Java String Encryption with key generation using Nodes native "Crypto" Library

/**
 * An example for synchronous encryption and decryption of a String featuring:
 * - An out of the box working Example
 * - Generation of a random Key
 * - Utf8 Encoding of Strings
 * - Base64 String encoding of byte-Arrays
 * - Logging of exceptions
 */

var crypto = require("crypto"),
  winston = require("winston");

const logger = winston.createLogger({
  format: winston.format.combine(
    winston.format.splat(),
    winston.format.simple()
  ),
  transports: [
    new winston.transports.Console({
      format: winston.format.simple(),
      handleExceptions: true
    })
  ]
});

const demonstrateKeyBasedSymmetricEncryption = () => {
  try {
    // replace with your actual String
    let exampleString =
      "Text that is going to be sent over an insecure channel and must be encrypted at all costs!";
    // the key used for encryption and decryption, assign your key here
    // if none is assigned a random one is generated
    // keylength adheres to the "ECRYPT-CSA Recommendations" on "www.keylength.com"
    let key = null;
    if (key === null) {
      key = crypto.randomBytes(32);
    }

    // create random initialization vector
    var iv = crypto.randomBytes(16);

    // encrypt the Text
    var cipher = crypto.createCipheriv("aes-256-gcm", key, iv);
    var encrypted = cipher.update(exampleString, "utf8", "base64");
    encrypted += cipher.final("base64");
    let authTag = cipher.getAuthTag();

    // decrypt the Text
    var decipher = crypto.createDecipheriv("aes-256-gcm", key, iv);
    decipher.setAuthTag(authTag);
    var decrypted = decipher.update(encrypted, "base64", "utf8");
    decrypted += decipher.final("utf8");

    logger.info(
      "Decrypted String and original String are the same: %s",
      exampleString.localeCompare(decrypted) === 0 ? "yes" : "no"
    );
  } catch (error) {
    logger.error(error.message);
  }
};

demonstrateKeyBasedSymmetricEncryption();

// for unit testing purposes
module.exports = { demonstrateKeyBasedSymmetricEncryption, logger };