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Chapter 15. Using shared system certificates

The shared system certificates storage enables NSS, GnuTLS, OpenSSL, and Java to share a default source for retrieving system certificate anchors and block-list information. By default, the trust store contains the Mozilla CA list, including positive and negative trust. The system allows updating the core Mozilla CA list or choosing another certificate list.

15.1. The system-wide trust store

In RHEL, the consolidated system-wide trust store is located in the /etc/pki/ca-trust/ and /usr/share/pki/ca-trust-source/ directories. The trust settings in /usr/share/pki/ca-trust-source/ are processed with lower priority than settings in /etc/pki/ca-trust/.

Certificate files are treated depending on the subdirectory they are installed to. For example, trust anchors belong to the /usr/share/pki/ca-trust-source/anchors/ or /etc/pki/ca-trust/source/anchors/ directory.

Note

In a hierarchical cryptographic system, a trust anchor is an authoritative entity that other parties consider trustworthy. In the X.509 architecture, a root certificate is a trust anchor from which a chain of trust is derived. To enable chain validation, the trusting party must have access to the trust anchor first.

Additional resources

  • update-ca-trust(8) and trust(1) man pages

15.2. Adding new certificates

To acknowledge applications on your system with a new source of trust, add the corresponding certificate to the system-wide store, and use the update-ca-trust command.

Prerequisites

  • The ca-certificates package is present on the system.

Procedure

  1. To add a certificate in the simple PEM or DER file formats to the list of CAs trusted on the system, copy the certificate file to the /usr/share/pki/ca-trust-source/anchors/ or /etc/pki/ca-trust/source/anchors/ directory, for example: 

    # cp ~/certificate-trust-examples/Cert-trust-test-ca.pem /usr/share/pki/ca-trust-source/anchors/

  2. To update the system-wide trust store configuration, use the update-ca-trust command: 

    # update-ca-trust
Note

Even though the Firefox browser can use an added certificate without a prior execution of update-ca-trust, enter the update-ca-trust command after every CA change. Also note that browsers, such as Firefox, Chromium, and GNOME Web cache files, and you might have to clear your browser’s cache or restart your browser to load the current system certificate configuration.

Additional resources

  • update-ca-trust(8) and trust(1) man pages

15.3. Managing trusted system certificates

The trust command provides a convenient way for managing certificates in the shared system-wide trust store.

  • To list, extract, add, remove, or change trust anchors, use the trust command. To see the built-in help for this command, enter it without any arguments or with the --help directive: 

    $ trust
usage: trust command <args>...

Common trust commands are:
  list             List trust or certificates
  extract          Extract certificates and trust
  extract-compat   Extract trust compatibility bundles
  anchor           Add, remove, change trust anchors
  dump             Dump trust objects in internal format

See 'trust <command> --help' for more information

  • To list all system trust anchors and certificates, use the trust list command: 

    $ trust list
pkcs11:id=%d2%87%b4%e3%df%37%27%93%55%f6%56%ea%81%e5%36%cc%8c%1e%3f%bd;type=cert
    type: certificate
    label: ACCVRAIZ1
    trust: anchor
    category: authority

pkcs11:id=%a6%b3%e1%2b%2b%49%b6%d7%73%a1%aa%94%f5%01%e7%73%65%4c%ac%50;type=cert
    type: certificate
    label: ACEDICOM Root
    trust: anchor
    category: authority
...

  • To store a trust anchor into the system-wide trust store, use the trust anchor sub-command and specify a path to a certificate. Replace <path.to/certificate.crt> by a path to your certificate and its file name: 

    # trust anchor <path.to/certificate.crt>

  • To remove a certificate, use either a path to a certificate or an ID of a certificate: 

    # trust anchor --remove <path.to/certificate.crt>
# trust anchor --remove "pkcs11:id=<%AA%BB%CC%DD%EE>;type=cert"

Additional resources

  • All sub-commands of the trust commands offer a detailed built-in help, for example: 

    $ trust list --help
usage: trust list --filter=<what>

  --filter=<what>     filter of what to export
                        ca-anchors        certificate anchors
...
  --purpose=<usage>   limit to certificates usable for the purpose
                        server-auth       for authenticating servers
...

Additional resources

  • update-ca-trust(8) and trust(1) man pages