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Unformatted text preview: CS70, Midterm 2, Spring 2002 file:///C:/Documents%20and%20Settings/Jason%20Raftery/Desktop/R... 1 of 2 5/12/2006 8:45 PM CS70, Spring 2002 Midterm 2 Vazirani Problem 1. (Each 5 pts.) Short questions (a) Find gcd(3n+2, 2n + 1), where n is a positive integer. (b) For your RSA public key must use N = p · q = 55, and an exponent e which is either 5 or 9. Which of 5 or 9 should be your public exponent? Why? (c) Suppose you use a polynomial p(x) of degree 5 over the field GF 13 as your errorcorrecting code (to encode the message p (0)). You happen to know that you correctly received the values p (1), p (2), p (3), p (10), p (11), but all the remaining values were corrupted during transmission. Can you recover the message p (0)? How? (d) Find a pair of integers x and y such that 21 x +54 y = 1, or prove that no such pair exists. (e) Compute 2 110001 11 1100001 (mod 23). Problem 2. (25 pts.) RSA Joe Hacker decides that he wants to have two publicprivate key pairs to be used with RSA  that way...
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This note was uploaded on 09/26/2009 for the course CS 70 taught by Professor Papadimitrou during the Fall '08 term at Berkeley.
 Fall '08
 PAPADIMITROU
 Computer Science

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