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Secure multi-environment configurations with encrypted secrets.


  1. Encrypt sensitive data in your JSON configuration file. Most easy way to do this is using the secure-config-tool. For more details please see generating encrypted values and naming conventions.

      "database": {
        "host": "",
        "user": "ENCRYPTED|50ceed2f97223100fbdf842ecbd4541f|df9ed9002bfc956eb14b1d2f8d960a11",
        "pass": "ENCRYPTED|8fbf6ded36bcb15bd4734b3dc78f2890|7463b2ea8ed2c8d71272ac2e41761a35"
  2. Use your configuration in the code.

    const conf = require('@tsmx/secure-config');
    function MyFunc() {
      let dbHost = conf.database.host; // = ''
      let dbUser = conf.database.user; // = 'MySecretDbUser'
      let dbPass = conf.database.pass; // = 'MySecretDbPass'
  3. Run your app. See below for different options on how to pass the key.

    $ node app.js

A fully working example project is also available on GitHub.

To get all information please also check out the full documentation.

Naming conventions

You can have multiple configuration files for different environments or stages. They are distinguished by the environment variable NODE_ENV. The basic configuration file name is config.json if this variable is not present. If it is present, a configuration file with the name config-[NODE_ENV].json is used. An exception will be thrown if no configuration file is found.

All configuration files must be located in a conf/ directory of the current running app, meaning a direct subdirectory of the current working directory (CWD/conf/).

Example structure

Stage Value of NODE_ENV Filename
Development not set conf/config.json
Production production conf/config-production.json
Test test conf/config-test.json

Resulting folders/files setup:

├── conf/
│   ├── config.json
│   ├── config-production.json
│   └── config-test.json
├── app.js
└── package.json

Injecting the decryption key

The key for decrypting the encrypted values is derived from an environment variable named CONFIG_ENCRYPTION_KEY. You can set this variable whatever way is most suitable, e.g.

  • set/export in the command line or in your bash pofile
    export CONFIG_ENCRYPTION_KEY=0123456789qwertzuiopasdfghjklyxc
  • using an env block in your VS-Code launch configuration
        "CONFIG_ENCRYPTION_KEY": "0123456789qwertzuiopasdfghjklyxc"
  • using an env block in your deployment descriptor, e.g. app.yaml for Google App Engine
      CONFIG_ENCRYPTION_KEY: "0123456789qwertzuiopasdfghjklyxc"
  • for testing with Jest I recommend to create a test key and set it globally for all tests in the jest.config.js, e.g.
    process.env['CONFIG_ENCRYPTION_KEY'] = '0123456789qwertzuiopasdfghjklyxc';
    module.exports = {
        testEnvironment: 'node'
  • etc.

More examples are available in the full documentation.

The key length must be 32 bytes! The value set in CONFIG_ENCRYPTION_KEY has to be:

  • a string of 32 characters length, or
  • a hexadecimal value of 64 characters length (= 32 bytes)

Otherwise an error will be thrown.

Examples of valid key strings:

  • 32 byte string: MySecretConfigurationKey-123$%&/
  • 32 byte hex value: 9af7d400be4705147dc724db25bfd2513aa11d6013d7bf7bdb2bfe050593bd0f

Different keys for each configuration environment are strongly recommended.

Generating encrypted entries

Option 1: secure-config-tool

For better convenience I provided a very basic secure-config-tool to easily generate the encrypted entries.

Option 2: NodeJS crypto functions

You can simply use crypto functions from NodeJS with the following snippet to create the encrypted entries:

const crypto = require('crypto');
const algorithm = 'aes-256-cbc';
function encrypt(value) {
  let iv = crypto.randomBytes(16);
  let key = Buffer.from('YOUR_KEY_HERE');
  let cipher = crypto.createCipheriv(algorithm, key, iv);
  let encrypted = cipher.update(value);
  encrypted = Buffer.concat([encrypted, cipher.final()]);
  return 'ENCRYPTED|' + iv.toString('hex') + '|' + encrypted.toString('hex');


The generated encrypted entry must always have the form: ENCRYPTED | IV | DATA.

Part Description
ENCRYPTED The prefix ENCRYPTED used to identify configuration values that must be decrypted.
IV The ciphers initialization vector (IV) that was used for encryption. Hexadecimal value.
DATA The AES-256-CBC encrypted value. Hexadecimal value.


npm install
npm test


npm i @tsmx/secure-config

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