Assignment 2

 

• 2.1 What are the essential ingredients of a symmetric cipher? 40 - 45 words is enough.
• 2.2 What are the two basic functions used in encryption algorithms? 40 - 45 words is enough.
• 2.3 How many keys are required for two people to communicate via a symmetric cipher? 40 - 45 words is enough.
• 2.4 What is the difference between a block cipher and a stream cipher? 40 - 45 words is enough.
• 2.5 What are the two general approaches to attacking a cipher? 40 - 45 words is enough.
• 2.6 Why do some block cipher modes of operation only use encryption while others use both encryption and decryption? 40 - 45 words is enough.
• 2.7 What is triple encryption? 40 - 45 words is enough.
• 2.8 Why is the middle portion of 3DES a decryption rather than an encryption? 40 - 45 words is enough.
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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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