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Glossary Security

TLS

TLS (Transport Layer Security) is the cryptographic protocol that encrypts and authenticates connections, including HTTPS, email and VPNs.

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In more detail

TLS is the successor to SSL, whose versions are all retired. A handshake agrees on keys and checks the server's Digital certificate, then the data is encrypted with a fast symmetric cipher. TLS 1.3 (2018) is the current version; TLS 1.0 and 1.1 are deprecated. See How HTTPS and TLS Work.

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SSL Certificate Checker

Check any domain's SSL/TLS certificate details server-side — issuer, subject, expiry date, and SAN list.

Security Headers Analyzer

Check a website's HTTP security headers (HSTS, Content-Security-Policy, X-Content-Type-Options, Referrer-Policy, Permissions-Policy.

See also

  • Glossary HTTPS
    HTTPS is HTTP sent over an encrypted TLS connection, which keeps traffic private and confirms the identity of the server.
  • Glossary Digital certificate
    A digital certificate is a signed file that links a public key to an identity, such as a domain name, so others can trust that key.
  • Glossary Encryption
    Encryption is the process of scrambling data with a key so that only someone with the right key can read it.
  • Guide How HTTPS and TLS Work
    How the TLS 1.3 handshake, key exchange and certificate chain make a connection private and authenticated.
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