[[enable-message-authentication]]
=== Enable Message Authentication

Message authentication verifies that a message has not been tampered with or corrupted in transit. 

To enable message authentication:

. Run the `syskeygen` tool from `ES_HOME` without any options:
+
[source, shell]
----------------
bin/shield/syskeygen
----------------
+
This creates a system key file in `CONFIG_DIR/shield/system_key`.

. Copy the genererated system key to the rest of the nodes in the cluster.

IMPORTANT: The system key is a symmetric key, so the same key must be on every node in the cluster.

Now that you've enabled message authentication, you might also want to <<enable-auditing, Enable Auditing>> to keep track of attempted and successful interactions with your Elasticsearch cluster. 
