Answered step by step
Verified Expert Solution
Link Copied!

Question

1 Approved Answer

Suppose that n = pq is an RSA modulus (i e, p and q are distinct odd primes), and let alpha epsilon Z_n*. For a

image text in transcribed

Suppose that n = pq is an RSA modulus (i e, p and q are distinct odd primes), and let alpha epsilon Z_n*. For a positive int eger m and for any alpha epsilon Z_m*, define ord_m (alpha) to be the order of alpha in the group Z_m*. (a) Prove that ord_n (alpha) = lcm (ord_p (alpha), ord_q (alpha)). (b) Suppose that gcd(p - 1, q - 1) = d. Show that there exists an element alpha epsilon Z_n* such that ord_n (alpha) = phi (n)/d. c) Suppose that gcd(p - 1, q - 1) = 2, and we have an oracle that solves the Discrete Logarithm problem in the subgroup (alpha), where alpha epsilon Z_n* has order phi (n)/2. That is, given any beta epsilon (alpha), the oracle will find the discrete logarithm alpha = log_alpha beta, where 0 lessthanorequalto a lessthanorequalto phi (n)/2 - 1.(The value phi(n)/2 is secret however.) Suppose we compute the value beta = alpha^n mod n and then we use the oracle to find alpha = log_alpha beta. Assuming that p > 3 and q > 3, prove that n - a = phi (n). (d) Describe how n can easily be factored, given the discrete logarithm a = log_alpha beta from (c). Suppose that n = pq is an RSA modulus (i e, p and q are distinct odd primes), and let alpha epsilon Z_n*. For a positive int eger m and for any alpha epsilon Z_m*, define ord_m (alpha) to be the order of alpha in the group Z_m*. (a) Prove that ord_n (alpha) = lcm (ord_p (alpha), ord_q (alpha)). (b) Suppose that gcd(p - 1, q - 1) = d. Show that there exists an element alpha epsilon Z_n* such that ord_n (alpha) = phi (n)/d. c) Suppose that gcd(p - 1, q - 1) = 2, and we have an oracle that solves the Discrete Logarithm problem in the subgroup (alpha), where alpha epsilon Z_n* has order phi (n)/2. That is, given any beta epsilon (alpha), the oracle will find the discrete logarithm alpha = log_alpha beta, where 0 lessthanorequalto a lessthanorequalto phi (n)/2 - 1.(The value phi(n)/2 is secret however.) Suppose we compute the value beta = alpha^n mod n and then we use the oracle to find alpha = log_alpha beta. Assuming that p > 3 and q > 3, prove that n - a = phi (n). (d) Describe how n can easily be factored, given the discrete logarithm a = log_alpha beta from (c)

Step by Step Solution

There are 3 Steps involved in it

Step: 1

blur-text-image

Get Instant Access to Expert-Tailored Solutions

See step-by-step solutions with expert insights and AI powered tools for academic success

Step: 2

blur-text-image

Step: 3

blur-text-image

Ace Your Homework with AI

Get the answers you need in no time with our AI-driven, step-by-step assistance

Get Started

Recommended Textbook for

Database Design Application And Administration

Authors: Michael Mannino, Michael V. Mannino

2nd Edition

0072880678, 9780072880670

More Books

Students also viewed these Databases questions

Question

In an Excel Pivot Table, how is a Fact/Measure Column repeated?

Answered: 1 week ago