TLS — end of module

What this checks. That you can say exactly what a capture of a TLS connection still reveals, and what a certificate does and does not prove. You need 3 of 4 to pass, and every option is explained afterwards — including the ones you did not pick.

1. 1/4A browser warns before displaying anything. Which two items in the capture, compared against each other, establish why?

   Choose the evidence

   The server name in the ClientHello and the subject in the Certificate message

   The cipher suite list and the selected cipher

   The TCP window sizes at each end
2. 2/4In a modern TLS connection, which of these remains visible to somebody capturing the traffic?

   Tell two ideas apart

   The addresses and ports, the timing and sizes of records, and — unless encrypted ClientHello is in use — the server name in the SNI extension

   Nothing at all — the connection is opaque from the first byte

   The full request and response, since only the certificate is encrypted
3. 3/4Someone says 'the padlock means the site is legitimate'. Why is that wrong?

   Say why an answer is wrong

   A certificate binds a key to a NAME, and says nothing about whether the operator of that name is honest

   Certificates are not actually verified by browsers

   The padlock only indicates that a certificate exists
4. 4/4A client has sent its ClientHello and received the server's flight, and finds the certificate unacceptable. What does it send next?

   Predict what happens next

   A fatal alert, and no request at all

   Its request anyway, with a warning shown to the user

   A TCP RST with no TLS message