We discussed examples in class on using public key crypto to achieve confidentiality and integrity. Let's look at a case where Alice wants to send a message to Bob securely. Alice wants to keep the confidentiality and integrity of the message: Alice first encrypts the message M using Bob's public key, i.e. {M}Bob. Then, Alice signs on this encrypted message using her private key, i.e. [{M}Bob] Alice. After signing, Alice sends it to the network. Now a third person, Charlie, intercepts what Alice has sent out. Please answer each of the following questions succinctly and to the point. 1. How can Charlie verify Alice's signature? 2. After verifying, can Charlie recover the content of the message M? Why or why not? 3. Now Charlie got the encrypted message {M} Bob, can he make Bob believe that he (Charlie) is the owner of this message? If so, how?