Java Command-Line File Encryptor

A simple, robust command-line utility built in Java to perform file encryption and decryption using the AES algorithm. This tool can securely encrypt any type of file (text, images, PDFs, etc.) and is built and packaged using Apache Maven.

Features

• Strong Encryption: Uses AES-128, a symmetric-key algorithm that is an industry standard.
• File Agnostic: Encrypts and decrypts any file type by handling data at the byte level.
• Command-Line Interface: Easy to use and scriptable, with clear arguments for mode, key, and files.
• Standalone Application: Packaged by Maven into a single, runnable JAR file.
• Robust Error Handling: Includes custom exceptions to manage cryptographic and file I/O errors gracefully.

Prerequisites

To build and run this project, you will need:

• Java Development Kit (JDK) 8 or higher
• Apache Maven

How to Build

1. Clone the repository:

   git clone [https://github.com/your-username/java-file-encryptor.git](https://github.com/your-username/java-file-encryptor.git)

2. Navigate to the project directory:

   cd java-file-encryptor

3. Build the project and package it into a runnable JAR:

   mvn clean package

   The JAR file will be created in the target/ directory.

How to Use

The application is run from the terminal with the following command structure:

java -jar target/file-encryptor-1.0-SNAPSHOT.jar <mode> <key> <inputFile> <outputFile>

• <mode>: encrypt or decrypt.
• <key>: A secret key that must be exactly 16 characters long.
• <inputFile>: The path to the file you want to process.
• <outputFile>: The path where the resulting file will be saved.

Example Usage

1. Encrypting a Text File

java -jar target/file-encryptor-1.0-SNAPSHOT.jar encrypt "ThisIsA16CharKey" message.txt secret.data

This will encrypt message.txt and save the result as secret.data.

2. Decrypting a Text File

java -jar target/file-encryptor-1.0-SNAPSHOT.jar decrypt "ThisIsA16CharKey" secret.data revealed.txt

This will decrypt secret.data using the same key and save the result as revealed.txt.

3. Encrypting an Image

java -jar target/file-encryptor-1.0-SNAPSHOT.jar encrypt "Another16CharKey" photo.jpg encrypted.img

This demonstrates that the tool works on binary files like images as well.

🛡️ Security Note

This project is for educational purposes to demonstrate Java's cryptographic capabilities and file handling. Passing a secret key directly as a command-line argument is insecure in a production environment, as it can be exposed in your shell history. In a real-world application, keys should be managed through more secure mechanisms.