http://ssd.iykpqm7jiradoeezzkhj7c4b33g4hbgfwelht2evxxeicbpjy44c7ead.onion/ps/module/guide-pratique-chiffrer-votre-iphone
However, if you use any sort of iWork collaboration, like working with others on a document in Pages or Numbers, those files are not end-to-end encrypted. Likewise, if you share a file or folder using the "anyone with the link" option from an app, like Files or Photos, then that is no longer end-to-end encrypted.