フリー問題

問題文

A session is encrypted and the site has chosen not to decrypt it. Which visible material still lets one client be told apart from another?

選択肢

1. The set of versions and options the server offers in its reply, since that message goes out before any key is in place and different clients draw different replies from the same server
2. The set of versions and options the client offers in its opening message, since that message goes out before any key is in place and different clients offer different sets
3. The name of the certificate authority in the chain the client accepts, since that name goes out before any key is in place and different clients accept different authorities
4. The length of every message after the keys are in place, since those lengths go out unchanged by the encryption and different clients produce different lengths for the same request