What it is
Transport Layer Security (TLS), formerly known as Secure Sockets Layer (SSL), is the protocol that secures data in transit between clients and servers. It establishes an encrypted channel that preserves confidentiality, integrity, and authenticity. During the TLS handshake, parties negotiate cryptographic parameters, validate digital certificates issued by trusted certificate authorities, and establish session keys. Modern TLS versions support advanced cipher suites, forward secrecy, and application-layer protocol negotiation for performance. TLS underpins HTTPS, secure email delivery (STARTTLS), VPN tunnels, and many API integrations. Proper implementation requires certificate lifecycle management, strong cipher configuration, and protection against downgrade attacks. Deprecated SSL versions and weak ciphers remain common misconfigurations that attackers exploit to intercept or manipulate traffic. While TLS is often transparent to end users, it is integral to trust on the modern internet and within private networks.
Why it matters
Without TLS, sensitive data like credentials, payment information, and personal records could be intercepted or altered during transmission. Regulatory frameworks and customer expectations demand encrypted communications, and browsers now flag non-TLS sites as insecure.
How to reduce risk
- Enforce TLS 1.2 or higher with strong cipher suites and enable HTTP Strict Transport Security (HSTS) for web properties.
- Automate certificate issuance, renewal, and revocation using ACME-compatible services and centralized inventory.
- Monitor for certificate misconfigurations, expiring certs, and unauthorized issuance via Certificate Transparency logs.
- Terminate TLS at secure, patched endpoints and inspect traffic for anomalies within encrypted environments responsibly.