What it is
X.509 certificates are the backbone of public key infrastructure (PKI). They bind a public key to an entity�such as a domain, organization, or individual�and are issued by trusted certificate authorities. These certificates enable encryption via TLS/SSL and authentication, ensuring that users connect to genuine servers and not impostors.
Each certificate includes metadata such as the subject, issuer, validity period, and digital signature. Browsers and systems use CA trust chains to verify authenticity before establishing secure connections.
Why it matters
Without valid certificates, encrypted communications cannot be trusted. Misissued or expired certificates can cause outages, phishing opportunities, and man-in-the-middle attacks.
How to reduce risk
- Automate certificate issuance and renewal using ACME protocols such as Let�s Encrypt.
- Revoke compromised certificates immediately.
- Regularly audit CA trust stores.
- Use short-lived certificates to limit exposure.
- Enforce strict certificate pinning for critical systems.