Has the WhatsApp code been audited by trusted third parties? I know it's not quite as good as it being open source, but if we had people we trust audit it, that

Has the WhatsApp code been audited by trusted third parties? I know it's not quite as good as it being open source, but if we had people we trust audit it, that seems like a good step. Also, disassembly and teardown. I think something this big needs people to really really scrutinise it.