From dacbde7d774716a095877f727c4fb050c4784171 Mon Sep 17 00:00:00 2001
From: Pascal Vizeli <pascal.vizeli@syshack.ch>
Date: Sun, 18 Feb 2018 10:57:05 +0100
Subject: [PATCH] Extend the security of snapshots (#367)

* extend security

* fix lint
---
 hassio/snapshots/snapshot.py |  8 +++++---
 hassio/snapshots/utils.py    | 11 +++++++++--
 hassio/utils/tar.py          | 18 ++++++++++++++----
 3 files changed, 28 insertions(+), 9 deletions(-)

diff --git a/hassio/snapshots/snapshot.py b/hassio/snapshots/snapshot.py
index da3019553..0ee11a6f6 100644
--- a/hassio/snapshots/snapshot.py
+++ b/hassio/snapshots/snapshot.py
@@ -13,7 +13,8 @@ import voluptuous as vol
 from voluptuous.humanize import humanize_error
 
 from .validate import SCHEMA_SNAPSHOT, ALL_FOLDERS
-from .utils import remove_folder, password_to_key, password_for_validating
+from .utils import (
+    remove_folder, password_to_key, password_for_validating, key_to_iv)
 from ..const import (
     ATTR_SLUG, ATTR_NAME, ATTR_DATE, ATTR_ADDONS, ATTR_REPOSITORIES,
     ATTR_HOMEASSISTANT, ATTR_FOLDERS, ATTR_VERSION, ATTR_TYPE, ATTR_IMAGE,
@@ -130,7 +131,8 @@ class Snapshot(CoreSysAttributes):
         # Set password
         if password:
             self._key = password_to_key(password)
-            self._aes = AES.new(self._key, AES.MODE_ECB)
+            self._aes = AES.new(
+                self._key, AES.MODE_CBC, iv=key_to_iv(self._key))
             self._data[ATTR_PROTECTED] = password_for_validating(password)
             self._data[ATTR_CRYPTO] = CRYPTO_AES128
 
@@ -144,7 +146,7 @@ class Snapshot(CoreSysAttributes):
             return False
 
         self._key = password_to_key(password)
-        self._aes = AES.new(self._key, AES.MODE_ECB)
+        self._aes = AES.new(self._key, AES.MODE_CBC, iv=key_to_iv(self._key))
         return True
 
     def _encrypt_data(self, data):
diff --git a/hassio/snapshots/utils.py b/hassio/snapshots/utils.py
index 64b334f57..64b15185d 100644
--- a/hassio/snapshots/utils.py
+++ b/hassio/snapshots/utils.py
@@ -4,7 +4,7 @@ import shutil
 
 
 def password_to_key(password):
-    """Generate a AES Key from password"""
+    """Generate a AES Key from password."""
     password = password.encode()
     for _ in range(100):
         password = hashlib.sha256(password).digest()
@@ -12,12 +12,19 @@ def password_to_key(password):
 
 
 def password_for_validating(password):
-    """Generate a SHA256 hash from password"""
+    """Generate a SHA256 hash from password."""
     for _ in range(100):
         password = hashlib.sha256(password.encode()).hexdigest()
     return password
 
 
+def key_to_iv(key):
+    """Generate a iv from Key."""
+    for _ in range(100):
+        key = hashlib.sha256(key).digest()
+    return key[:16]
+
+
 def create_slug(name, date_str):
     """Generate a hash from repository."""
     key = "{} - {}".format(date_str, name).lower().encode()
diff --git a/hassio/utils/tar.py b/hassio/utils/tar.py
index 60c139293..a1f23537c 100644
--- a/hassio/utils/tar.py
+++ b/hassio/utils/tar.py
@@ -1,5 +1,6 @@
 """Tarfile fileobject handler for encrypted files."""
 import tarfile
+import hashlib
 
 from Crypto.Cipher import AES
 from Crypto.Random import get_random_bytes
@@ -39,11 +40,12 @@ class SecureTarFile(object):
 
         # Extract IV for CBC
         if self._mode == MOD_READ:
-            cbc_iv = self._file.read(16)
+            cbc_rand = self._file.read(16)
         else:
-            cbc_iv = get_random_bytes(16)
-            self._file.write(cbc_iv)
-        self._aes = AES.new(self._key, AES.MODE_CBC, iv=cbc_iv)
+            cbc_rand = get_random_bytes(16)
+            self._file.write(cbc_rand)
+        self._aes = AES.new(
+            self._key, AES.MODE_CBC, iv=_generate_iv(self._key, cbc_rand))
 
         self._tar = tarfile.open(fileobj=self, mode=self._tar_mode)
         return self._tar
@@ -76,3 +78,11 @@ class SecureTarFile(object):
         if not self._name.is_file():
             return 0
         return round(self._name.stat().st_size / 1048576, 2)  # calc mbyte
+
+
+def _generate_iv(key, salt):
+    """Generate a iv from data."""
+    temp_iv = key + salt
+    for _ in range(100):
+        temp_iv = hashlib.sha256(temp_iv).digest()
+    return temp_iv[:16]