AES encryption + decryption

encryption.js

var aesjs = require('aes-js');
var exports = module.exports = {}

const blockSize = 16;

function pad(s) {
    const len = blockSize - s.length % blockSize;
    return s.padEnd(blockSize, String.fromCharCode(len));
}

function unpad(data) {
    const code = data[data.length - 1];
    return data.slice(0, -code);
}

function encrypt(data, secret) {
    if (secret === undefined) {
        throw Error('Secret key not provided');
    }
    const iv = crypto.randomBytes(blockSize);
    const key = secret.split('').map(chr => chr.charCodeAt());

    const bytes = aesjs.utils.utf8.toBytes(pad(data));
    const aesCbc = new aesjs.ModeOfOperation.cbc(key, iv);

    let result = aesCbc.encrypt(bytes);
    const buffer = Buffer.concat([iv, result]);
    return buffer.toString('base64');
}

function decrypt(data, secret) {
    if (secret === undefined) {
        throw Error('Secret key not provided');
    }

    const key = secret.split('').map(chr => chr.charCodeAt());

    buffer = Buffer.from(data, 'base64')
    iv = buffer.slice(0, blockSize);
    cbc = new aesjs.ModeOfOperation.cbc(key, iv);
    let result = cbc.decrypt(buffer.slice(blockSize));
    result = unpad(result);
    return aesjs.utils.utf8.fromBytes(result);
}
exports.encrypt = encrypt;
exports.decrypt = decrypt;