Encryption Example

gistfile1.txt

const crypto = require('crypto')
const owasp = require('owasp-password-strength-test')
owasp.config({
    allowPassphrases: true,
    maxLength: 128,
    minLength: 16,
    minPhraseLength: 24,
    minOptionalTestsToPass: 4,
})

/**
 * Generate a pbkdf2 key from a user password and salt
 * @param {String} password     A user entered password with will be used to derive a key
 * @param {Buffer} salt         Either a new salt for a new key or the old salt to re-generate an old key
 * @return {Buffer}             A buffer derived from the password
 */
function createKey(password, salt) {
    const passwordStrength = owasp.test(password)

    if (!passwordStrength.strong) {
        throw new Error(passwordStrength.errors[0])
    }

    // const key = crypto.createHash('sha256').update(password).digest()
    const key = crypto.pbkdf2Sync(password, salt, 10000, 32, 'sha512')
    return key
}

/**
 * Encrypt a data string with an encryption key
 * @param {String} data         The data to be encrypted
 * @param {String} password     A password to be used for encrypting
 * @return {String}             The encrypted data
 */
function encrypt(data, password) {
    const iv = crypto.randomBytes(16)
    const salt = crypto.randomBytes(32)
    const key = createKey(password, salt)
    const cipher = crypto.createCipheriv('aes-256-cbc', key, iv)
    let encrypted = cipher.update(data)

    encrypted = Buffer.concat([encrypted, cipher.final()])

    return [iv.toString('hex'), salt.toString('hex'), encrypted.toString('hex')].join(':')
}

/**
 * Decryt data with the encryption key used to encrypt it
 * @param {String} data         The data to be decrypted
 * @param {String} password     A key to be used for encrypting
 * @return {String}             The decrypted data
 */
function decrypt(data, password) {
    const textParts = data.split(':')
    const iv = new Buffer(textParts[0], 'hex')
    const salt = new Buffer(textParts[1], 'hex')
    const encryptedText = new Buffer(textParts[2], 'hex')
    const key = createKey(password, salt)
    const decipher = crypto.createDecipheriv('aes-256-cbc', key, iv)
    let decrypted = decipher.update(encryptedText)

    decrypted = Buffer.concat([decrypted, decipher.final()])

    return decrypted.toString()
}

module.exports = {
    decrypt,
    encrypt,
}