diff --git a/README.md b/README.md
index e73303a..b96f961 100644
--- a/README.md
+++ b/README.md
@@ -11,6 +11,8 @@ It stores files and allows you to download them.
 Is that all? No. All the files are encrypted **by the browser**! It means that your files **never** leave your computer unencrypted.
 The administrator of the Lufi instance you use will not be able to see what is in your file, neither will your network administrator, or your ISP.
 
+The encryption key part of the URL is a anchor (Cf. [Fragment Identifier](https://en.wikipedia.org/wiki/Fragment_identifier)), that means this part is only processed client-side and does not reached the server. :-)
+
 ## License
 
 Lufi is licensed under the terms of the AGPL. See the [LICENSE](LICENSE) file.