shannon

Modern 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

import { Shannon } from 'shannon';

let key = new Uint8Array([0x65, 0x87, 0xd8, 0x8f, 0x6c, 0x32, 0x9d, 0x8a, 0xe4, 0x6b]);
let message = new TextEncoder().encode('My secret message');

let cipher = new Shannon(key);
let message = cipher.encrypt(message);
// message contains ciphertext now
let mac = cipher.final(new Uint8Array(16));
// mac contains MAC of the message

Decryption

import { Shannon } from 'shannon';

let key = new Uint8Array([0x65, 0x87, 0xd8, 0x8f, 0x6c, 0x32, 0x9d, 0x8a, 0xe4, 0x6b]);
// message is encrypted
let message = new Uint8Array([0x91, 0x9d, 0xa9, 0xb6, 0x29, 0xfc, 0x9c, 0xdd, 0x17, 0x8c, 0x15, 0x31, 0x9a, 0xae, 0xcc, 0x6e, 0xd4]);
let receivedMac = new Uint8Array([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(new Uint8Array(16));
if (buffersEqual(mac, receivedMac)) {
	console.log("MAC OK")
}