What are the essential ingredients of a symmetric cipher?

  • 2.1 What are the essential ingredients of a symmetric cipher?
  • 2.2 What are the two basic functions used in encryption algorithms?
  • 2.3 How many keys are required for two people to communicate via a symmetric cipher?
  • 2.4 What is the difference between a block cipher and a stream cipher?
  • 2.5 What are the two general approaches to attacking a cipher?
  • 2.6 Why do some block cipher modes of operation only use encryption while others use both encryption and decryption?
  • 2.7 What is triple encryption?
  • 2.8 Why is the middle portion of 3DES a decryption rather than an encryption?

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In no less than 250 words, explain the difference between symmetric and asymmetric encryption.  Which one is better and why?

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Any data that is sensitive or critical for business or military purposes should be encrypted. But what does it mean to be encrypted. What does encrypted data look like? In this lab we will look at data which is unencrypted and data that is encrypted. We will use a tool called GNS3 to simulate two routers that are connected via a point-to-point link. We will run data through this link while looking at the packets going through it. The tool we will use to view the data is Wireshark which is probably the most important tool we as network engineers have in our toolbelt. Let’s answer the following questions as we go through the lab.

Ÿ 1. What is the cleartext data that is being sent in the ping between the two PCs? _____________________

Ÿ 2. What is the protocol used for the ping utility? ____________________

Ÿ 3. How many ping messages do you see? _____________________ Why? ________________________________________________________________________

Ÿ 4. Is this data encrypted or unencrypted? _____________________________

Ÿ 5. Now let’s make a change in the router. What types of messages do you see now? Does it look the same as the messages we saw before we made the change to the router? ________________________

Ÿ 6. What protocol do you see now? ____________________

Ÿ 7. Are you still able to see the source and destination MAC address? __________What layer is this you are looking at the MAC address in? _____________

Ÿ 8. Are you still able to see the source and destination IP address? __________What layer is this you are looking at the IP address in? _____________

Ÿ 9. Can you see the cleartext data you saw before? ____________________________

Ÿ 10. Explain the ESP protocol. Does what we see in Wireshark make sense? Write a paragraph answering these two questions.