I need to encrypt a chat message that will be stored a database. The data is a string of characters of various lengths. I want to use the native node.js crypto library and use a symmetric encryption protocol such as AES 256. I have concerns are the following:
- Is CBC the correct AES mode for this use case for this type of field stored in a
TEXTfield in MySQL? - Does the key look like it is generated correctly?
- Is the IV correct? Is prepending the IV to the encrypted text a proper way to do it or should it be a separate field?
// AES RFC - https://tools.ietf.org/html/rfc3602
const crypto = require('crypto');
const algorithm = 'aes-256-cbc';
// generate key with crypto.randomBytes(256/8).toString('hex')
const key = '6d858102402dbbeb0f9bb711e3d13a1229684792db4940db0d0e71c08ca602e1';
const IV_LENGTH = 16;
const encrypt = (text) => {
const iv = crypto.randomBytes(IV_LENGTH);
const cipher = crypto.createCipheriv(algorithm, Buffer.from(key, 'hex'), iv);
let encrypted = cipher.update(text);
encrypted = Buffer.concat([encrypted, cipher.final()]);
return `${iv.toString('hex')}:${encrypted.toString('hex')}`;
};
const decrypt = (text) => {
const [iv, encryptedText] = text.split(':').map(part => Buffer.from(part, 'hex'));
const decipher = crypto.createDecipheriv(algorithm, Buffer.from(key, 'hex'), iv);
let decrypted = decipher.update(encryptedText);
decrypted = Buffer.concat([decrypted, decipher.final()]);
return decrypted.toString();
};
exports.encrypt = encrypt;
exports.decrypt = decrypt;