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a.  Intrusion detection is based on the assumption that the behavior of the intruder differs from that of a legitimate user in ways that can be quantified. Of course, we cannot expect that there will be a crisp, exact distinction between an attack by an intruder and the normal use of resources by an authorized user. This poses a challenge to the use of IDS. Briefly discus the challenges and propose a cure.

b.  Blockchain is a breakthrough technology that is expected to alter most industries in the coming years and it particularly touted so because of confidentiality, authentication and integrity that it offers which makes it independent, transparent and secure. Experts says that these important principles of security are achievable because blockchains employs hash functions and public key encryption. Briefly discuss how these cryptographic techniques offer confidentiality, authentication and integrity that gives blockchain its security.

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a.  As a user, you may have come across systems with antivirus installed on them yet the same computer gets infected with malwares. Briefly explains this phenomenon to a lay person.                     

b.  Suppose that Bob wants to send a message to Alice. Bob does not want the message be kept secret; however, he wants Alice to be able to ascertain that the message is indeed from him. Briefly explain what Bob can do to help Alice ascertain if it’s indeed coming from him and whether the message has not been altered.                

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a.  One of the challenges to computer Security is that it’s often an afterthought to be incorporated into a system after the design is complete rather than being an integral part of the design process. Brief Discuss the security implication if it’s an afterthought.     

b.   As a newly employed system administrator in an IT firm, you observed that the firm has no security policy on Bring your own device and Incidence response.

i. Explain the term Security policy to your boss bring to bear the need for it.

ii. Briefly formulate four security policies each for bring your own device and virus infections incidence

Consider a set up that corresponds between alphabetic characters as follows

Assuming the encryption algorithm is C=11m+7 mod 26, where m is the message and C is the ciphertext.

I.	Encrypt the word “CYBERCRIME”
II.	Derive the decryption algorithm.

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