Certificates Tab
The following feature is new in Ignition version
8.1.0
Click here to check out the other new features
The Certificates tab shows the trusted certificates for the OPC UA client and server on the gateway. From this tab the certificates can be examined by clicking the
More Info 
icon. The certificates can be downloaded by clicking the
Download button. This will perform the same action as downloading a certificate from the
Client tab as described above.

Clicking the Regenerate button for each certificate will create a new certificate.
Regenerate Current Certificates
All certificates have a definitive live span. For example, the default life span for an Ignition-generated OPC UA certificate is three years. Any OPC UA connection, even the default loopback connection to Ignition's own server, will stop working if the certificate expires or is invalid.
Regenerating the certificates creates a new certificate with an expiration date set for three years later. If your private key is somehow compromised, regenerating a Client or Server certificate also ensures that the private key will no longer work with the Ignition Gateway.
Newly regenerated certificates are automatically trusted by the Gateway issuing them.
Note that regenerating a server certificate will require that the OPC UA module is restarted.
The following feature is new in Ignition version
8.1.8
Click here to check out the other new features
Regenerating a client certificate will allow you to specify the duration of the new certificate.
In addition, regenerating a server certificate will allow you to specify the duration as well as the DNS names and IP addresses to be included in the Subject Alternate Name (SAN) fields. 