The computers on two networks need to securely communicate and they use two gateways. Each gateway stores its private and public keys as well as the public key of the other gateway. They encrypt the message on one gateway and decrypted on the other. The computers on each network do not store these keys, but they use the keys that they have stored, as in part A, to encrypt their messages before sending them to the gateways. a) Sketch how does the message look like when it leaves the computer and when it leaves the gateway. What information can be encrypted and what information should be available in unencrypted format. Why? Note: The message has a payload and a header (m = hp). The header contains sender’s and receiver’s address, while the payload contains data. Use SC for sending computer, RC for receiving computer, SG for sending gateway, RG for receiving gateway, KPu for public key, KPr for private key. For example, KPuSCN1 is the public key for sending computer on network 1. Also, {m}KPuSCN2 is message encrypted with public key of sending computer on network 2. b) Would this protocol decrease the number of public and private keys needed in part A? Explain. Show how many keys are needed to be stored per computer.