12.5 TLS keys
TLS uses two types of secret keys. The Handshake Traffic Keys are are used for the encryption of the TLS handshake traffic. They are derived from the TLS secrets:
Alice’s key is derived from
server˙handshake˙traffic˙secretBob’s key is derived from
client˙handshake˙traffic˙secret
The Application Traffic Keys are used to encrypt the bulk application data that Bob and Alice transmit during their TLS session. Similar to handshake traffic keys, they are also generated from two different secrets:
server˙application˙traffic˙secretfor Alice’s keyclient˙application˙traffic˙secretfor Bob’s key
Alice uses her handshake traffic key to encrypt one or more messages to Bob during the TLS handshake: EncryptedExtensions and, optionally, CertificateRequest, Certificate, and CertificateVerify.
The EncryptedExtensions message contains a list of extensions not necessary for establishing...
