Information Systems Security

Project Description

This repository contains exercises and explanations of ciphers and algorithms studied in the Information Systems Security course at DIEEI, University of Catania. The project includes implementations of various encryption algorithms, which will be continuously expanded and improved with the addition of new methods and ciphers.

Exercises and Input

The exercises in this repository require input consisting of:

• A plaintext.txt file in the input folder, containing the plaintext to be encrypted or decrypted.
• A keys.txt file in the same folder, containing one or more encryption keys, each on a separate line.

Note: Some algorithms, such as the Caesar cipher, require each key to be an integer. If a key is invalid, an error will be displayed.

How to Run the Project

1. Clone the repository:

   git clone [email protected]:Teosche/information-systems-security.git

2. Navigate to the directory of the algorithm you're interested in:

   cd <algorithm_directory>

3. Run the desired module:

   python3 -m <cipher_name>.<filename>

   Examples:

   From mono_chipers directory:

   • To run the Caesar cipher:

     python3 -m caesar.caesar

   • To run the Playfair cipher:

     python3 -m playfair.playfair

Execution Example

To encrypt or decrypt a text:

1. Ensure the input directory contains the plaintext.txt and keys.txt files.
2. If they do not already exist, the cipher and decrypt directories will be automatically created to store results.
3. Start the desired algorithm.

Implemented Ciphers

Monoalphabetic Ciphers

• Caesar: The Caesar cipher shifts each letter in the plaintext by a fixed number of positions in the alphabet, determined by the key. For example, with a key of 3, A becomes D, B becomes E, and so on.

• Playfair: The Playfair cipher uses a 5x5 matrix to encrypt pairs of letters. Each letter pair is substituted based on its position in the matrix. If a pair consists of two identical letters, a separator is inserted.

Technology Stack

The scripts are written in Python.

Contributions

The repository is continuously evolving. Contributions for implementing new algorithms or improvements are welcome. Feel free to open a pull request or create an issue to report problems or suggestions.

License

This project is distributed under the MIT license.