All visualizationsSystem Design · 33 of 34
The TLS handshake — the secret behind the padlock
Prove who you’re talking to, agree on a secret in public, then switch to fast ciphers — all before one byte of your data moves.
💡
THE BIG IDEA
Every https:// page starts with two strangers solving an impossible-sounding puzzle: verify each other’s identity and agree on a secret code, while assuming everyone can hear them. The handshake does it in milliseconds — certificates for identity, one-way math for the secret, symmetric ciphers for speed. Watch it happen, and learn exactly what the padlock does and does not promise.
Press ▶ Play to watch it run step by step, or use the arrow buttons to go at your own pace.
1
You open https://yourbank.in. Two problems must be solved before your password may travel: is this REALLY the bank? And how do two strangers agree on a secret code while everyone can hear them?
Identity and secrecy. The handshake solves both, in that order, in milliseconds. (You will also hear this called SSL — that is the protocol’s retired ancestor; everything modern is TLS.)
🧑‍💻You → https://
🌐Your browser
🏦Web server
handling requesthealthyjust added
1/10
UP NEXT IN SYSTEM DESIGN
Inside the UPI rail — what happens in the two seconds after you scan
Follow ₹499 across four parties, then watch it get debited, fail to arrive, and come back by law.
SQL vs NoSQL — One Read, Two WorldsInside the UPI rail — what happens in the two seconds after you scan