Alice

Cryptografic message exchanging protocol based on RSA and AES.

Installation

$ npm install alice-crypto --save

Usage

const Alice = require('alice-crypto');

const alice = new Alice();
const bob = new Alice();

const secretMessage = 'Cats are cool, but dogs are better!';

// Only Bob can decipher the contents of this message.
// May be sent over insecure channels.
const cipheredMessage = alice.write(secretMessage, bob.pubkey);

const decipheredMessage = bob.read(cipheredMessage);

assert(decipheredMessage === secretMessage);

API

new Alice(options)

Returns a new instance of Alice.

Note: It may take a few seconds to generate the RSA keypair, which is a blocking operation. It is recommended to create the new instance as a singleton during your app's initialization routine.

options Object

rsaKeyBits Integer: Length of the RSA keypair. Default: 2048.

aesAlgorithm String: AES algorithm to pass to node's crypto.createCipheriv and crypto.createDecipheriv functions. Default: "aes256".

aesKeyBytes Integer: Length of the AES key to be randomly generated with each encryption. Default: 32.

aesIvBytes Integer: Length of the AES initialization vector to be randomly generated with each encryption. Default: 16.

instance.pubkey

The public key string to be shared between instances of Alice over insecure channels.

instance.write(message String, pubkey String, [sign Boolean])

Returns an object that can be sent over insecure channels to the owner of pubkey. If sign is set to true, will include signature.

instance.read(ciphered Object, [pubkey String])

Returns a string containing the original message. If pubkey is present, will verify the signature of the message and throw an error if invalid.

Example server usage

This sample would allow two servers running instances of Alice to communicate securely over open channels.

const Alice = require('alice-crypto');
const express = require('express');
const bodyParser = require('body-parser');
const request = require('request');

const alice = new Alice();

const app = express();
app.use(bodyParser());

const thisHostname = 'alice.example.com';
const bobHostname = 'bob.example.com';

const importantMessage =
  'Bob, my bank account password is 123456. Nobody else must know!';

function sendMessage (message, hostname) {
  request(`http://${hostname}/pubkey`, (err, response, body) => 
    const pubkey = body;
    const ciphered = alice.write(message, pubkey);

    request.post(`http://${hostname}/secret-message`,
      { form: { message: JSON.stringify(ciphered) } });
  );
}

app.get('/pubkey', (req, res, next) => {
  res.send(alice.pubkey);
}

app.post('/secret-message', (req, res, next) => {
  const ciphered = JSON.parse(req.body.message);
  const message = alice.read(ciphered);

  console.log(message);
}

app.listen(80);

sendMessage(importantMessage, bobHostname);

License

MIT