Module 12
TLS handshake and certificates
How a connection becomes private and trusted. Step through the TLS 1.3 handshake, follow a certificate chain to its root, and see what an eavesdropper still learns.
Start lesson 1
What does the padlock promise? · 6 min · free, no account
SecurityOpen now
What you'll operate
- The TLS 1.3 handshake
- Certificates and chains of trust
- What an observer can still see
- lessons
- 6
- minutes
- 49
Lessons in this module
- 1What does the padlock promise?See what TLS, the protection behind the padlock, does on an open network, and what it was never meant to do.Free, no account6 min
- 2How does a connection become private in one round trip?Play the TLS 1.3 handshake in its real order and see which messages are already encrypted.Plus8 min
- 3Why can't a recording be decrypted later?Watch two sides build a secret that never crosses the network, then see what resumption and 0-RTT trade away.Plus9 min
- 4What is inside a certificate?Read a certificate field by field and decide which names it is valid for.Plus8 min
- 5Why trust a server you have never met?Follow a certificate chain to a root your device already trusts, and find the check that fails when it breaks.Plus9 min
- 6What can someone on the path still see or do?Read a TLS 1.3 connection the way an observer does, then watch a downgrade attempt fail.Plus9 min
Lesson 1 is open to everyone, with no account. The other lessons in this module are part of Plus.