During which handshake phase is `change_cipher_spec` sent, and does it belong to the Handshake Protocol?

Answer

Phase 4, and it is not a Handshake Protocol message

Options - A. Phase 4, and it is not a Handshake Protocol message - B. Phase 4, and it is the final Handshake Protocol message - C. Phase 1, as part of establishing security capabilities - D. Phase 2, immediately before server_done Why - A. Correct. It is sent at the finish, by the separate Change Cipher Spec Protocol, with its own record content type. - B. Right phase, wrong protocol — and this half-right option is the one the question is built to catch. The last Handshake message is `finished`. - C. Phase 1 carries only the two hello messages. There is no cipher state to switch yet. - D. Phase 2 ends with server_done. Switching cipher state there would precede the key exchange it depends on.

Stallings & Brown 5e ch22 §22.3 — the SSLv3 / TLS 1.2-lineage handshake (see the callout)