WhatsApp has a great reputation for secure end-to-end communications. It also offers a ‘chat backup’ facility to save conversations to Google Drive or iCloud. Really useful if you are swapping your phone, resetting it or whatever. The trouble is that they are sitting out on the web unencrypted.
Now you can also run Whatsapp on your PC or Mac. Just download the program, run it and follow the instructions to link your phone. It will then mirror your phone which is still needed to connect to WhatsApp. I find it much easier to copy photos and generally keep up to date.