zaes-js

AES encryption implementation.

Attention!

Before you will learn this lib, I highly recommend you to go through other aes implementations in js, because I imlemented zaes.js only because other libraries did not meet my requirements. Some of them you can find here.

Installation

npm install zaes-js

Usage

Usage of zaes-js on browser is similar to usage in nodejs. The only difference is initialization.

Initialization

Node js 6+

var aes = require("zaes-js");

Browser

There is bundle.zaes.js in ./node_modules/zaes-js/ directory.

Include it on your html:

<script src="/path/to/bundle.zaes.js"></script>

After loading script there will be aes global varialbe available.

Generating key

To encrypt string with AES, you always need a key. You can use own key or generate it using aes.generateKey function that returns secure random key.

Note!

If you using your own key be sure that is valid. Valid means that it is array of bytes(0-255) with length 16, 24 or 32(for 128, 192 and 256 bit keys respectively).

var keyLength = 16; // Or it can be 24 or 32
var key = aes.generateKey(keyLength);

key -> [90, 50, 232, 234, 132, 249, 197, 211, 125, 63, 231, 52, 35, 126, 190, 42]

Encrypting

Use aes.encrypt(bytes, key) function to encrypt array of bytes.

Where bytes is array of bytes with any length and key is AES key to encrypt with.

var bytes = [122, 97, 101, 115, 32, 106, 115];
var encrypted = aes.encrypt(bytes, key);

encrypted -> [32, 223, 97, 187, 151, 149, 181, 126, 92, 222, 193, 174, 219, 39, 60, 231]

Decrypting

Use aes.decrypt(bytes, key) to decrypt data that was encrypted with passed key.

var decrypted = aes.decrypt(encrypted, key);

decrypted -> [122, 97, 101, 115, 32, 106, 115]

Utils

You read above how to encrypt/decrypt bytes. But what if you will want string to be encrypted.

For this case zaes-js includes utils module, that allows to convert strings to bytes and bytes to strings.

See examples below for single byte characters in string(UTF8, ASCII).

var message = "my top secret message";
var bytes = aes.utils.stringToBytes(message);

var key = aes.generateKey(32); // top secret key

var cipher = aes.encrypt(bytes);

var initialMessage = aes.utils.bytesToString(aes.decrypt(bytes, key));

If your string contains character which coded with 2 or more bytes you need to specify it in param for stringToBytes and bytesToString functions.

var bytesPerChar = 2;
var message = "鸠尠㜂᠆삮";  // chinese characters codes with 2 bytes
var bytes = aes.utils.stringToBytes(message, bytesPerChar);

var initMessage = aes.utils.bytesToString(bytes, bytesPerChar);

If you don't sure about bytesPerChar param you can use detectBytesPerChar function.

var message = "strange message, with 鸠尠㜂᠆삮 characters";
var bytesPerChar = aes.utils.detectBytesPerChar(message); // it will return 2, because of chinese chars

// then use bytesPerChar in stringToBytes or bytesToString