secure-sym-encryption.js

const crypto = require("crypto");

const key = crypto.randomBytes(32);
const nonce = crypto.randomBytes(12);
const opts = { authTagLength: 16 };

const cipher = crypto.createCipheriv("chacha20-poly1305", key, nonce, opts);

const plaintext = "Hello World, il se fait tard ce soir.";

const aad = crypto.randomBytes(5);
cipher.setAAD(aad, { plaintextLength: Buffer.byteLength(plaintext) });
const ciphertext = cipher.update(plaintext, "utf8");
cipher.final();
const tag = cipher.getAuthTag();

// Now transmit { ciphertext, nonce, tag }.
console.log(ciphertext, nonce, tag);

const decipher = crypto.createDecipheriv("chacha20-poly1305", key, nonce, opts);
decipher.setAuthTag(tag);
decipher.setAAD(aad, { plaintextLength: ciphertext.length });

const receivedPlaintext = decipher.update(ciphertext, null, "utf8");
console.log(receivedPlaintext);

try {
  decipher.final();
} catch (err) {
  console.error("Authentication failed!");
  return;
}