Remove Zip Encryption

Opens an encrypted zip archive and rewrites it with no encrypton.

Download Chilkat 32-bit Zip ActiveX (.msi) (includes objects for .zip, .gz, .bz2, and .Z)

Download All 32-bit Chilkat ActiveX Components (.zip)

Download All 64-bit Chilkat ActiveX Components (.zip)

uses
    Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
    Dialogs, StdCtrls,
    ChilkatZip2Lib_TLB,
    OleCtrls;

...

procedure TForm1.Button1Click(Sender: TObject);
var
zip: TChilkatZip2;
success: Integer;

begin
zip := TChilkatZip2.Create(Self);

//  Any string unlocks the component for the 1st 30-days.
success := zip.UnlockComponent('Anything for 30-day trial');
if (success <> 1) then
  begin
    ShowMessage(zip.LastErrorText);
    Exit;
  end;

//  An encrypted .zip may be "opened" without providing a
//  password.  However, the contents cannot be unzipped
//  without setting the DecryptPassword property.
success := zip.OpenZip('myEncrypted.zip');
if (success <> 1) then
  begin
    ShowMessage(zip.LastErrorText);
    Exit;
  end;

//  Set the DecryptPassword property:
zip.DecryptPassword := 'myPassword';

//  Indicate that when the zip is to be written again,
//  it should be neither AES encrypted, or password-protected
//  (i.e. older Zip 2.0 encryption)
zip.Encryption := 0;
zip.PasswordProtect := 0;

//  Set the filename of the new unencrypted .zip to be written:
zip.FileName := 'unencrypted.zip';

//  Write the unencrypted .zip
//  What happens during WriteZipAndClose?  --
//  The encrypted entries from myEncrypted.zip are streamed in,
//  decrypted, and then written out directly into unencrypted.zip
//  In other words, internally the component is smart enough
//  to stream the data from the existing .zip to the new .zip
//  automatically, decrypting in the process..
success := zip.WriteZipAndClose();
if (success <> 1) then
  begin
    ShowMessage(zip.LastErrorText);
    Exit;
  end;

ShowMessage('OK!');

end;