shannon

Pure javascript implementation of Shannon stream cipher. No-brainer port of shannon.

Shannon cipher is used in Spotify Connect to encrypt communication between player and Spotify AP server. Shannon cipher is variant of Sober stream cipher.

Example

Encryption

const Shannon = require('shannon');

let key = Buffer.from([0x65, 0x87, 0xd8, 0x8f, 0x6c, 0x32, 0x9d, 0x8a, 0xe4, 0x6b]);
let message = 'My secret message';

let cipher = new Shannon(key);
let message = cipher.encrypt(message);
// message contains ciphertext now
let mac = cipher.final(Buffer.alloc(16));
// mac contains MAC of the message

Decryption

const Shannon = require('shannon');

let key = Buffer.from([0x65, 0x87, 0xd8, 0x8f, 0x6c, 0x32, 0x9d, 0x8a, 0xe4, 0x6b]);
// message is encrypted
let message = Buffer.from([0x91, 0x9d, 0xa9, 0xb6, 0x29, 0xfc, 0x9c, 0xdd, 0x17, 0x8c, 0x15, 0x31, 0x9a, 0xae, 0xcc, 0x6e, 0xd4]);
let receivedMac = Buffer.from([0xbe, 0x7b, 0xef, 0x39, 0xee, 0xfe, 0x54, 0xfd, 0x8d, 0xb0, 0xbc, 0x6f, 0xd5, 0x30, 0x35, 0x19]);
let cipher = new Shannon(key);
let message = cipher.decrypt(message);
// message contains plaintext now
let mac = cipher.final(Buffer.alloc(16));
if (Buffer.compare(mac, receivedMac)) {
	console.log("MAC OK")
}