# Question 27 2 Points Old Buddies Alice Bob Sending Messages Alice Receives Message 106 Bo Q26109509

Question 27 (2 points)

Our old buddies Alice and Bob are sending messages again. Alicereceives the message 106 from Bob, knowing n = 32283 and a = 137.Bob knows b = 233. Bob had 15716 to send. What is the correctmethod that Bob used to determine the message to send to Alice?

Question 27 options:

 (15716)^137 mod 32283 (15716)^233 mod 32283 (15716)^32283 mod 233 (15716)^32283 mod 233 (15716)^233 mod 137

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Question 28 (2 points)

Alice sends the encrypted message 168 to Bob. N=221 and a = 11.Bob knows b = 35. Using fast modular exponentiation, find themessage.

This is an Extra Credit problem and optional. You can do well onthe exam and skip this if you choose to do so.

Question 28 options:

 76 155 340 308 77

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Question 29 (2 points)

Alice sends Bob an encrypted message using the RSA encryptionmethod.

The RSA encryption method is based on two functions.

Given P = plaintext, and C = ciphertext, the two functionsare:

P = C ^ G (mod N)

C = P ^ H (mod N)

What is G?

Question 29 options:

 Bob’s private key Alice’s private key Bob’s public key Alice’s public key

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Question 30 (2 points)

Alice sends Bob an encrypted message using the RSA encryptionmethod.

The RSA encryption method is based on two functions.

Given P = plaintext, and C = ciphertext, the two functionsare:

P = C ^ G (mod N)

C = P ^ H (mod N)

What is H?

Question 30 options:

 Alice’s public key Bob’s private key Bob’s public key Alice’s private key

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Question 31 (2 points)

Which two the following are likely the prime reasons thestandard “Waterfall” model of system development has failed sooften?

Question 31 options:

 mobility and scale requirements and time to deliver stakeholders and management complexity and inherent difficulty planning and scheduling
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