FileEncryptorDecryptor.java

import java.io.*;
import java.util.Scanner;

public class FileEncryptorDecryptor {
    private static final int SHIFT_KEY = 3; // Simple Caesar cipher shift

    public static void encryptFile(String inputFile, String outputFile) throws IOException {
        processFile(inputFile, outputFile, SHIFT_KEY);
    }

    public static void decryptFile(String inputFile, String outputFile) throws IOException {
        processFile(inputFile, outputFile, -SHIFT_KEY);
    }

    private static void processFile(String inputFile, String outputFile, int shift) throws IOException {
        try (BufferedReader reader = new BufferedReader(new FileReader(inputFile));
             BufferedWriter writer = new BufferedWriter(new FileWriter(outputFile))) {
            
            int character;
            while ((character = reader.read()) != -1) {
                writer.write(character + shift);
            }
        }
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        
        System.out.print("Enter the file path: ");
        String inputFile = scanner.nextLine();
        
        System.out.print("Enter output file path: ");
        String outputFile = scanner.nextLine();
        
        System.out.print("Do you want to encrypt or decrypt? (e/d): ");
        char choice = scanner.next().charAt(0);
        
        try {
            if (choice == 'e') {
                encryptFile(inputFile, outputFile);
                System.out.println("File encrypted successfully.");
            } else if (choice == 'd') {
                decryptFile(inputFile, outputFile);
                System.out.println("File decrypted successfully.");
            } else {
                System.out.println("Invalid choice. Please enter 'e' for encryption or 'd' for decryption.");
            }
        } catch (IOException e) {
            System.out.println("Error processing file: " + e.getMessage());
        }
        
        scanner.close();
    }
}