diff --git a/auth/utils.py b/auth/utils.py
index 4bded89..69f0b8d 100644
--- a/auth/utils.py
+++ b/auth/utils.py
@@ -1,14 +1,19 @@
-import bcrypt
-import jwt
+import logging
 import os
 import secrets
 from datetime import datetime, timedelta
 from functools import wraps
-from flask import request, jsonify, g
+from typing import Optional, Tuple
+
+import bcrypt
+import jwt
+from flask import g, jsonify, request
 from flask_jwt_extended import get_jwt_identity, verify_jwt_in_request
+
 from cache_db.redis_client import redis_client
-from cache_db.models import User, RefreshToken
-from typing import Tuple, Optional
+from cache_db.models import User
+
+logger = logging.getLogger(__name__)
 
 
 class PasswordUtils:
@@ -129,7 +134,9 @@ def decorated_function(*args, **kwargs):
             g.user = user_data
             return f(*args, **kwargs)
         except Exception as e:
-            return jsonify({'error': 'Unauthorized', 'details': str(e)}), 401
+            # Security: do not leak internal exception details to unauthenticated callers
+            logger.error("Authentication failed: %s", e)
+            return jsonify({'error': 'Unauthorized'}), 401
     return decorated_function
 
 
diff --git a/src/handoff/__init__.py b/src/handoff/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/test_auth_utils.py b/tests/test_auth_utils.py
new file mode 100644
index 0000000..41632d8
--- /dev/null
+++ b/tests/test_auth_utils.py
@@ -0,0 +1,59 @@
+import sys
+from unittest.mock import MagicMock
+
+# Mock cache_db module dependencies before importing auth.utils
+cache_db_mock = MagicMock()
+redis_client_mock = MagicMock()
+models_mock = MagicMock()
+cache_db_mock.redis_client = redis_client_mock
+cache_db_mock.models = models_mock
+
+sys.modules["cache_db"] = cache_db_mock
+sys.modules["cache_db.redis_client"] = redis_client_mock
+sys.modules["cache_db.models"] = models_mock
+
+import pytest
+from flask import Flask
+from auth.utils import PasswordUtils, JWTUtils, login_required
+
+
+def test_password_utils():
+    hashed = PasswordUtils.hash_password("password123")
+    assert PasswordUtils.verify_password("password123", hashed) is True
+    assert PasswordUtils.verify_password("wrongpassword", hashed) is False
+
+    with pytest.raises(ValueError):
+        PasswordUtils.hash_password("short")
+
+
+def test_jwt_utils():
+    access, refresh = JWTUtils.create_tokens("user1", "alice")
+    decoded_access = JWTUtils.decode_token(access)
+    assert decoded_access["user_id"] == "user1"
+    assert decoded_access["username"] == "alice"
+    assert decoded_access["type"] == "access"
+
+    assert JWTUtils.decode_token("invalid.token.here") is None
+
+
+def test_login_required_sanitizes_errors(monkeypatch):
+    app = Flask(__name__)
+
+    @app.route("/protected")
+    @login_required
+    def protected():
+        return "ok"
+
+    client = app.test_client()
+
+    # Force verify_jwt_in_request to raise an exception with sensitive internal details
+    def mock_verify():
+        raise Exception("Sensitive DB connection error or stack info")
+
+    monkeypatch.setattr("auth.utils.verify_jwt_in_request", mock_verify)
+
+    response = client.get("/protected")
+    assert response.status_code == 401
+    data = response.get_json()
+    assert data == {"error": "Unauthorized"}
+    assert "details" not in data