414-e1-F08 - CMSC 414 F08 Exam 1 Page 1 of 9 Name:_ _ Total...

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CMSC 414 F08 Exam 1 Page 1 of 9 Name:____________________________________ ____________________________________________________________________________________________________ Total points: 71. Total time: 75 minutes. 9 problems over 9 pages. No book, notes, or calculator 1. [14 points] a. Are n=221 and e=3 valid numbers for RSA. Explain. If you answer yes, obtain the corresponding d. b. Are n=221 and e=5 valid numbers for RSA. Explain. If you answer yes, obtain the corresponding d.
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CMSC 414 F08 Exam 1 Page 2 of 9 Name:____________________________________ 2. [6 points] Sensor X periodically sends a 32-octet measurement to a receiver Y (1 octet = 8 bits). One day the administrator decides that X should protect the measurement data by adding a MAC obtained using DES in CBC mode (in the standard way). How many octets does X now send for each measurement? Explain your answer.
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CMSC 414 F08 Exam 1 Page 3 of 9 Name:____________________________________ 3. [10 points] An organization wants you to implement a PKI (public key infrastructure) for its employees. It has a large number of employees, divided into class-A employees and class-B employees. Class-A employees stay with the organization for several years on an average. When a class-A employee leaves, his/her access privileges must be revoked within an hour. Class-B employess stay with the organization for either six or seven days. When a class-B employee leaves, his/her access privileges must be revoked within a day. Identify the documents of the PKI (e.g., certificates) and their structure (e.g., fields). Impose constraints, if any, that would improve performance by exploiting the nature of the employees.
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CMSC 414 F08 Exam 1 Page 4 of 9 Name:____________________________________ 4. [15 points] client A (has J) server B (has J) generate random N A
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This note was uploaded on 03/22/2012 for the course CSE 5345 taught by Professor Youngheliu during the Spring '12 term at UT Arlington.

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414-e1-F08 - CMSC 414 F08 Exam 1 Page 1 of 9 Name:_ _ Total...

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