2. A typical request from a web browser to a web server uses both public and private key cryptography. A typical exchange begins with a series of short messages that are encrypted with public-key cryptography, then a symmetric key is established and the remainder of the session's communications are secured with private-key cryptography. A. Without knowing any of the details of this transaction, why do you expect that the exchange begins with public-key cryptography? Give one reason. (5 pts) B. Suggest one reason that communications switch from public-key to private-key cryptography (i.e., why not simply keep using public-key encryption?) (5 pts)