Certifikatproblem

Certifikatproblem is a term in information technology describing issues with digital certificates used to establish trust in electronic communications and software. These certificates may secure TLS/SSL traffic, code signing, email security (S/MIME), or client/server authentication. A certificate problem occurs when a party cannot verify the certificate’s validity or its trust chain, leading to a failed trust decision or a warning.

Common causes include an expired certificate, a revoked certificate, or hostname mismatch. A broken certificate chain due to missing or misordered intermediates is also frequent. Other factors: use of a self-signed certificate in public contexts, outdated trust stores, clock drift on client or server, or weak algorithms such as SHA-1. Proxies or firewalls that resign or inspect TLS traffic can introduce problems.

Certificate problems typically result in failed secure connections, browser warnings such as Not Secure or Your connection is not private, service outages, or failed software validations. In enterprise environments, automated systems may halt deployment or fail to authenticate users or devices.

Troubleshooting involves inspecting the certificate details (issuer, subject, validity period, and SANs), verifying the certificate chain with tools such as openssl or browser diagnostics, checking system clocks, and validating revocation status via OCSP/CRL. It is also important to ensure the proper installation of intermediate certificates and to confirm that the hostname matches the certificate.

Resolutions include renewing or reissuing certificates, installing intermediates, correcting hostname configurations, updating trust stores, and aligning clocks. On the client side, trusting the issuing CA may be appropriate in controlled environments, but is generally discouraged. Preventive measures: automated certificate management (ACME/Let’s Encrypt), monitoring expiration, using CAA records, and avoiding mixed content or improper pinning.