1. What are ping and traceroute? How does each work? Ping is the speed of your Internet connection. Traceroute records the route from your computer to other computers through the Internet.
2. What are the benefits of packet switching? Packet switching makes the files smaller by breaking up one document into smaller segments of the document and sending them out in different routes, thus it is quicker and more efficient.
3. What is the TCP/IP Model? The TCP/IP Model is the basic communication protocol of the Internet. It goes from the levels of application, transport, Internet and network interface.
4. What are packet sniffers? Why is it important to protect your data when using public wifi connections? Packet sniffers target packets of data over the Internet. When using public WiFi, it is easy for hackers to get your IP address and see what you are doing on the public WiFi.
5. What is the difference between IPv4 and IPv6? Why have we shifted to IPv6? IPv4 is the version of the Internet Protocol that provides unique IP addresses consisting of a 32 bit number using decimal notation, having over 4 billion different IP addresses. IPv6 is the version of the Internet Protocol that provides unique IP addresses consisting of a 128 bit number in hexadecimal notation, having over 320 undecillion different IP addresses. This provides many IP addresses and little to no fear of running out of IP addresses.
6. What is the link between IP addresses and domain names? An IP address is an address given to a computer to identify it on a network. A DNS address is a Domain Name Service which translates a domain name into IP addresses.
7.6 Cryptography Basics Reflections
1. Explain briefly how the following substitution ciphers can be broken: Caesar cipher, Simple substitution cipher, Vigenere cipher. The Caesar cipher can be broken by a brute force attack with a maximum of only 25 attempts. The Caesar cipher only shifts the alphabet so it can only shift over 25 characters before just repeating. A simple substitution cipher can be figured out through brute force which would take at most 26! attempts or with frequency analysis. It is 26! attempts because "a" is replaced by one of 26 letters, "b" is replaced by one of 25 remaining letters, etc. Vigenere cipher is broken through frequency analysis.
2. Define symmetric encryption. Symmetric encryption uses the same key for encrypting plaintext as it does for decrypting ciphertext.
7.7 Cryptography: Securing the Internet Reflections
1. Explain in your own words how public key encryption is not symmetric. Public key encryption is not symmetric because the public key can encrypt any message but only the person with a complementary private key can decrypt the message. The keys are not the same thus they are asymmetric.
2. Cryptography relies on open standards - protocols or standards that are publicly available. Diffie-Hellman and RSA are all open cryptographic standards. Why is it necessary to use open standards in cryptography? (Hint: consider the need for public keys) Open standards are necessary because they make public key exchanges possible. They are the protocols and algorithms that allow for people to share parts of the key publicly while still allowing them to safely keep their full key very protected.