Open Zip and Save Password Protected

Open a .zip (non-encrypted) and then save it password-protected.

Download: Chilkat .NET Assemblies

Chilkat.Zip zip = new Chilkat.Zip();

bool success;

//  Any string unlocks the component for the 1st 30-days.
success = zip.UnlockComponent("Anything for 30-day trial");
if (success != true) {
    MessageBox.Show(zip.LastErrorText);
    return;
}

success = zip.OpenZip("test.zip");
if (success != true) {
    MessageBox.Show(zip.LastErrorText);
    return;
}

//  Set a password and indicate that password protection
//  should be used when writing the .zip
zip.EncryptPassword = "secret";
zip.PasswordProtect = true;

//  Write the zip (overwrites test.zip)

success = zip.WriteZipAndClose();
if (success != true) {
    MessageBox.Show(zip.LastErrorText);
    return;
}

MessageBox.Show("Zip Re-Written with Password Protection!");