(Delphi DLL) Streaming Encryption

Encrypt and decrypt using a stream.

Chilkat for Delphi Downloads Chilkat non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, StringArray, Task, Stream, Crypt2;

...

procedure TForm1.Button1Click(Sender: TObject);
var
crypt: HCkCrypt2;
ivHex: PWideChar;
keyHex: PWideChar;
plainText: PWideChar;
stream: HCkStream;
eStrings: HCkStringArray;
task: HCkTask;
success: Boolean;
cipherText: PWideChar;
i: Integer;
n: Integer;

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

crypt := CkCrypt2_Create();

// Setup encryption using the chacha20 algorithm...
CkCrypt2_putCryptAlgorithm(crypt,'chacha20');
CkCrypt2_putKeyLength(crypt,256);
CkCrypt2_putEncodingMode(crypt,'hex');
ivHex := '000000000000000000000002';
CkCrypt2_SetEncodedIV(crypt,ivHex,'hex');
CkCrypt2_putInitialCount(crypt,42);
keyHex := '1c9240a5eb55d38af333888604f6b5f0473917c1402b80099dca5cbc207075c0';
CkCrypt2_SetEncodedKey(crypt,keyHex,'hex');

plainText := 'The quick brown fox jumped over the lazy dog.' + #13#10;

stream := CkStream_Create();

// We'll save the encrypted output in eStrings to demonstrate streaming decryption next.
eStrings := CkStringArray_Create();

// Start a background task that will encrypt a stream.
task := CkCrypt2_EncryptStreamAsync(crypt,stream);
success := CkTask_Run(task);

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

for i := 1 to 10 do
  begin
    // Note: An encryption algorithm's block size will cause buffering,
    // and therefore not every loop iteration will produce output.
    success := CkStream_WriteString(stream,plainText);
    if (CkStream_getDataAvailable(stream) = True) then
      begin
        cipherText := CkStream__readBytesENC(stream,'hex');
        Memo1.Lines.Add(cipherText);
        success := CkStringArray_Append(eStrings,cipherText);
      end;
  end;

// Tell the background task that the stream has ended.
success := CkStream_WriteClose(stream);

// Let's make sure the background task finished.
// It should already be the case that the task is finished.
while (CkTask_getFinished(task) <> True) do
  begin
    CkTask_SleepMs(task,20);
  end;

// Get any remaining data available from the stream.
if (CkStream_getDataAvailable(stream) = True) then
  begin
    cipherText := CkStream__readBytesENC(stream,'hex');
    Memo1.Lines.Add(cipherText);
    success := CkStringArray_Append(eStrings,cipherText);
  end;

if (CkTask_getTaskSuccess(task) <> True) then
  begin
    Memo1.Lines.Add('async encryption failed:');
    Memo1.Lines.Add(CkTask__resultErrorText(task));
    success := False;
  end;

CkTask_Dispose(task);

Memo1.Lines.Add('-- encrypt finished --');

// Now decrypt to return the original.

// Reset the stream object so it can be used again.
CkStream_Reset(stream);

// Start a background task that will decrypt a stream.
task := CkCrypt2_DecryptStreamAsync(crypt,stream);
success := CkTask_Run(task);

n := CkStringArray_getCount(eStrings);
for i := 0 to n - 1 do
  begin
    success := CkStream_WriteBytesENC(stream,CkStringArray__getString(eStrings,i),'hex');
    if (CkStream_getDataAvailable(stream) = True) then
      begin
        plainText := CkStream__readString(stream);
        Memo1.Lines.Add(plainText);
      end;
  end;

// Tell the background task that the stream has ended.
success := CkStream_WriteClose(stream);

// Let's make sure the background task finished.
// It should already be the case that the task is finished.
while (CkTask_getFinished(task) <> True) do
  begin
    CkTask_SleepMs(task,20);
  end;

// Get any remaining data available from the stream.
if (CkStream_getDataAvailable(stream) = True) then
  begin
    plainText := CkStream__readString(stream);
    Memo1.Lines.Add(plainText);
  end;

if (CkTask_getTaskSuccess(task) <> True) then
  begin
    Memo1.Lines.Add('async decryption failed:');
    Memo1.Lines.Add(CkTask__resultErrorText(task));
    success := False;
  end;

CkTask_Dispose(task);

Memo1.Lines.Add('-- decrypt finished --');

CkCrypt2_Dispose(crypt);
CkStream_Dispose(stream);
CkStringArray_Dispose(eStrings);

end;