AES-GCM-256 Encryption & Decryption Using NODE

gist.js

const crypto = require('crypto');

const generateMasterKey = function (bytes) {
    return crypto.randomBytes(bytes).toString('base64')
}

const encryptAes256Gcm = (text, cryptoConfigObject) => {
    try {
        // random initialization vector
        const iv = crypto.randomBytes(16);
        // random salt
        const salt = crypto.randomBytes(64);
        // derive encryption key
        const key = crypto.pbkdf2Sync(cryptoConfigObject.masterKey, salt, cryptoConfigObject.iterations, cryptoConfigObject.keyLength, cryptoConfigObject.digest);
        // AES 256 GCM Mode
        const cipher = crypto.createCipheriv('aes-256-gcm', key, iv);
        // encrypt the given text
        const encrypted = Buffer.concat([cipher.update(text, 'utf8'), cipher.final()]);
        // extract the auth tag
        const tag = cipher.getAuthTag();
        // generate output
        return Buffer.concat([salt, iv, tag, encrypted]).toString('base64')
    } catch (err) {
        return err
    }
}

/**
 * Decrypts text by given key
 * @param String base64 encoded input data
 * @param Buffer masterkey
 * @returns String decrypted (original) text
 */
const decryptAes256Gcm = (encdata, cryptoConfigObject) => {
    try {
        // base64 decoding
        const bData = Buffer.from(encdata, 'base64');
        // convert data to buffers
        const salt = bData.slice(0, 64);
        const iv = bData.slice(64, 80);
        const tag = bData.slice(80, 96);
        const text = bData.slice(96);
        // derive key using; 32 byte key length
        const key = crypto.pbkdf2Sync(cryptoConfigObject.masterKey, salt, cryptoConfigObject.iterations, cryptoConfigObject.keyLength, cryptoConfigObject.digest);
        // AES 256 GCM Mode
        const decipher = crypto.createDecipheriv('aes-256-gcm', key, iv);
        decipher.setAuthTag(tag);
        return decipher.update(text, 'binary', 'utf8') + decipher.final('utf8')
    }
    catch (err) {
        return err
    }
}

// =========================== module ends here =======================

const toFetchFromDb = {
    "masterKey": "sfcpnnjFG6dULJfo1BEGqczpfN0SmwZ6bgKO5FcDRfI=",
    "iterations": 2333,
    "keyLength": 32,
    "digest": "sha512"
}

// string data which will be encrypted and then decrypted
var dataToEncrypt = 'some string to encrypt and then decrypt'

const encryptedData = encryptAes256Gcm(dataToEncrypt, toFetchFromDb)

console.log('encrypted data ->', encryptedData)
console.log('data encrypted, now decrypting it ...')
console.log('decrypted data ->', decryptAes256Gcm(encryptedData, toFetchFromDb))


// uncomment below console statememt to generate new masterkey
// console.log('your masterKey is :', generateMasterKey(32))