KeyUtils class for working with decryption keys

mvt/ios/keyutils.py

@@ -0,0 +1,52 @@
+import os
+import logging
+from iOSbackup import iOSbackup
+
+log = logging.getLogger(__name__)
+
+class KeyUtils:
+    """This class provides functions to extract a backup key from a password.
+    """
+
+    def __init__(self, password, backup_path):
+        """Generates a key file for an iOS backup.
+        :param password: Backup encryption password
+        :param key_file: Path to the file where to store the generated key file
+        """
+        self.password = password
+        self.backup_path = backup_path
+        self._backup = None
+
+    def get_key(self):
+        try:
+            self._backup = iOSbackup(udid=os.path.basename(self.backup_path),
+                                     cleartextpassword=self.password,
+                                     backuproot=os.path.dirname(self.backup_path))
+        except Exception as e:
+            log.exception(e)
+            log.critical("Failed to decrypt backup. Did you provide the correct password?")
+            return
+        else:
+            self.decryption_key = self._backup.getDecryptionKey()
+            log.info("Extracted decryption key.")
+
+    def print_key(self):
+        self.get_key()
+        log.info("Decryption key for backup at path %s is:\n %s",
+                 self.backup_path, self.decryption_key)
+    
+    def write_key(self, key_file):
+        self.get_key()
+        
+        try:
+            with open(key_file, 'w') as writer:
+                writer.write(self.decryption_key)
+        except Exception as e:
+            log.exception(e)
+            log.critical("Failed to write key file.")
+            return
+        else:
+            log.info("Wrote decryption key for backup at path %s to %s",
+                     self.backup_path, key_file)
+            log.warn("%s is equivalent to a stored plaintext password. Keep this file safe!",
+                     key_file)