(9) (Knapsack cryptosystem) Let r = (1, 3, 7, 15, 30, 61, 124). Let A = 5 and B = 253. (a) Compute the sequence where M = (M₁, M2, M3, M4, M5, M6, M7) M₁ Arį (mod B) (b) Choose the binary plaintext for i=1,2,...,7. x = (1, 0, 1, 1, 0, 1, 1) and compute the ciphertext S = x. M. (c) Compute S'A¹S (mod B) (d) Solve the subset-sum problem S' using the superincreasing sequence r.

Database System Concepts
7th Edition
ISBN:9780078022159
Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Chapter1: Introduction
Section: Chapter Questions
Problem 1PE
icon
Related questions
Question
**Knapsack Cryptosystem Example**

---

### Problem Description

Given:
- Superincreasing sequence: \( \mathbf{r} = (1, 3, 7, 15, 30, 61, 124) \).
- Constants: \( A = 5 \) and \( B = 253 \).

#### (a) Compute the Sequence

Let \( M = (M_1, M_2, M_3, M_4, M_5, M_6, M_7) \), where:
\[ M_i \equiv A r_i \ (\text{mod} \ B) \ \text{for} \ i = 1, 2, \ldots, 7. \]

#### (b) Choose the Binary Plaintext

Let the plaintext be \( x = (1, 0, 1, 1, 0, 1, 1) \).

Compute the ciphertext:
\[ S = x \cdot M. \]

#### (c) Compute Intermediate Value

Compute the intermediate value:
\[ S' = A^{-1} S \ (\text{mod} \ B). \]

#### (d) Solve the Subset-Sum Problem

Solve the subset-sum problem \( S' \) using the superincreasing sequence \( \mathbf{r} \).

---

### Explanation of Parameters and Steps

1. **Superincreasing Sequence \( \mathbf{r} \)**: This sequence is a specific type of sequence where each element is greater than the sum of all previous elements. In this case, \( \mathbf{r} = (1, 3, 7, 15, 30, 61, 124) \).

2. **Computing \( M \)**:
   \[ M_i \equiv A r_i \ (\text{mod} \ B) \]
   - Multiply each element of \( \mathbf{r} \) by \( A \) and then take modulo \( B \) to find each \( M_i \).

3. **Binary Plaintext \( x \)**: A binary vector representing the plaintext message. Each element of the vector is a bit (0 or 1).

4. **Ciphertext Calculation**:
   \[ S = x \cdot M \]
   - Compute the dot product of the plaintext vector \( x \) with the computed sequence \( M
Transcribed Image Text:**Knapsack Cryptosystem Example** --- ### Problem Description Given: - Superincreasing sequence: \( \mathbf{r} = (1, 3, 7, 15, 30, 61, 124) \). - Constants: \( A = 5 \) and \( B = 253 \). #### (a) Compute the Sequence Let \( M = (M_1, M_2, M_3, M_4, M_5, M_6, M_7) \), where: \[ M_i \equiv A r_i \ (\text{mod} \ B) \ \text{for} \ i = 1, 2, \ldots, 7. \] #### (b) Choose the Binary Plaintext Let the plaintext be \( x = (1, 0, 1, 1, 0, 1, 1) \). Compute the ciphertext: \[ S = x \cdot M. \] #### (c) Compute Intermediate Value Compute the intermediate value: \[ S' = A^{-1} S \ (\text{mod} \ B). \] #### (d) Solve the Subset-Sum Problem Solve the subset-sum problem \( S' \) using the superincreasing sequence \( \mathbf{r} \). --- ### Explanation of Parameters and Steps 1. **Superincreasing Sequence \( \mathbf{r} \)**: This sequence is a specific type of sequence where each element is greater than the sum of all previous elements. In this case, \( \mathbf{r} = (1, 3, 7, 15, 30, 61, 124) \). 2. **Computing \( M \)**: \[ M_i \equiv A r_i \ (\text{mod} \ B) \] - Multiply each element of \( \mathbf{r} \) by \( A \) and then take modulo \( B \) to find each \( M_i \). 3. **Binary Plaintext \( x \)**: A binary vector representing the plaintext message. Each element of the vector is a bit (0 or 1). 4. **Ciphertext Calculation**: \[ S = x \cdot M \] - Compute the dot product of the plaintext vector \( x \) with the computed sequence \( M
Expert Solution
steps

Step by step

Solved in 3 steps

Blurred answer
Knowledge Booster
Public key encryption
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, computer-science and related others by exploring similar questions and additional content below.
Similar questions
  • SEE MORE QUESTIONS
Recommended textbooks for you
Database System Concepts
Database System Concepts
Computer Science
ISBN:
9780078022159
Author:
Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:
McGraw-Hill Education
Starting Out with Python (4th Edition)
Starting Out with Python (4th Edition)
Computer Science
ISBN:
9780134444321
Author:
Tony Gaddis
Publisher:
PEARSON
Digital Fundamentals (11th Edition)
Digital Fundamentals (11th Edition)
Computer Science
ISBN:
9780132737968
Author:
Thomas L. Floyd
Publisher:
PEARSON
C How to Program (8th Edition)
C How to Program (8th Edition)
Computer Science
ISBN:
9780133976892
Author:
Paul J. Deitel, Harvey Deitel
Publisher:
PEARSON
Database Systems: Design, Implementation, & Manag…
Database Systems: Design, Implementation, & Manag…
Computer Science
ISBN:
9781337627900
Author:
Carlos Coronel, Steven Morris
Publisher:
Cengage Learning
Programmable Logic Controllers
Programmable Logic Controllers
Computer Science
ISBN:
9780073373843
Author:
Frank D. Petruzella
Publisher:
McGraw-Hill Education