Encrypting files with NodeJS

encryption.js

const crypto = require('crypto');
const algorithm = 'aes-256-ctr';
let key = 'MySuperSecretKey';
key = crypto.createHash('sha256').update(String(key)).digest('base64').substr(0, 32);

const encrypt = (buffer) => {
    // Create an initialization vector
    const iv = crypto.randomBytes(16);
    // Create a new cipher using the algorithm, key, and iv
    const cipher = crypto.createCipheriv(algorithm, key, iv);
    // Create the new (encrypted) buffer
    const result = Buffer.concat([iv, cipher.update(buffer), cipher.final()]);
    return result;
};

const decrypt = (encrypted) => {
   // Get the iv: the first 16 bytes
   const iv = encrypted.slice(0, 16);
   // Get the rest
   encrypted = encrypted.slice(16);
   // Create a decipher
   const decipher = crypto.createDecipheriv(algorithm, key, iv);
   // Actually decrypt it
   const result = Buffer.concat([decipher.update(encrypted), decipher.final()]);
   return result;
};

const plain = Buffer.from('Hello world');

const encrypted = encrypt(plain);
console.log('Encrypted:', encrypted.toString());

const decrypted = decrypt(encrypted);
console.log('Decrypted:', decrypted.toString());