(Delphi DLL) 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 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, Zip;

...

procedure TForm1.Button1Click(Sender: TObject);
var
zip: HCkZip;
success: Boolean;
numFilesUnzipped: Integer;

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

zip := CkZip_Create();

// Open an unencrypted .zip
success := CkZip_OpenZip(zip,'qa_data/zips/test.zip');
if (success <> True) then
  begin
    Memo1.Lines.Add(CkZip__lastErrorText(zip));
    Exit;
  end;

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

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

// Indicate that 128-bit AES encryption is to be used when writing the .zip
CkZip_putEncryption(zip,4);
CkZip_putEncryptKeyLength(zip,128);

// Set the password.
CkZip_putEncryptPassword(zip,'secret');

// Append the files.
CkZip_putAppendFromDir(zip,'qa_output/tmp');
success := CkZip_AppendFiles(zip,'*.*',True);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkZip__lastErrorText(zip));
    Exit;
  end;

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

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

CkZip_Dispose(zip);

end;