What is the purpose of extended master key extension/session hash?

 The extended master key extension/session hash is a feature introduced in TLS 1.3 to prevent a Man-in-the-Middle attack/disclosure of the client-server communication. It works by generating a unique session hash for each connection, which is derived from the master key and other parameters. This session hash is then used to authenticate the application data and the end-of-handshake messages, ensuring that no one can tamper with or eavesdrop on the communication. References: Check Point Security Expert R81 Course, TLS 1.3 RFC