encrypt-decrypt-file.js

const fs = require('fs');
const crypto = require('crypto');

// Encryption settings
const algorithm = 'aes-256-cbc'; // Algorithm to use
const iterations = 100000; // Number of iterations for PBKDF2
const keyLength = 32; // Key length for AES-256
const ivLength = 16; // IV length for AES

// Function to derive a key and IV from a passphrase and salt
function deriveKeyAndIV(password, salt) {
  // Derive the key using PBKDF2
  const key = crypto.pbkdf2Sync(password, salt, iterations, keyLength, 'sha256');
  const iv = key.subarray(0, ivLength); // Use the first 16 bytes as the IV
  return { key, iv };
}

// Function to encrypt the file content
function encryptFile(filePath, password) {
  try {
    // Generate a random salt
    const salt = crypto.randomBytes(16);

    // Derive the key and IV from the passphrase and salt
    const { key, iv } = deriveKeyAndIV(password, salt);

    // Read the file data
    const fileData = fs.readFileSync(filePath);
    console.log(fileData)

    // Create cipher
    const cipher = crypto.createCipheriv(algorithm, key, iv);
    // Encrypt the data
    const encryptedData = Buffer.concat([cipher.update(fileData), cipher.final()]);
    // console.log(encryptedData)

    // Write the salt and encrypted data back to the file
    fs.writeFileSync(filePath, Buffer.concat([salt, encryptedData]));

    console.log('File encrypted successfully.');
  } catch (error) {
    console.error('Error during encryption:', error.message);
  }
}

// Function to decrypt the file content
function decryptFile(filePath, password) {
  try {
    // Read the file data
    const fileData = fs.readFileSync(filePath);
    console.log(fileData)

    // Extract the salt (first 16 bytes) and the encrypted data
    const salt = fileData.subarray(0, 16);
    const encryptedData = fileData.subarray(16);

    // Derive the key and IV from the passphrase and extracted salt
    const { key, iv } = deriveKeyAndIV(password, salt);

    // Create decipher
    const decipher = crypto.createDecipheriv(algorithm, key, iv);

    // Decrypt the data
    const decryptedData = Buffer.concat([decipher.update(encryptedData), decipher.final()]);
    // console.log(decryptedData)

    // Write the decrypted data back to the file
    fs.writeFileSync(filePath, decryptedData);

    console.log('File decrypted successfully.');
  } catch (error) {
    console.error('Error during decryption:', error.message);
  }
}

// Example usage
const filePath = './image.jpeg'; // Replace with your file path
const password = 'this is my encryption password'; // Replace with your passphrase

// Encrypt the file
// encryptFile(filePath, password);

// Decrypt the file (to verify)
// decryptFile(filePath, password);