Merge pull request #655 from nospam2k/patch-2

Update cipher.js

lib/cipher.js

@@ -16,7 +16,7 @@ class TuyaCipher {
   }
 
   /**
-   * Sets the session key used for Protocol 3.4
+   * Sets the session key used for Protocol 3.4, 3.5
    * @param {Buffer} sessionKey Session key
    */
   setSessionKey(sessionKey) {
@@ -37,6 +37,10 @@ class TuyaCipher {
       return this._encrypt34(options);
     }
 
+    else if (this.version === '3.5') {
+      return this._encrypt35(options);
+    }
+
     return this._encryptPre34(options);
   }
 
@@ -82,6 +86,32 @@ class TuyaCipher {
     return encrypted;
   }
 
+  /**
+   * Encrypt data for protocol 3.5
+   * @param {Object} options Options for encryption
+   * @param {String} options.data data to encrypt
+   * @param {Boolean} [options.base64=true] `true` to return result in Base64
+   * @returns {Buffer|String} returns Buffer unless options.base64 is true
+   */
+  _encrypt35(options) {
+    let encrypted;
+    let localIV = Buffer.from((Date.now() * 10).toString().substring(0, 12));
+    if(options.iv !== undefined) localIV = options.iv.slice(0, 12);
+
+    const cipher = crypto.createCipheriv('aes-128-gcm', this.getKey(), localIV);
+    if(options.aad !== undefined)
+    {
+      cipher.setAAD(options.aad);
+      encrypted = Buffer.concat([localIV, cipher.update(options.data), cipher.final(), cipher.getAuthTag(), Buffer.from([0x00, 0x00, 0x99, 0x66])]);
+    }
+    else
+    {
+      encrypted = Buffer.concat([cipher.update(options.data), cipher.final()]);
+    }
+
+    return encrypted;
+  }
+
   /**
   * Decrypts data.
   * @param {String|Buffer} data to decrypt
@@ -93,6 +123,10 @@ class TuyaCipher {
       return this._decrypt34(data);
     }
 
+    else if (this.version === '3.5') {
+      return this._decrypt35(data);
+    }
+
     return this._decryptPre34(data);
   }
 
@@ -180,6 +214,52 @@ class TuyaCipher {
     }
   }
 
+  /**
+   * Decrypts data for protocol 3.5
+   * @param {String|Buffer} data to decrypt
+   * @returns {Object|String}
+   * returns object if data is JSON, else returns string
+   */
+  _decrypt35(data) {
+    let result;
+    let header = data.slice(0, 14);
+    let iv = data.slice(14, 26);
+    let tag = data.slice(data.length - 16);
+    data = data.slice(26, data.length - 16);
+
+    try {
+      const decipher = crypto.createDecipheriv('aes-128-gcm', this.getKey(), iv);
+      decipher.setAuthTag(tag);
+      decipher.setAAD(header);
+
+      result = Buffer.concat([decipher.update(data), decipher.final()]);
+      result = result.slice(4); // remove 32bit return code
+    } catch (_) {
+      throw new Error('Decrypt failed');
+    }
+
+    // Try to parse data as JSON,
+    // otherwise return as string.
+    // 3.5 protocol
+    // {"protocol":4,"t":1632405905,"data":{"dps":{"101":true},"cid":"00123456789abcde"}}
+    try {
+      if (result.indexOf(this.version) === 0) {
+        result = result.slice(15);
+      }
+
+      const res = JSON.parse(result);
+      if ('data' in res) {
+        const resData = res.data;
+        resData.t = res.t;
+        return resData; // Or res.data // for compatibility with tuya-mqtt
+      }
+
+      return res;
+    } catch (_) {
+      return result;
+    }
+  }
+
   /**
   * Calculates a MD5 hash.
   * @param {String} data to hash
@@ -192,14 +272,14 @@ class TuyaCipher {
 
   /**
    * Gets the key used for encryption/decryption
-   * @returns {String} sessionKey (if set for protocol 3.4) or key
+   * @returns {String} sessionKey (if set for protocol 3.4, 3.5) or key
    */
   getKey() {
     return this.sessionKey === null ? this.key : this.sessionKey;
   }
 
   /**
-   * Returns the HMAC for the current key (sessionKey if set for protocol 3.4 or key)
+   * Returns the HMAC for the current key (sessionKey if set for protocol 3.4, 3.5 or key)
    * @param {Buffer} data data to hash
    * @returns {Buffer} HMAC
    */