TLS/SSL Study Note

Preface

In the third assignment of "Network Security Practice", we are asked to trace TLS/SSL traffic package. I am writing down my understanding of TLS/SSL after studying on Wikipedia and other sites.

Procedure

Objects

1. CLIENT A
2. SERVER A: serving the desired application services for CLIENT A
3. SERVER B: the server which issues digital certification for SERVER A

Steps

1. [CLIENT] → [SERVER A]
• request secure connection
• offer a list of supported cipher suites
2. [SERVER A] → [CLIENT]: send back followings:
• picked cipher/hash function
• its identification (digital certificate), mostly contains:
3. • servername
   • trusted certificate authority
   • public encryption key
4. [CLIENT] → [SERVER B]: check validity of SERVER A
5. [CLIENT] ←→ [SERVER A]: generate the session key
6. • [CLIENT] encrypts a random number using received public key, then send out the result
   • [SERVER B] decrypts with its private key, then get the random number
7. [CLIENT] ←→ [SERVER A]: start various application-layer communications by encrypting/decrypting with the picked hash function & the random number

Reference

• Transport Layer Security - Wikipedia