Question 9: A Cryptosystem is designed to double encrypt the plaintext for better usage. Any plaintext is first encrypted with Playfair Cipher then output of Playfair cipher is encrypted with Vigenere cipher. A Cipher generated using this cryptosystem is given below. Key used in both encryptions is "Message". (10) Cipher= ABCDEFGHUKLMN Answer: Question 10: You are given the following informal firewall policy" details to be implemented using a firewall (10) E-mail may be sent using SMTP in both directions through the firewall. Users outside may retrieve their e-mail Web requests (both insecure and secure) are allowed from any internal user out through the firewall. Web requests (both insecure and secure) are allowed from anywhere on the Internet to the DMZ Web server. External DNS requests are provided by the DMZ DNS server. SNMP management requests are permitted from the internal management hosts to the firewalls Design suitable packet filter rulesets to be implemented on the "Packet Level Firewall "to satisfy the aforementioned policy requirements