Use standard library plistlib over biplist

Since Python 3.4, the standard library has supported the binary
plist format found in iPhone backups, and in 3.8 the support for
UID values was added:
https://docs.python.org/3.8/library/plistlib.html
This is all that is required by this library, so the additional
biplist dependency is now unnecesary.

pyproject.toml

@@ -15,7 +15,6 @@ classifiers = [
 keywords = ["iPhone", "backup", "forensics", "iOS", "WhatsApp", "decryption", "iOS backup", "iTunes Backup"]
 
 dependencies = [
- "biplist>=1.0.3",
  "pycryptodome>=3.20.0"
 ]
 

src/iphone_backup_decrypt/iphone_backup.py

@@ -1,11 +1,10 @@
 import os.path
+import plistlib
 import shutil
 import sqlite3
 import struct
 import tempfile
 
-import biplist
-
 from . import google_iphone_dataprotection
 
 __all__ = ["EncryptedBackup", "RelativePath", "RelativePathsLike", "DomainLike", "MatchFiles"]
@@ -138,7 +137,7 @@ def _read_and_unlock_keybag(self):
  return self._unlocked
  # Open the Manifest.plist file to access the Keybag:
  with open(self._manifest_plist_path, 'rb') as infile:
- self._manifest_plist = biplist.readPlist(infile)
+ self._manifest_plist = plistlib.load(infile)
  self._keybag = google_iphone_dataprotection.Keybag(self._manifest_plist['BackupKeyBag'])
  # Attempt to unlock the Keybag:
  self._unlocked = self._keybag.unlockWithPassphrase(self._passphrase)
@@ -188,8 +187,8 @@ def _decrypt_inner_file(self, *, file_id, file_bplist, if_modified_since=None):
  # Ensure we've already unlocked the Keybag:
  self._read_and_unlock_keybag()
  # Read the plist data and extract file metadata:
- plist = biplist.readPlistFromString(file_bplist)
- file_data = plist['$objects'][plist['$top']['root'].integer]
+ plist = plistlib.loads(file_bplist)
+ file_data = plist['$objects'][plist['$top']['root'].data]
  file_mtime = file_data.get("LastModified")
  # Was the file modified since the time requested?
  if if_modified_since and file_mtime <= if_modified_since:
@@ -199,7 +198,7 @@ def _decrypt_inner_file(self, *, file_id, file_bplist, if_modified_since=None):
  protection_class = file_data['ProtectionClass']
  if "EncryptionKey" not in file_data:
  raise ValueError("Path is not an encrypted file.") # File is not encrypted; either a directory or empty.
- encryption_key = plist['$objects'][file_data['EncryptionKey'].integer]['NS.data'][4:]
+ encryption_key = plist['$objects'][file_data['EncryptionKey'].data]['NS.data'][4:]
  inner_key = self._keybag.unwrapKeyForClass(protection_class, encryption_key)
  # Find the encrypted version of the file on disk and decrypt it:
  filename_in_backup = os.path.join(self._backup_directory, file_id[:2], file_id)