(Delphi ActiveX) Encrypt Already Existing Zip

To encrypt an already existing non-encrypted .zip, the application must open the .zip, set the encryption related properties, and then re-write.

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
zip: TChilkatZip;
success: Integer;
numFilesUnzipped: Integer;

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

zip := TChilkatZip.Create(Self);

// Open an unencrypted .zip
success := zip.OpenZip('qa_data/zips/test.zip');
if (success <> 1) then
  begin
    Memo1.Lines.Add(zip.LastErrorText);
    Exit;
  end;

// Unzip to a temp directory.
numFilesUnzipped := zip.Unzip('qa_output/tmp');
if (numFilesUnzipped < 0) then
  begin
    Memo1.Lines.Add(zip.LastErrorText);
    Exit;
  end;

// Clear the zip object.
zip.NewZip('qa_output/aesTest.zip');

// Indicate that 128-bit AES encryption is to be used when writing the .zip
zip.Encryption := 4;
zip.EncryptKeyLength := 128;

// Set the password.
zip.EncryptPassword := 'secret';

// Append the files.
zip.AppendFromDir := 'qa_output/tmp';
success := zip.AppendFiles('*.*',1);
if (success <> 1) then
  begin
    Memo1.Lines.Add(zip.LastErrorText);
    Exit;
  end;

// Write the .zip and close it.
success := zip.WriteZipAndClose();
if (success <> 1) then
  begin
    Memo1.Lines.Add(zip.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Success.');
end;