Definition
Certificate Transparency (CT) is a public logging system requiring trusted CAs to publish issued certificates. Organizations monitor CT logs for unauthorized certificate issuance on their domains.
Key Points
- 2026-10-06: Google recommended CT monitoring after cctld-registry-hijack — near real-time alert for unexpected cert issuance (2026-10-07-google-cctld-hijack-chrome-response)
- Tools like crt.sh enable domain owners to audit .gh/.sl/.as certificates
- CT enabled detection of counterfeit Google certs; Google cannot guarantee complete inventory