From dfb12e6d46e29cadaff39b5e9d6625a708502d05 Mon Sep 17 00:00:00 2001
From: Ernst79 <e.klamer@gmail.com>
Date: Fri, 14 Jul 2023 21:41:18 +0200
Subject: [PATCH] fix: decryption bug fixed

---
 src/bthome_ble/parser.py | 10 +++++++---
 tests/test_parser_v2.py  | 20 ++++++++++++++++++--
 2 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/src/bthome_ble/parser.py b/src/bthome_ble/parser.py
index 1d8fa6b..242a8a4 100644
--- a/src/bthome_ble/parser.py
+++ b/src/bthome_ble/parser.py
@@ -333,7 +333,9 @@ def _parse_bthome_v2(
             bthome_mac = bytes.fromhex(mac_readable.replace(":", ""))
             # Decode encrypted payload
             try:
-                payload = self._decrypt_bthome(payload, bthome_mac, sw_version)
+                payload = self._decrypt_bthome(
+                    payload, bthome_mac, sw_version, adv_info
+                )
             except (ValueError, TypeError):
                 return True
 
@@ -500,7 +502,9 @@ def _parse_payload(self, payload: bytes, sw_version: int) -> bool:
 
         return True
 
-    def _decrypt_bthome(self, data: bytes, bthome_mac: bytes, sw_version: int) -> bytes:
+    def _decrypt_bthome(
+        self, data: bytes, bthome_mac: bytes, sw_version: int, adv_info: int = 65
+    ) -> bytes:
         """Decrypt encrypted BTHome BLE advertisements"""
         if not self.bindkey:
             self.bindkey_verified = False
@@ -521,7 +525,7 @@ def _decrypt_bthome(self, data: bytes, bthome_mac: bytes, sw_version: int) -> by
         if sw_version == 1:
             uuid = b"\x1e\x18"
         else:
-            uuid = b"\xd2\xfc\x41"
+            uuid = b"\xd2\xfc" + bytes([adv_info])
         encrypted_payload = data[:-8]
         count_id = data[-8:-4]
         mic = data[-4:]
diff --git a/tests/test_parser_v2.py b/tests/test_parser_v2.py
index 9b72016..879d395 100644
--- a/tests/test_parser_v2.py
+++ b/tests/test_parser_v2.py
@@ -454,9 +454,9 @@ def test_bthome_with_mac(caplog):
 def test_bthome_with_mac_encrypted():
     """Test BTHome parser with mac address in payload plus encryption."""
     bindkey = "231d39c1d7cc1ab1aee224cd096db932"
-    data_string = b"\x43\xa5\x80\x8f\xe6\x48\x54\xa4\x72\x66\xc9\x5f\x73\x00\x11\x22\x33\x78\x23\x72\x14"  # noqa: E501
+    data = b"\x43\xa5\x80\x8f\xe6\x48\x54\xf1\x96\xc0\x6f\xfb\x49\x00\x11\x22\x33\xf0\x8e\xcb\xde"
     advertisement = bytes_to_service_info(
-        data_string,
+        data,
         local_name="TEST DEVICE",
         address="54:48:E6:8F:80:A5",
     )
@@ -1571,6 +1571,22 @@ def test_bthome_invalid_button_event(caplog):
     )
 
 
+def test_encrypted_shelly_blu_button_event(caplog):
+    """Test BTHome parser for an encrypted shelly blu button event."""
+    bindkey = "90bffd73cb6b26ef58a7a8eba9232036"
+    data_string = b"\x45\x0a\xeb\x84\x46\x7f\x85\xba\x01\x00\x00\x31\x88\x78\x8c"
+
+    advertisement = bytes_to_service_info(
+        data_string,
+        local_name="SBBT-002C",
+        address="B4:35:22:F5:3D:A4",
+    )
+
+    device = BTHomeBluetoothDeviceData(bindkey=bytes.fromhex(bindkey))
+    assert device.supported(advertisement)
+    assert device.bindkey_verified
+
+
 def test_bthome_distance_millimeters(caplog):
     """Test BTHome parser for distance in millimeters."""
     data_string = b"\x40\x40\x0C\x00"