15.7. Changing the Trust Settings of a CA Certificate

Certificate System subsystems use the CA certificates in their certificate databases to validate certificates received during an SSL-enabled communication.
It can be necessary to change the trust settings on a CA stored in the certificate database, temporarily or permanently. For example, if there is a problem with access or compromised certificates, marking the CA certificate as untrusted prevents entities with certificates signed by that CA from authenticating to the Certificate System. When the problem is resolved, the CA can be marked as trusted again.
To untrust a CA permanently, consider removing its certificate from the trust database. For instructions, see Section 15.6.3, “Deleting Certificates from the Database”.

15.7.1. Changing Trust Settings through the Console

To change the trust setting of a CA certificate, do the following:
  1. Open the subsystem console.
    pkiconsole https://server.example.com:admin_port/subsystem_type
  2. In the Configuration tab, System Keys and Certificates from the left navigation tree.
  3. Select the CA certificates tab.
  4. Select the CA certificate to modify, and click Edit.
  5. A prompt opens which reads The Certificate chain is (un)trusted, are you sure you want to (un)trust it?
    Clicking yes changes the trust setting of the certificate chain; pressing no preserves the original trust relationship.

15.7.2. Changing Trust Settings Using certutil

To change the trust setting of a certificate using certutil, do the following:
  1. Open the instance's certificate databases directory.
    cd /var/lib/instance_name/alias
  2. List the certificates in the database by running the certutil with the -L option. For example:
    certutil -L -d .
    
    Certificate Authority - Example Domain    CT,c,
    subsystemCert cert-subsystem              u,u,u
    Server-Cert cert-example                  u,u,u
  3. Change the trust settings for the certificate by running the certutil with the -M option.
    certutil -M -n cert_nickname -t trust -d .
    For example:
    certutil -M -n "Certificate Authority - Example Domain" -t TCu,TCu,TCu -d .
  4. List the certificates again to confirm that the certificate trust was changed.
    certutil -L -d .
    
    Certificate Authority - Example Domain    CTu,CTu,CTu
    subsystemCert cert-subsystem              u,u,u
    Server-Cert cert-example                  u,u,u
For information about using the certutil command, see http://www.mozilla.org/projects/security/pki/nss/tools/certutil.html.