# SSH Certificate User Authentication
FileMage Gateway supports SSH certificate user authentication for the SFTP listener. To enable it, upload your certificate authority public key to the server and set the sftp_trusted_user_ca_keys configuration in the application configuration file to the path of the uploaded file.
During authentication, if a certificate is presented, the application will validate that the certificate is valid and signed by one of the configured trusted CAs and that the principal matches the user logging in. The
source-address extension will also be verified.