doc/book/cookbook/encryption.md

@@ -104,5 +104,8 @@ Implementations are very specific to the various applications. Examples:
   in Matrix are probably encrypted using symmetric encryption, with a key that is
   distributed in the end-to-end encrypted message that contains the link to the object.
 
-- Aerogramme: use the user's password as a key to decrypt data in the user's bucket
+- XMPP: clients normally support either OMEMO / OpenPGP for the E2EE of user
+  messages. Media files are encrypted per
+  [XEP-0454](https://xmpp.org/extensions/xep-0454.html).
 
+- Aerogramme: use the user's password as a key to decrypt data in the user's bucket