From 2f04b69f38c680f3a223d9d976d7ab9d16730692 Mon Sep 17 00:00:00 2001
From: KnugiHK <24708955+KnugiHK@users.noreply.github.com>
Date: Mon, 5 Sep 2022 12:48:36 +0800
Subject: [PATCH] A more concrete way to determine database offset

---
 Whatsapp_Chat_Exporter/extract.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Whatsapp_Chat_Exporter/extract.py b/Whatsapp_Chat_Exporter/extract.py
index f2aebf1..a6b6469 100644
--- a/Whatsapp_Chat_Exporter/extract.py
+++ b/Whatsapp_Chat_Exporter/extract.py
@@ -112,7 +112,8 @@ def decrypt_backup(database, key, output, crypt=Crypt.CRYPT14):
             raise ValueError("The crypt15 file must be at least 131 bytes")
         t1 = t2 = None
         iv = database[8:24]
-        db_ciphertext = database[131:]
+        db_offset = database[0] + 2 # Skip protobuf + protobuf size and backup type
+        db_ciphertext = database[proto_len:]
 
     if t1 != t2:
         raise ValueError("The signature of key file and backup file mismatch")