Adding GCM encryption support.

This adds GCM encryption which can be toogled on via new client option `encryptionVersion` (1 = ECB, 2 = GCM). It is needed for newer firmware versions and replaces existing ECB for all pack encryptions BUT the scan command, which still runs on ECB for compatibility.

Tested on firmware 362001065279+U-WB05RT13V1.23

src/client-options.js

@@ -14,6 +14,7 @@
  * @property {number} pollingInterval=3000 - Device properties polling interval
  * @property {number} pollingTimeout=1000 - Device properties polling timeout, emits `no_response` events in case of no response from HVAC device for a status request
  * @property {boolean} debug=false - Trace debug information
+ * @property {number} encryptionVersion=1 - The encryption method to use: 1 AES-ECB; 2: AES-GCM
  */
 const CLIENT_OPTIONS = {
     host: '192.168.1.255',
@@ -24,6 +25,7 @@ const CLIENT_OPTIONS = {
     pollingInterval: 3000,
     pollingTimeout: 1000,
     debug: false,
+    encryptionVersion: 1,
 };
 
 module.exports = {

src/client.js

@@ -5,7 +5,7 @@ const EventEmitter = require('events');
 const diff = require('object-diff');
 const clone = require('clone');
 
-const { EncryptionService } = require('./encryption-service');
+const { EncryptionService, EncryptionServiceGCM } = require('./encryption-service');
 const { PROPERTY } = require('./property');
 const { PROPERTY_VALUE } = require('./property-value');
 const { CLIENT_OPTIONS } = require('./client-options');
@@ -139,19 +139,36 @@ class Client extends EventEmitter {
          */
         this._transformer = new PropertyTransformer();
 
-        /**
-         * @type {EncryptionService}
-         * @private
-         */
-        this._encryptionService = new EncryptionService();
-
         /**
          * Client options
          *
          * @type {CLIENT_OPTIONS}
          * @private
          */
         this._options = { ...CLIENT_OPTIONS, ...options };
+
+        /**
+         * Encryption service based on encryption version.
+         * @type {EncryptionService}
+         * @private
+         */
+        switch (this._options.encryptionVersion) {
+            case 1:
+                this._encryptionService = new EncryptionService();
+                break;
+            case 2:
+                this._encryptionService = new EncryptionServiceGCM();
+                break;
+            default:
+                this._encryptionService = new EncryptionService();
+        }
+
+        /**
+         * Needed for scan request handling
+         * @type {EncryptionService}
+         * @private
+         */
+        this._encryptionServiceV1 = new EncryptionService();
 
         /**
          * @private
@@ -370,6 +387,7 @@ class Client extends EventEmitter {
                 t: 'bind',
                 uid: 0,
             }),
+            tag: this._encryptionService.getTag(),
         });
     }
 
@@ -422,6 +440,7 @@ class Client extends EventEmitter {
             t: 'pack',
             uid: 0,
             pack: this._encryptionService.encrypt(message),
+            tag: this._encryptionService.getTag(),
         });
     }
 
@@ -456,7 +475,14 @@ class Client extends EventEmitter {
         this._trace('IN.MSG', message);
 
         // Extract encrypted package from message using device key (if available)
-        const pack = this._unpack(message);
+        let pack;
+        if (!this._cid) {
+            //scan responses are always on v1
+            pack = this._encryptionServiceV1.decrypt(message);
+        } else {
+            //use set encryption method
+            pack = this._encryptionService.decrypt(message);
+        }
 
         // If package type is response to handshake
         if (pack.t === 'dev') {

src/encryption-service.js

@@ -57,8 +57,90 @@ class EncryptionService {
         const str = cipher.update(JSON.stringify(output), 'utf8', 'base64');
         return str + cipher.final('base64');
     }
+
+    /**
+     * Required for GCM, return nothing here.
+     */
+    getTag() {
+        return undefined;
+    }
+}
+
+/**
+ * Nonce and AAD values for GCM encryption
+ */
+const GCM_NONCE = Buffer.from('5440784449675a516c5e6313',"hex"); //'\x54\x40\x78\x44\x49\x67\x5a\x51\x6c\x5e\x63\x13';
+const GCM_AEAD = Buffer.from('qualcomm-test');
+
+class EncryptionServiceGCM {
+
+    /**
+     * @param {string} [key] AES key
+     */
+    constructor(key = '{yxAHAY_Lm6pbC/<') {
+        /**
+         * Device crypto-key
+         * @type {string}
+         * @private
+         */
+        this._key = key;
+    }
+
+    /**
+     * @param {string} key
+     */
+    setKey(key) {
+        this._key = key;
+    }
+
+    /**
+     * @returns {string}
+     */
+    getKey() {
+        return this._key;
+    }
+
+    /**
+     * Decrypt UDP message
+     * @param {object} input Response object
+     * @param {string} input.pack Encrypted JSON string
+     * @param {string} input.tag Auth Tag for GCM decryption
+     */
+    decrypt(input) {
+        const decipher = crypto.createDecipheriv('aes-128-gcm', this._key, GCM_NONCE);
+        decipher.setAAD(GCM_AEAD);
+        if (input.tag) {
+            const decTag = Buffer.from(input.tag, 'base64');
+            decipher.setAuthTag(decTag);
+        }
+        const str = decipher.update(input.pack, 'base64', 'utf8');
+        return JSON.parse(str + decipher.final('utf8'));
+    }
+
+    /**
+     * Encrypt UDP message. Sets _encTag to be received before sending with getTag() and added to message.
+     * @param {object} output Request object
+     */
+    encrypt(output) {
+        const cipher = crypto.createCipheriv('aes-128-gcm', this._key, GCM_NONCE);
+        cipher.setAAD(GCM_AEAD);
+        const str = cipher.update(JSON.stringify(output), 'utf8', 'base64');
+        const outstr = str + cipher.final('base64');
+        this._encTag = cipher.getAuthTag().toString('base64').toString("utf-8");
+        return outstr
+    }
+
+    /**
+     * Receive and clear the last generated tag
+     */
+    getTag() {
+        const tmpTag = this._encTag;
+        this._encTag = undefined;
+        return tmpTag;
+    }
 }
 
 module.exports = {
     EncryptionService,
+    EncryptionServiceGCM,
 };