Simple definition
The certificate allows the browser to verify the identity of the site and to establish a connection HTTPS Numbered.
Technical definition
It is signed by a certification authority and includes the subject, the names covered, the public key and a period of validity. TLS then uses this key in the establishment of the secure session.
- Browser Starts HTTPS
- Web server Presents its certificate
- TLS certificate Identity + public key
- Validation Chain, name and validity
- TLS session Negotiated encryption
The certificate helps authenticate the server; session encryption keys are negotiated during the TLS handshake.
What is it used for?
Secure websites, messaging services, VPN, LDAP and internal applications.
Practical example
The browser accepts the certificate of boiteaoutilsinformatique.fr Because his name matches and his chain goes back to a recognized authority.
Common issues
- Certificate expired
- Domain name not covered
- Incomplete intermediate chain
- Self-signed certificate not approved
Related terms
Key takeaway: This entry explains the general operation of the term. Exact settings may vary depending on software, vendors and environments.