I apologize, I missed that the question was tagged Django. It seems the best option for implementing this in Django is the XSendfile method which is supported by apache. This thread compares some methods and includes examples like this one;

@login_required
def serve_file(request, filename):
    fullname = myapp.settings.PRIVATE_AREA+filename
    try:
        f = file(fullname, "rb")
    except Exception, e:
        return page_not_found(request, template_name='404.html')
    try:
        wrapper = FileWrapper(f)
        response = HttpResponse(wrapper, mimetype=mimetypes.guess_type(filename)[0])
        response['Content-Length'] = os.path.getsize(fullname)
        response['Content-Disposition'] = 'attachment; filename={0}'.format(filename)
        return response
    except Exception, e:
        return page_not_found(request, template_name='500.html')