Introduction to SSL/TLS
SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are cryptographic protocols designed to provide secure communication over a computer network. While SSL is the older protocol that has been deprecated, TLS is its modern successor and is the standard used today.
Why SSL/TLS Matters
When you visit a website, your browser connects to the server and exchanges data. Without SSL/TLS, this data travels in plain text, meaning anyone intercepting the connection can read it. SSL/TLS encrypts this data, making it unreadable to attackers.
Key benefits include:
- Encryption — Data is encrypted in transit, protecting sensitive information like passwords and credit card numbers.
- Authentication — Verifies that you're connecting to the real server, not an impostor.
- Data Integrity — Ensures data hasn't been tampered with during transmission.
The SSL vs TLS Terminology
SSL 3.0 was the last version of SSL, released in 1996. It was found to have serious security vulnerabilities. TLS 1.0 was introduced in 1999 as SSL 3.1, and the protocol has been updated through TLS 1.3 (2018). Today, when people say "SSL certificate," they mean a certificate that uses the TLS protocol.
How It Works
The SSL/TLS handshake process establishes a secure connection:
- Client sends a "Hello" message with supported TLS versions and cipher suites.
- Server responds with its chosen cipher suite and its certificate.
- Client verifies the certificate against trusted root CAs.
- Both parties generate session keys for symmetric encryption.
- Secure communication begins using the negotiated parameters.