(Delphi DLL) 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 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, Rest, Stream, Task, Crypt2;

...

procedure TForm1.Button1Click(Sender: TObject);
var
rest: HCkRest;
bTls: Boolean;
port: Integer;
bAutoReconnect: Boolean;
success: Boolean;
responseStatusCode: Integer;
errResponse: PWideChar;
crypt: HCkCrypt2;
receiveStream: HCkStream;
decryptStream: HCkStream;
decryptStreamTask: HCkTask;

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

rest := CkRest_Create();

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

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

// Read the response header.
responseStatusCode := CkRest_ReadResponseHeader(rest);
if (responseStatusCode < 0) then
  begin
    Memo1.Lines.Add(CkRest__lastErrorText(rest));
    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 := CkRest__readRespBodyString(rest);
    if (CkRest_getLastMethodSuccess(rest) <> True) then
      begin
        Memo1.Lines.Add(CkRest__lastErrorText(rest));
      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 := CkCrypt2_Create();
CkCrypt2_putCryptAlgorithm(crypt,'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".
CkCrypt2_putCipherMode(crypt,'cbc');
CkCrypt2_putKeyLength(crypt,128);
CkCrypt2_SetEncodedKey(crypt,'000102030405060708090A0B0C0D0E0F','hex');
CkCrypt2_SetEncodedIV(crypt,'000102030405060708090A0B0C0D0E0F','hex');

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

// The decrypt stream's sink will be a file.
CkStream_putSinkFile(decryptStream,'qa_output/chilkat-9.5.0-python-3.8-x64.zip');
CkStream_SetSourceStream(decryptStream,receiveStream);

// Create and run a background async task to decrypt incoming data and write to a file.
decryptStreamTask := CkCrypt2_DecryptStreamAsync(crypt,decryptStream);
success := CkTask_Run(decryptStreamTask);

success := CkRest_ReadRespBodyStream(rest,receiveStream,True);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkRest__lastErrorText(rest));
    Exit;
  end;

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

CkRest_Dispose(rest);
CkCrypt2_Dispose(crypt);
CkStream_Dispose(receiveStream);
CkStream_Dispose(decryptStream);

end;