Encrypt a private key for mobile apps (AES_PBKF2)

@param {string} password - A wallet password
@param {string} privateKey - An account private key

@return {object} - The encrypted data
function(password, privateKey) {
    // Errors
    if (!password || !privateKey) throw new Error('Missing argument !');
    //if (!Helpers.isPrivateKeyValid(privateKey)) throw new Error('Private key is not valid !');
    // Processing
    let salt = CryptoJS.lib.WordArray.random(256 / 8);
    let key = CryptoJS.PBKDF2(password, salt, {
        keySize: 256 / 32,
        iterations: 2000
    });
    let iv = nacl.randomBytes(16)
    let encIv = {
        iv: ua2words(iv, 16)
    };
    let encrypted = CryptoJS.AES.encrypt(CryptoJS.enc.Hex.parse(privateKey), key, encIv);
    // Result
    return {
        encrypted: convert.uint8ToHex(iv) + encrypted.ciphertext,
        salt:  salt.toString()
    }
}