(Delphi ActiveX) Streaming Encryption

Encrypt and decrypt using a stream.

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

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
crypt: TChilkatCrypt2;
ivHex: WideString;
keyHex: WideString;
plainText: WideString;
stream: TChilkatStream;
eStrings: TCkStringArray;
task: IChilkatTask;
success: Integer;
cipherText: WideString;
i: Integer;
n: Integer;

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

crypt := TChilkatCrypt2.Create(Self);

// Setup encryption using the chacha20 algorithm...
crypt.CryptAlgorithm := 'chacha20';
crypt.KeyLength := 256;
crypt.EncodingMode := 'hex';
ivHex := '000000000000000000000002';
crypt.SetEncodedIV(ivHex,'hex');
crypt.InitialCount := 42;
keyHex := '1c9240a5eb55d38af333888604f6b5f0473917c1402b80099dca5cbc207075c0';
crypt.SetEncodedKey(keyHex,'hex');

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

stream := TChilkatStream.Create(Self);

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

// Start a background task that will encrypt a stream.
task := crypt.EncryptStreamAsync(stream.ControlInterface);
success := task.Run();

// 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 := stream.WriteString(plainText);
    if (stream.DataAvailable = 1) then
      begin
        cipherText := stream.ReadBytesENC('hex');
        Memo1.Lines.Add(cipherText);
        success := eStrings.Append(cipherText);
      end;
  end;

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

// Let's make sure the background task finished.
// It should already be the case that the task is finished.
while (task.Finished <> 1) do
  begin
    task.SleepMs(20);
  end;

// Get any remaining data available from the stream.
if (stream.DataAvailable = 1) then
  begin
    cipherText := stream.ReadBytesENC('hex');
    Memo1.Lines.Add(cipherText);
    success := eStrings.Append(cipherText);
  end;

if (task.TaskSuccess <> 1) then
  begin
    Memo1.Lines.Add('async encryption failed:');
    Memo1.Lines.Add(task.ResultErrorText);
    success := 0;
  end;

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

// Now decrypt to return the original.

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

// Start a background task that will decrypt a stream.
task := crypt.DecryptStreamAsync(stream.ControlInterface);
success := task.Run();

n := eStrings.Count;
for i := 0 to n - 1 do
  begin
    success := stream.WriteBytesENC(eStrings.GetString(i),'hex');
    if (stream.DataAvailable = 1) then
      begin
        plainText := stream.ReadString();
        Memo1.Lines.Add(plainText);
      end;
  end;

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

// Let's make sure the background task finished.
// It should already be the case that the task is finished.
while (task.Finished <> 1) do
  begin
    task.SleepMs(20);
  end;

// Get any remaining data available from the stream.
if (stream.DataAvailable = 1) then
  begin
    plainText := stream.ReadString();
    Memo1.Lines.Add(plainText);
  end;

if (task.TaskSuccess <> 1) then
  begin
    Memo1.Lines.Add('async decryption failed:');
    Memo1.Lines.Add(task.ResultErrorText);
    success := 0;
  end;

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