Replace pbkdf2 with bcrypt (#16071)

* Replace pbkdf2 with bcrypt

bcrypt isn't inherently better than pbkdf2, but everything "just works"
out of the box.

  * the hash verification routine now only computes one hash per call
  * a per-user salt is built into the hash as opposed to the current
  global salt
  * bcrypt.checkpw() is immune to timing attacks regardless of input
  * hash strength is a function of real time benchmarks and a
  "difficulty" level, meaning we won't have to ever update the iteration
  count

* WIP: add hash upgrade mechanism

* WIP: clarify decode issue

* remove stale testing code

* Fix test

* Ensure incorrect legacy passwords fail

* Add better invalid legacy password test

* Lint

* Run tests in async scope

tests/auth/providers/test_homeassistant.py

@@ -1,6 +1,7 @@
 """Test the Home Assistant local auth provider."""
 from unittest.mock import Mock
 
+import base64
 import pytest
 
 from homeassistant import data_entry_flow
@@ -132,3 +133,91 @@ async def test_new_users_populate_values(hass, data):
     user = await manager.async_get_or_create_user(credentials)
     assert user.name == 'hello'
     assert user.is_active
+
+
+async def test_new_hashes_are_bcrypt(data, hass):
+    """Test that newly created hashes are using bcrypt."""
+    data.add_auth('newuser', 'newpass')
+    found = None
+    for user in data.users:
+        if user['username'] == 'newuser':
+            found = user
+    assert found is not None
+    user_hash = base64.b64decode(found['password'])
+    assert (user_hash.startswith(b'$2a$')
+            or user_hash.startswith(b'$2b$')
+            or user_hash.startswith(b'$2x$')
+            or user_hash.startswith(b'$2y$'))
+
+
+async def test_pbkdf2_to_bcrypt_hash_upgrade(hass_storage, hass):
+    """Test migrating user from pbkdf2 hash to bcrypt hash."""
+    hass_storage[hass_auth.STORAGE_KEY] = {
+        'version': hass_auth.STORAGE_VERSION,
+        'key': hass_auth.STORAGE_KEY,
+        'data': {
+            'salt': '09c52f0b120eaa7dea5f73f9a9b985f3d493b30a08f3f2945ef613'
+                    '0b08e6a3ea',
+            'users': [
+                {
+                    'password': 'L5PAbehB8LAQI2Ixu+d+PDNJKmljqLnBcYWYw35onC/8D'
+                                'BM1SpvT6A8ZFael5+deCt+s+43J08IcztnguouHSw==',
+                    'username': 'legacyuser'
+                }
+            ]
+        },
+    }
+    data = hass_auth.Data(hass)
+    await data.async_load()
+
+    # verify the correct (pbkdf2) password successfuly authenticates the user
+    await hass.async_add_executor_job(
+        data.validate_login, 'legacyuser', 'beer')
+
+    # ...and that the hashes are now bcrypt hashes
+    user_hash = base64.b64decode(
+        hass_storage[hass_auth.STORAGE_KEY]['data']['users'][0]['password'])
+    assert (user_hash.startswith(b'$2a$')
+            or user_hash.startswith(b'$2b$')
+            or user_hash.startswith(b'$2x$')
+            or user_hash.startswith(b'$2y$'))
+
+
+async def test_pbkdf2_to_bcrypt_hash_upgrade_with_incorrect_pass(hass_storage,
+                                                                 hass):
+    """Test migrating user from pbkdf2 hash to bcrypt hash."""
+    hass_storage[hass_auth.STORAGE_KEY] = {
+        'version': hass_auth.STORAGE_VERSION,
+        'key': hass_auth.STORAGE_KEY,
+        'data': {
+            'salt': '09c52f0b120eaa7dea5f73f9a9b985f3d493b30a08f3f2945ef613'
+                    '0b08e6a3ea',
+            'users': [
+                {
+                    'password': 'L5PAbehB8LAQI2Ixu+d+PDNJKmljqLnBcYWYw35onC/8D'
+                                'BM1SpvT6A8ZFael5+deCt+s+43J08IcztnguouHSw==',
+                    'username': 'legacyuser'
+                }
+            ]
+        },
+    }
+    data = hass_auth.Data(hass)
+    await data.async_load()
+
+    orig_user_hash = base64.b64decode(
+        hass_storage[hass_auth.STORAGE_KEY]['data']['users'][0]['password'])
+
+    # Make sure invalid legacy passwords fail
+    with pytest.raises(hass_auth.InvalidAuth):
+        await hass.async_add_executor_job(
+            data.validate_login, 'legacyuser', 'wine')
+
+    # Make sure we don't change the password/hash when password is incorrect
+    with pytest.raises(hass_auth.InvalidAuth):
+        await hass.async_add_executor_job(
+            data.validate_login, 'legacyuser', 'wine')
+
+    same_user_hash = base64.b64decode(
+        hass_storage[hass_auth.STORAGE_KEY]['data']['users'][0]['password'])
+
+    assert orig_user_hash == same_user_hash