hardope / caesar

An encryption program

Text Encryption Command-Line Tool & API

This is a command-line tool for text encryption and decryption using various algorithms. It supports multiple encryption algorithms, including Caesar cipher, ROT13, Atbash cipher, and a custom crot13 algorithm. You can use this tool to secure your text-based information or decode encrypted messages.

Table of Contents

• Supported Algorithms
• Usage Cases
• API
• Installation
  • Command Line Tool Installation
  • Web API Installation
• Usage Options
• Examples

Supported Algorithms

1. Caesar Cipher:

   • The Caesar cipher is a simple substitution cipher where each letter in the plaintext is shifted a fixed number of places down or up the alphabet.
   • For example, with a shift of 3, 'A' becomes 'D', 'B' becomes 'E', and so on.
   • In the script, the caesar_cipher function takes a text input and a shift value as parameters and returns the encrypted text.

2. ROT13 Cipher:

   • ROT13 is a special case of the Caesar cipher with a fixed shift of 13 places.
   • It's often used for obscuring text in online forums or for creating puzzles.
   • In the script, the rot13_cipher function uses the codecs.encode function with 'rot_13' encoding to perform ROT13 encryption.

3. Atbash Cipher:

   • The Atbash cipher is a substitution cipher where each letter in the plaintext is replaced with its corresponding letter in the reverse alphabet.
   • For example, 'A' becomes 'Z', 'B' becomes 'Y', and so on.
   • In the script, the atbash_cipher function takes a text input and returns the encrypted text.

4. Custom crot13 Algorithm:

   • The crot13 algorithm combines Caesar and ROT13 ciphers for encryption and decryption. When encrypting, it first applies the Caesar cipher with the specified shift value and then applies ROT13. When decrypting, it reverses the process: it first applies ROT13 and then applies the Caesar cipher with a negated shift value.

These algorithms are used for different purposes and have varying levels of security. Caesar and ROT13 ciphers are very simple and offer minimal security, while the Atbash cipher provides a bit more complexity. However, it's important to note that none of these ciphers are considered secure for modern cryptography. They are mainly used for educational and recreational purposes. For secure text encryption, it's recommended to use strong encryption algorithms like AES (Advanced Encryption Standard) provided by cryptographic libraries.

Usage Cases

• Secure Messaging: You can use this tool to encrypt sensitive text messages before sending them, ensuring that only authorized recipients can decrypt and read the messages.

• Obfuscation: The ROT13 and Atbash ciphers are often used to obfuscate text for various purposes, such as hiding spoilers or creating puzzles.

• Learning Cryptography: This tool is a practical way to learn about classic encryption algorithms like the Caesar cipher and ROT13.

API

The FastAPI Caesar Cipher API is a simple web API that provides text transformation operations using using the ciphers listed above. Additionally, it offers the ability to perform these transformations on text files and save the results to the server's "files" directory which is then served as static files made available for download.

Installation

Commmand Line Tool

To install and use the Text Encryption Command-Line Tool, follow these steps:

1. Clone the repository to your local machine:

   git clone https://github.com/hardope/caesar

2. Navigate to the project directory:

   cd tcaesar

3. Run the provided installation script to set up the environment, install dependencies, and make the command-line tool available:

   chmod +x install
   ./install

The script will take care of installing Python 3, pip, Python 3 venv, creating a virtual environment, installing the required packages from requirements.txt, and building and installing the command-line tool. It will also clean up temporary files and deactivate and delete the virtual environment when done.

Usage Options

The command-line tool provides several options to customize the encryption or decryption process:

• --help: Display help and usage info on command line

• --file: Input file to read text from.

• --text: Text to encrypt or decrypt.

• --shift: Shift value for Caesar cipher (default: 3).

• --decrypt: Flag to indicate decryption (default is encryption).

• --output: Output file to write the result to.

• --algorithm: Encryption algorithm to use (default: Caesar cipher). Supported options are 'caesar', 'rot13', 'atbash', and 'crot13'.

• --uninstall: Uninstall caesar cypher

Version

The check the installed version of caesar you have installed

caesar --version

Examples

Encrypt text using Caesar cipher:

python text_encryptor.py --text "Hello, World!" --shift 3

Decrypt text using ROT13:

python text_encryptor.py --text "Uryyb, Jbeyq!" --algorithm rot13 --decrypt

Encrypt text using the custom crot13 algorithm:

python text_encryptor.py --text "Hello, World!" --algorithm crot13 --shift 3

Decrypt text from a file and save the result to another file using ROT13:

python text_encryptor.py --file encrypted.txt --output decrypted.txt --algorithm rot13 --decrypt

Encrypt text from a file and display the result in the terminal using the Atbash cipher:

python text_encryptor.py --file input.txt --algorithm atbash

Encrypt text from a file and display the result in the terminal using the custom crot13 algorithm:

python text_encryptor.py --file input.txt --algorithm crot13 --shift 3

Decrypt text from a file and display the result in the terminal using the custom crot13 algorithm:

python text_encryptor.py --file encrypted.txt --algorithm crot13 --decrypt --shift 3

Encrypt text from a file and save the result to another file using Caesar cipher:

python text_encryptor.py --file input.txt --output encrypted.txt --shift 5

Decrypt text from a file and save the result to another file using ROT13:

python text_encryptor.py --file encrypted.txt --output decrypted.txt --algorithm rot13 --decrypt

Encrypt text from a file and display the result in the terminal using the Atbash cipher:

python text_encryptor.py --file input.txt --algorithm atbash

Encrypt text from a file and display the result in the terminal using the custom crot13 algorithm:

python text_encryptor.py --file input.txt --algorithm crot13 --shift 3

Decrypt text from a file and display the result in the terminal using the custom crot13 algorithm:

python text_encryptor.py --file encrypted.txt --algorithm crot13 --decrypt --shift 3

These examples demonstrate how to use the Text Encryption Command-Line Tool with file inputs and outputs, allowing you to perform encryption and decryption on text stored in files.

WEB API

To run the FastAPI application locally, follow these steps:

• Clone the repository

git clone https://github.com/hardope/caesar

• Navigate to the project directory

cd caesar

• Create a virtual environment

python3 -m venv venv

• Activate virtual environment

source venv/bin/activate

• Install the required dependencies using pip

pip install -r requirements.txt

• Start the web server

uvicorn app:app