diff --git a/README.md b/README.md
index 7b88813..e31562a 100644
--- a/README.md
+++ b/README.md
@@ -6,6 +6,8 @@ The Public Certificate of the CA and its Private Key are ansible variables. Make
 
 ## Dependencies
 
+You need to have the `cryptography` python library available on the localhost and on the remote hosts.
+
 ## Generate a CA
 
 ### Generate a key
@@ -56,3 +58,5 @@ Then, don't forget to remode the file `ca.key`.
 
 
 ## How does it works ?
+
+The role check if the certificate already exist and is valid. If not, it will generate **on the localhost** the certificates and then copy them to the remote host and delate the local version.