13/09/2025
🔒 What Makes HTTPS “Secure”? (TLS Handshake in 6 Steps)
Most people know the little “s” in https:// stands for secure, but what actually makes it secure? The answer: TLS (Transport Layer Security) — the protocol that encrypts your connection and keeps your data private.
Here’s the TLS 1.2 handshake, simplified:
1️⃣ TCP Handshake – First, your browser sets up a reliable connection with the server (SYN → SYN-ACK → ACK).
2️⃣ ClientHello – Your browser says hello, sharing supported TLS versions, cipher suites, and extras like SNI/ALPN.
3️⃣ ServerHello + Certificate – The server replies with its chosen cipher suite and sends a digital certificate with its public key.
4️⃣ Certificate Validation – Your browser checks that the certificate is signed by a trusted CA and hasn’t been tampered with.
5️⃣ Key Exchange – Your browser generates a pre-master secret, encrypts it with the server’s public key, and sends it over.
6️⃣ Session Key Generation – Both sides independently generate session keys from the shared secret. Now, all communication is encrypted (fast, symmetric encryption).
💡 Next time you see the 🔒 icon, remember — your browser and the server just did this entire handshake in milliseconds to keep your data safe.
See the full article https://medium.com//how-the-tls-1-2-handshake-works-a-simple-step-by-step-guide-95635edd45c4