diff --git a/docker/auth/auth.py b/docker/auth/auth.py
index 2ed894ee..416dd7c4 100644
--- a/docker/auth/auth.py
+++ b/docker/auth/auth.py
@@ -96,7 +96,7 @@ def decode_auth(auth):
         auth = auth.encode('ascii')
     s = base64.b64decode(auth)
     login, pwd = s.split(b':', 1)
-    return login.decode('ascii'), pwd.decode('ascii')
+    return login.decode('utf8'), pwd.decode('utf8')
 
 
 def encode_header(auth):

decode_auth function does not handle utf-8 logins or password
HI

I have found that the function **decode_auth** (line 96, [file](https://github.com/docker/docker-py/blob/master/docker/auth/auth.py)) fails when decoding UTF-8 passwords from the .dockercfg file, and **load_config** returning an empty config.

I have checked and docker hub can handle UTF-8 passwords, this code proves that:
```python
# coding=utf-8
from docker import Client
cred = { 'username': <user>, 'password': <utf-8 password> }
c = Client(base_url='unix://var/run/docker.sock')
res = c.pull(repository='<private container>', tag='latest', auth_config=cred)
print(res)
```

Thank you
diff --git a/tests/unit/auth_test.py b/tests/unit/auth_test.py
index 9f4d439b..67830381 100644
--- a/tests/unit/auth_test.py
+++ b/tests/unit/auth_test.py
@@ -316,3 +316,33 @@ class LoadConfigTest(base.Cleanup, base.BaseTestCase):
             self.assertEqual(cfg['password'], 'izayoi')
             self.assertEqual(cfg['email'], 'sakuya@scarlet.net')
             self.assertEqual(cfg.get('auth'), None)
+
+    def test_load_config_custom_config_env_utf8(self):
+        folder = tempfile.mkdtemp()
+        self.addCleanup(shutil.rmtree, folder)
+
+        dockercfg_path = os.path.join(folder, 'config.json')
+        registry = 'https://your.private.registry.io'
+        auth_ = base64.b64encode(
+            b'sakuya\xc3\xa6:izayoi\xc3\xa6').decode('ascii')
+        config = {
+            'auths': {
+                registry: {
+                    'auth': '{0}'.format(auth_),
+                    'email': 'sakuya@scarlet.net'
+                }
+            }
+        }
+
+        with open(dockercfg_path, 'w') as f:
+            json.dump(config, f)
+
+        with mock.patch.dict(os.environ, {'DOCKER_CONFIG': folder}):
+            cfg = auth.load_config(None)
+            assert registry in cfg
+            self.assertNotEqual(cfg[registry], None)
+            cfg = cfg[registry]
+            self.assertEqual(cfg['username'], b'sakuya\xc3\xa6'.decode('utf8'))
+            self.assertEqual(cfg['password'], b'izayoi\xc3\xa6'.decode('utf8'))
+            self.assertEqual(cfg['email'], 'sakuya@scarlet.net')
+            self.assertEqual(cfg.get('auth'), None)

pip install -e .
parse_log_pytest
requirements.txt
pytest pytest-cov pytest-xdist pytest-mock
apt-get update apt-get install -y gcc
3.7
requirements.txt
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
certifi @ file:///croot/certifi_1671487769961/work/certifi
coverage==7.2.7
-e git+https://github.com/docker/docker-py.git@47ab89ec2bd3bddf1221b856ffbaff333edeabb4#egg=docker_py
exceptiongroup==1.2.2
execnet==2.0.2
importlib-metadata==6.7.0
iniconfig==2.0.0
packaging==24.0
pluggy==1.2.0
pytest==7.4.4
pytest-cov==4.1.0
pytest-mock==3.11.1
pytest-xdist==3.5.0
requests==2.5.3
six==1.17.0
tomli==2.0.1
typing_extensions==4.7.1
websocket-client==0.32.0
zipp==3.15.0

name: docker-py
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - ca-certificates=2025.2.25=h06a4308_0
  - certifi=2022.12.7=py37h06a4308_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.4.4=h6a678d5_1
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - ncurses=6.4=h6a678d5_0
  - openssl=1.1.1w=h7f8727e_0
  - pip=22.3.1=py37h06a4308_0
  - python=3.7.16=h7a1cb2a_0
  - readline=8.2=h5eee18b_0
  - setuptools=65.6.3=py37h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - wheel=0.38.4=py37h06a4308_0
  - xz=5.6.4=h5eee18b_1
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - coverage==7.2.7
      - exceptiongroup==1.2.2
      - execnet==2.0.2
      - importlib-metadata==6.7.0
      - iniconfig==2.0.0
      - packaging==24.0
      - pluggy==1.2.0
      - pytest==7.4.4
      - pytest-cov==4.1.0
      - pytest-mock==3.11.1
      - pytest-xdist==3.5.0
      - requests==2.5.3
      - six==1.17.0
      - tomli==2.0.1
      - typing-extensions==4.7.1
      - websocket-client==0.32.0
      - zipp==3.15.0
prefix: /opt/conda/envs/docker-py

tests/unit/auth_test.py::LoadConfigTest::test_load_config_custom_config_env_utf8
tests/unit/auth_test.py::RegressionTest::test_803_urlsafe_encode tests/unit/auth_test.py::ResolveAuthTest::test_resolve_authconfig_default_explicit_none tests/unit/auth_test.py::ResolveAuthTest::test_resolve_authconfig_default_registry tests/unit/auth_test.py::ResolveAuthTest::test_resolve_authconfig_fully_explicit tests/unit/auth_test.py::ResolveAuthTest::test_resolve_authconfig_hostname_only tests/unit/auth_test.py::ResolveAuthTest::test_resolve_authconfig_legacy_config tests/unit/auth_test.py::ResolveAuthTest::test_resolve_authconfig_no_match tests/unit/auth_test.py::ResolveAuthTest::test_resolve_authconfig_no_path tests/unit/auth_test.py::ResolveAuthTest::test_resolve_authconfig_no_path_trailing_slash tests/unit/auth_test.py::ResolveAuthTest::test_resolve_authconfig_no_path_wrong_insecure_proto tests/unit/auth_test.py::ResolveAuthTest::test_resolve_authconfig_no_path_wrong_secure_proto tests/unit/auth_test.py::ResolveAuthTest::test_resolve_authconfig_no_protocol tests/unit/auth_test.py::ResolveAuthTest::test_resolve_authconfig_path_wrong_proto tests/unit/auth_test.py::ResolveAuthTest::test_resolve_registry_and_auth_hub_image tests/unit/auth_test.py::ResolveAuthTest::test_resolve_registry_and_auth_library_image tests/unit/auth_test.py::ResolveAuthTest::test_resolve_registry_and_auth_private_registry tests/unit/auth_test.py::ResolveAuthTest::test_resolve_registry_and_auth_unauthenticated_registry tests/unit/auth_test.py::ResolveAuthTest::test_resolve_repository_name_hub_image tests/unit/auth_test.py::ResolveAuthTest::test_resolve_repository_name_hub_library_image tests/unit/auth_test.py::ResolveAuthTest::test_resolve_repository_name_localhost tests/unit/auth_test.py::ResolveAuthTest::test_resolve_repository_name_localhost_with_username tests/unit/auth_test.py::ResolveAuthTest::test_resolve_repository_name_no_dots_but_port tests/unit/auth_test.py::ResolveAuthTest::test_resolve_repository_name_no_dots_but_port_and_username tests/unit/auth_test.py::ResolveAuthTest::test_resolve_repository_name_private_registry tests/unit/auth_test.py::ResolveAuthTest::test_resolve_repository_name_private_registry_with_port tests/unit/auth_test.py::ResolveAuthTest::test_resolve_repository_name_private_registry_with_username tests/unit/auth_test.py::LoadConfigTest::test_load_config tests/unit/auth_test.py::LoadConfigTest::test_load_config_custom_config_env tests/unit/auth_test.py::LoadConfigTest::test_load_config_custom_config_env_with_auths tests/unit/auth_test.py::LoadConfigTest::test_load_config_no_file tests/unit/auth_test.py::LoadConfigTest::test_load_config_with_random_name
docker/auth/auth.py
docker/auth/auth.py