/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 12 Find the sequence of pseudorando... [FREE SOLUTION] | 91Ó°ÊÓ

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Find the sequence of pseudorandom numbers generated by the power generator with \(p=11, d=2,\) and seed \(x_{0}=3 .\)

Short Answer

Expert verified
The sequence is 3, 9, 4, 5 and then it repeats.

Step by step solution

01

Understand the Formula

The power generator formula is given by: \[ x_{n+1} = (x_n)^d \bmod p \] where \(p\) is a prime number, \(d\) is a fixed exponent, and \(x_0\) is the initial seed.
02

Initialize the Seed

The initial seed \(x_0\) is given as 3. This will be the starting point of the sequence.
03

Calculate First Term \(x_1\)

Using the formula and the given values: \[ x_1 = (x_0)^d \bmod p \] Substitute \(x_0 = 3\), \(d = 2\), and \(p = 11\): \[ x_1 = 3^2 \bmod 11 \] Calculate the exponentiation first: \[ 3^2 = 9 \] Then apply the modulo operation: \[ 9 \bmod 11 = 9 \] So, \(x_1\) is 9.
04

Calculate Second Term \(x_2\)

Using the previous result \(x_1 = 9\): \[ x_2 = (x_1)^d \bmod p \] Substitute \(x_1 = 9\), \(d = 2\), and \(p = 11\): \[ x_2 = 9^2 \bmod 11 \] Calculate the exponentiation first: \[ 9^2 = 81 \] Then apply the modulo operation: \[ 81 \bmod 11 = 4 \] So, \(x_2\) is 4.
05

Calculate Third Term \(x_3\)

Using the previous result \(x_2 = 4\): \[ x_3 = (x_2)^d \bmod p \] Substitute \(x_2 = 4\), \(d = 2\), and \(p = 11\): \[ x_3 = 4^2 \bmod 11 \] Calculate the exponentiation first: \[ 4^2 = 16 \] Then apply the modulo operation: \[ 16 \bmod 11 = 5 \] So, \(x_3\) is 5.
06

Calculate Fourth Term \(x_4\)

Using the previous result \(x_3 = 5\): \[ x_4 = (x_3)^d \bmod p \] Substitute \(x_3 = 5\), \(d = 2\), and \(p = 11\): \[ x_4 = 5^2 \bmod 11 \] Calculate the exponentiation first: \[ 5^2 = 25 \] Then apply the modulo operation: \[ 25 \bmod 11 = 3 \] So, \(x_4\) is 3. Notice that this is the same as the initial seed, indicating a repeating cycle.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Power Generator
A power generator is a type of pseudo-random number generator that uses a mathematical formula to produce a sequence of numbers. The power generator used here follows the formula: \[ x_{n+1} = (x_n)^d \bmod p \]. In this formula:
  • \( x_n \) is the current term in the sequence.
  • \( d \) is a constant exponent.
  • \( p \) is a prime number used in the modulo operation.
This method relies on high powers and modulo operations to generate the next number in the sequence, ensuring a pattern that is complex and hard to predict.
Modulo Operation
The modulo operation is a fundamental concept in digital algorithms and discrete mathematics. It performs division of one number by another and returns the remainder. In our power generator formula, it is used to keep the values within a bounded range determined by the prime number \( p \).

For example, when we calculate \( 9 \bmod 11 \), we divide 9 by 11, which gives us a quotient of 0 and a remainder of 9. Therefore, \( 9 \bmod 11 = 9 \). Applying modulo operation repeatedly ensures that our sequence remains within the set {0, 1, 2, ..., p-1}, maintaining consistency and periodicity.
Seed Value
The seed value is the initial starting point of the sequence in a pseudo-random number generator. It plays a crucial role because the entire number sequence is generated based on this initial value.

In our example, the seed value is \( x_0 = 3 \) . From this value, we use the power generator formula: \[ x_{n+1} = (x_n)^d \bmod p \] to calculate the subsequent terms. A different seed value would produce a completely different sequence, highlighting the importance of the initial seed in determining the path of the pseudo-random sequence.
Sequence Calculation
Sequence calculation in the context of our power generator involves using the given formula to find each term successively. Starting from the seed, each new term is derived by raising the current term to the power of \( d \) and then applying the modulo operation with \( p \). Here’s a brief breakdown:
  • Start: \( x_0 = 3 \)
  • First term: \( x_1 = (x_0)^d \bmod p = 9 \)
  • Second term: \( x_2 = (x_1)^d \bmod p = 4 \)
  • Third term: \( x_3 = (x_2)^d \bmod p = 5 \)
  • Fourth term: \( x_4 = (x_3)^d \bmod p = 3 \)
Notice that \( x_4 \) returns to the seed value, indicating a repeating cycle. This shows how sequence calculation can reveal periodic patterns in pseudo-random number generation.
Discrete Mathematics
Discrete mathematics is the study of mathematical structures that are fundamentally countable or discrete rather than continuous. It provides the theoretical underpinnings for many algorithms, including pseudo-random number generation. Concepts from discrete mathematics, such as modulo operations, sequences, and prime numbers, are crucial for understanding how generators like our power generator work.

Unlike continuous mathematics, which deals with smooth and infinite structures, discrete mathematics focuses on distinct values, making it ideal for computer algorithms that work with finite sets and integers. Understanding the discrete nature of numbers and operations helps us grasp the mechanics behind the pseudo-random number generator, ensuring accurate implementation and analysis.

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Most popular questions from this chapter

In Exercises \(24-27\) first express your answers without com- puting modular exponentiations. Then use a computational aid to complete these computations. What is the original message encrypted using the RSA system with \(n=43 \cdot 59\) and \(e=13\) if the encrypted message is 066719470671\(?\) (To decrypt, first find the decryption exponent \(d\) which is the inverse of \(e=13\) modulo \(42 \cdot 58 .\)

Prove that for every positive integer \(n,\) there are \(n\) consecutive composite integers. [Hint: Consider the \(n\) consecutive integers starting with \((n+1) !+2 . ]\)

The Vigenère cipher is a block cipher, with a key that is a string of letters with numerical equivalents \(k_{1} k_{2} \ldots k_{m},\) where \(k_{i} \in \mathbf{Z}_{26}\) for \(i=1,2, \ldots, m .\) Suppose that the numerical equivalents of the letters of a plaintext block are \(p_{1} p_{2} \ldots p_{m} .\) The corresponding numerical ciphertext block is \(\left(p_{1}+k_{1}\right)\) mod 26 \(\left(p_{2}+k_{2}\right) \bmod 26 \ldots\left(p_{m}+k_{m}\right)\) mod \(26 .\) Finally, we translate back to letters. For example, suppose that the key string is RED, with numerical equivalents \(1743 .\) Then, the plaintext ORANGE, with numerical equivalents \(141700130604,\) is encrypted by first splitting it into two blocks 141700 and 13 \(0604 .\) Then, in each block we shift the first letter by 17 , the second by \(4,\) and the third by \(3 .\) We obtain 52103 and 0410 \(07 .\) The cipherext is FVDEKH. Use the Vigenère cipher with key BLUE to encrypt the message SNOWFALL.

Determine whether the integers in each of these sets are pair wise relatively prime. $$\begin{array}{ll}{\text { a) } 11,15,19} & {\text { b) } 14,15,21} \\\ {\text { c) } 12,17,31,37} & {\text { d) } 7,8,9,11}\end{array}$$

Use the extended Euclidean algorithm to express \(\operatorname{gcd}(252,356)\) as a linear combination of 252 and \(356 .\)

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