ComReadBytesENC Of hoStream "hex" To sCipherText
            Showln sCipherText
            Get ComAppend Of hoEStrings sCipherText To iSuccess
        End

    Loop

    // Tell the background task that the stream has ended.
    Get ComWriteClose Of hoStream To iSuccess

    // Let's make sure the background task finished.
    // It should already be the case that the task is finished.
    While ((ComFinished(hoTask)) <> True)
        Send ComSleepMs To hoTask 20
    Loop

    // Get any remaining data available from the stream.
    Get ComDataAvailable Of hoStream To bTemp1
    If (bTemp1 = True) Begin
        Get ComReadBytesENC Of hoStream "hex" To sCipherText
        Showln sCipherText
        Get ComAppend Of hoEStrings sCipherText To iSuccess
    End

    Get ComTaskSuccess Of hoTask To bTemp1
    If (bTemp1 <> True) Begin
        Showln "async encryption failed:"
        Get ComResultErrorText Of hoTask To sTemp1
        Showln sTemp1
        Move False To iSuccess
    End

    Send Destroy of hoTask

    Showln "-- encrypt finished --"

    // Now decrypt to return the original.

    // Reset the stream object so it can be used again.
    Send ComReset To hoStream

    // Start a background task that will decrypt a stream.
    Get pvComObject of hoStream to vStream
    Get ComDecryptStreamAsync Of hoCrypt vStream To vTask
    If (IsComObject(vTask)) Begin
        Get Create (RefClass(cComChilkatTask)) To hoTask
        Set pvComObject Of hoTask To vTask
    End
    Get ComRun Of hoTask To iSuccess

    Get ComCount Of hoEStrings To n
    For i From 0 To (n - 1)
        Get ComGetString Of hoEStrings i To sTemp1
        Get ComWriteBytesENC Of hoStream sTemp1 "hex" To iSuccess
        Get ComDataAvailable Of hoStream To bTemp1
        If (bTemp1 = True) Begin
            Get ComReadString Of hoStream To sPlainText
            Showln sPlainText
        End

    Loop

    // Tell the background task that the stream has ended.
    Get ComWriteClose Of hoStream To iSuccess

    // Let's make sure the background task finished.
    // It should already be the case that the task is finished.
    While ((ComFinished(hoTask)) <> True)
        Send ComSleepMs To hoTask 20
    Loop

    // Get any remaining data available from the stream.
    Get ComDataAvailable Of hoStream To bTemp1
    If (bTemp1 = True) Begin
        Get ComReadString Of hoStream To sPlainText
        Showln sPlainText
    End

    Get ComTaskSuccess Of hoTask To bTemp1
    If (bTemp1 <> True) Begin
        Showln "async decryption failed:"
        Get ComResultErrorText Of hoTask To sTemp1
        Showln sTemp1
        Move False To iSuccess
    End

    Send Destroy of hoTask

    Showln "-- decrypt finished --"


End_Procedure