diff --git a/Whatsapp_Chat_Exporter/__main__.py b/Whatsapp_Chat_Exporter/__main__.py
index feb4763..ee917ca 100644
--- a/Whatsapp_Chat_Exporter/__main__.py
+++ b/Whatsapp_Chat_Exporter/__main__.py
@@ -40,7 +40,7 @@ def main():
         "--backup",
         dest="backup",
         default=None,
-        help="Path to iPhone backup")
+        help="Path to Android (must be used together with -k)/iPhone WhatsApp backup")
     parser.add_option(
         "-o",
         "--output",
@@ -60,6 +60,13 @@ def main():
         dest='db',
         default=None,
         help="Path to database file")
+    parser.add_option(
+        '-k',
+        '--key',
+        dest='key',
+        default=None,
+        help="Path to key file"
+    )
     (options, args) = parser.parse_args()
 
     if options.android and options.iphone:
@@ -80,6 +87,16 @@ def main():
             msg_db = "msgstore.db"
         else:
             msg_db = options.db
+        if options.key is not None:
+            if options.backup is None:
+                print("You must specify the backup file with -b")
+                return False
+            print("Decryption key specified, decrypting WhatsApp backup...")
+            key = open(options.key, "rb").read()
+            db = open(options.backup, "rb").read()
+            if not extract.decrypt_backup(db, key, msg_db):
+                print("Dependencies of decrypt_backup are not present. For details, see README.md")
+                return False
         if options.wa is None:
             contact_db = "wa.db"
         else:
diff --git a/Whatsapp_Chat_Exporter/extract.py b/Whatsapp_Chat_Exporter/extract.py
index 0e133d8..877fdb8 100644
--- a/Whatsapp_Chat_Exporter/extract.py
+++ b/Whatsapp_Chat_Exporter/extract.py
@@ -10,6 +10,13 @@ import re
 import pkgutil
 from datetime import datetime
 from mimetypes import MimeTypes
+try:
+    import zlib
+    from Crypto.Cipher import AES
+except ModuleNotFoundError:
+    support_backup = False
+else:
+    support_backup = True
 
 
 def determine_day(last, current):
@@ -21,6 +28,32 @@ def determine_day(last, current):
         return current
 
 
+def decrypt_backup(database, key, output):
+    if not support_backup:
+        return False
+    if len(key) != 158:
+        raise ValueError("The key file must be 158 bytes")
+    if len(database) < 191:
+        raise ValueError("The database file must be at least 191 bytes")
+    t1 = key[30:62]
+    t2 = database[15:47]
+    if t1 != t2:
+        raise ValueError("The signature of key file and backup file mismatch")
+
+    iv = database[67:83]
+    db_ciphertext = database[191:]
+    main_key = key[126:]
+    cipher = AES.new(main_key, AES.MODE_GCM, iv)
+    db_compressed = cipher.decrypt(db_ciphertext)
+    db = zlib.decompress(db_compressed)
+    if db[0:6].upper() == b"SQLITE":
+        with open(output, "wb") as f:
+            f.write(db)
+        return True
+    else:
+        raise ValueError("The plaintext is not a SQLite database. Did you use the key to encrypt something...")
+
+
 def contacts(db, data):
     # Get contacts
     c = db.cursor()