(Delphi ActiveX) Streaming Decrypt HTTP Response

If the an encrypted file was previously uploaded, this example demonstrates how to download and decrypt in a streaming way.

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
rest: TChilkatRest;
bTls: Integer;
port: Integer;
bAutoReconnect: Integer;
success: Integer;
responseStatusCode: Integer;
errResponse: WideString;
crypt: TChilkatCrypt2;
receiveStream: TChilkatStream;
decryptStream: TChilkatStream;
decryptStreamTask: IChilkatTask;

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

rest := TChilkatRest.Create(Self);

bTls := 1;
port := 443;
bAutoReconnect := 1;
success := rest.Connect('chilkatdownload.com',port,bTls,bAutoReconnect);

// Send the request to download a file.
success := rest.SendReqNoBody('GET','/9.5.0.83/chilkat-9.5.0-python-3.8-x64.zip');
if (success <> 1) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

// Read the response header.
responseStatusCode := rest.ReadResponseHeader();
if (responseStatusCode < 0) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Response status code = ' + IntToStr(responseStatusCode));

// We expect a 200 response status if the JPG data is coming.
// Otherwise, we'll get a string response body with an error message(or no response body).
if (responseStatusCode <> 200) then
  begin
    errResponse := rest.ReadRespBodyString();
    if (rest.LastMethodSuccess <> 1) then
      begin
        Memo1.Lines.Add(rest.LastErrorText);
      end
    else
      begin
        Memo1.Lines.Add(errResponse);
      end;
    Exit;
  end;

// Create an object for decrypting.
// This example will use "none" for the encryption algorithm, which means it's just a pass-through.
// Typically you would set the decrypt properties, such as secret key, IV, key length, padding scheme, cipher mode..
crypt := TChilkatCrypt2.Create(Self);
crypt.CryptAlgorithm := 'none';

// The following settings are ignored in this test because our CryptAlgorithm is "none".
// However, if you were truly decrypting, you might set CryptAlgorithm = "aes".
crypt.CipherMode := 'cbc';
crypt.KeyLength := 128;
crypt.SetEncodedKey('000102030405060708090A0B0C0D0E0F','hex');
crypt.SetEncodedIV('000102030405060708090A0B0C0D0E0F','hex');

receiveStream := TChilkatStream.Create(Self);
// The decryptStream's source will be the receiveStream.
decryptStream := TChilkatStream.Create(Self);

// The decrypt stream's sink will be a file.
decryptStream.SinkFile := 'qa_output/chilkat-9.5.0-python-3.8-x64.zip';
decryptStream.SetSourceStream(receiveStream.ControlInterface);

// Create and run a background async task to decrypt incoming data and write to a file.
decryptStreamTask := crypt.DecryptStreamAsync(decryptStream.ControlInterface);
success := decryptStreamTask.Run();

success := rest.ReadRespBodyStream(receiveStream.ControlInterface,1);
if (success <> 1) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Successfully received the .zip file.');
end;