Merge branch 'extract-key' of https://github.com/pkirkovsky/mvt into pkirkovsky-extract-key

mvt/ios/cli.py

@@ -17,6 +17,7 @@ from mvt.common.module import run_module, save_timeline
 from mvt.common.options import MutuallyExclusiveOption
 
 from .decrypt import DecryptBackup
+from .keyutils import KeyUtils
 from .modules.fs import BACKUP_MODULES, FS_MODULES
 
 # Setup logging using Rich.
@@ -62,6 +63,26 @@ def decrypt_backup(destination, password, key_file, backup_path):
         raise click.ClickException("Missing required option. Specify either "
                                    "--password or --key-file.")
 
+#==============================================================================
+# Command: extract-key
+#==============================================================================
+@cli.command("extract-key", help="Extract decryption key from an iTunes backup")
+@click.option("--password", "-p",
+              help="Password to use to decrypt the backup",
+              prompt="Backup password", 
+              hide_input=True, prompt_required=False, required=True)
+@click.option("--key-file", "-k",
+              help="Key file to be written (if unset, will print to STDOUT)",
+              required=False,
+              type=click.Path(exists=False, file_okay=True, dir_okay=False, writable=True))
+@click.argument("BACKUP_PATH", type=click.Path(exists=True))
+def extract_key(password, backup_path, key_file):
+    key_utils = KeyUtils(password, backup_path)
+    if key_file:
+        key_utils.write_key(key_file)
+    else:
+        key_utils.print_key()
+
 
 #==============================================================================
 # Command: check-backup

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 file %s",
+                     self.backup_path, key_file)
+            log.warn("The file %s is equivalent to a plaintext password. Keep this file safe!",
+                     key_file)