diff --git a/export/progress.md b/export/progress.md
index ca73a3c..bdf8b02 100644
--- a/export/progress.md
+++ b/export/progress.md
@@ -75,9 +75,9 @@
 **Test totali auth:** 34 test (19 schemas + 15 router)
 **Coverage auth:** 98%+
 
-### 🔑 Gestione API Keys (T23-T29) - 0/7 completati
-- [ ] T23: Creare Pydantic schemas per API keys - 🟡 In progress (2026-04-07 16:00)
-- [ ] T24: Implementare POST /api/keys (create)
+### 🔑 Gestione API Keys (T23-T29) - 1/7 completati
+- [x] T23: Creare Pydantic schemas per API keys - ✅ Completato (2026-04-07 16:00, commit: 2e4c1bb)
+- [ ] T24: Implementare POST /api/keys (create) - 🟡 In progress (2026-04-07 16:05)
 - [ ] T25: Implementare GET /api/keys (list)
 - [ ] T26: Implementare PUT /api/keys/{id} (update)
 - [ ] T27: Implementare DELETE /api/keys/{id}
diff --git a/src/openrouter_monitor/main.py b/src/openrouter_monitor/main.py
index 46737bf..ebfa077 100644
--- a/src/openrouter_monitor/main.py
+++ b/src/openrouter_monitor/main.py
@@ -6,6 +6,7 @@ from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
 
 from openrouter_monitor.config import get_settings
+from openrouter_monitor.routers import api_keys
 from openrouter_monitor.routers import auth
 
 settings = get_settings()
@@ -29,6 +30,7 @@ app.add_middleware(
 
 # Include routers
 app.include_router(auth.router, prefix="/api/auth", tags=["authentication"])
+app.include_router(api_keys.router, prefix="/api/keys", tags=["api-keys"])
 
 
 @app.get("/")
diff --git a/src/openrouter_monitor/routers/__init__.py b/src/openrouter_monitor/routers/__init__.py
index da8c8e8..022a6b6 100644
--- a/src/openrouter_monitor/routers/__init__.py
+++ b/src/openrouter_monitor/routers/__init__.py
@@ -1,4 +1,5 @@
 """Routers package for OpenRouter Monitor."""
+from openrouter_monitor.routers import api_keys
 from openrouter_monitor.routers import auth
 
-__all__ = ["auth"]
+__all__ = ["auth", "api_keys"]
diff --git a/src/openrouter_monitor/routers/api_keys.py b/src/openrouter_monitor/routers/api_keys.py
new file mode 100644
index 0000000..de48272
--- /dev/null
+++ b/src/openrouter_monitor/routers/api_keys.py
@@ -0,0 +1,217 @@
+"""API Keys router.
+
+T24-T27: Endpoints for API key management (CRUD operations).
+"""
+from fastapi import APIRouter, Depends, HTTPException, status, Query
+from sqlalchemy.orm import Session
+from sqlalchemy import desc
+from typing import Optional
+
+from openrouter_monitor.config import get_settings
+from openrouter_monitor.database import get_db
+from openrouter_monitor.dependencies import get_current_user
+from openrouter_monitor.models import ApiKey, User
+from openrouter_monitor.schemas import (
+    ApiKeyCreate,
+    ApiKeyUpdate,
+    ApiKeyResponse,
+    ApiKeyListResponse,
+)
+from openrouter_monitor.services.encryption import EncryptionService
+
+router = APIRouter()
+settings = get_settings()
+
+# Maximum number of API keys per user
+MAX_API_KEYS_PER_USER = settings.max_api_keys_per_user
+
+# Initialize encryption service
+encryption_service = EncryptionService(settings.encryption_key)
+
+
+@router.post("", response_model=ApiKeyResponse, status_code=status.HTTP_201_CREATED)
+async def create_api_key(
+    api_key_data: ApiKeyCreate,
+    db: Session = Depends(get_db),
+    current_user: User = Depends(get_current_user)
+):
+    """Create a new API key for the current user.
+    
+    The API key is encrypted using AES-256 before storage.
+    
+    Args:
+        api_key_data: API key creation data (name and key value)
+        db: Database session
+        current_user: Currently authenticated user
+        
+    Returns:
+        ApiKeyResponse with the created key details (excluding the key value)
+        
+    Raises:
+        HTTPException: 400 if user has reached MAX_API_KEYS_PER_USER limit
+        HTTPException: 422 if API key format is invalid (validation handled by Pydantic)
+    """
+    # Check if user has reached the limit
+    existing_keys_count = db.query(ApiKey).filter(
+        ApiKey.user_id == current_user.id
+    ).count()
+    
+    if existing_keys_count >= MAX_API_KEYS_PER_USER:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail=f"Maximum number of API keys ({MAX_API_KEYS_PER_USER}) reached. "
+                   "Please delete an existing key before creating a new one."
+        )
+    
+    # Encrypt the API key before storing
+    encrypted_key = encryption_service.encrypt(api_key_data.key)
+    
+    # Create new API key
+    new_api_key = ApiKey(
+        user_id=current_user.id,
+        name=api_key_data.name,
+        key_encrypted=encrypted_key,
+        is_active=True
+    )
+    
+    db.add(new_api_key)
+    db.commit()
+    db.refresh(new_api_key)
+    
+    return new_api_key
+
+
+@router.get("", response_model=ApiKeyListResponse)
+async def list_api_keys(
+    skip: int = Query(0, ge=0, description="Number of records to skip"),
+    limit: int = Query(10, ge=1, le=100, description="Maximum number of records to return"),
+    db: Session = Depends(get_db),
+    current_user: User = Depends(get_current_user)
+):
+    """List all API keys for the current user.
+    
+    Results are paginated and sorted by creation date (newest first).
+    
+    Args:
+        skip: Number of records to skip for pagination
+        limit: Maximum number of records to return
+        db: Database session
+        current_user: Currently authenticated user
+        
+    Returns:
+        ApiKeyListResponse with items list and total count
+    """
+    # Get total count for pagination
+    total = db.query(ApiKey).filter(
+        ApiKey.user_id == current_user.id
+    ).count()
+    
+    # Get paginated keys, sorted by created_at DESC
+    api_keys = db.query(ApiKey).filter(
+        ApiKey.user_id == current_user.id
+    ).order_by(
+        desc(ApiKey.created_at)
+    ).offset(skip).limit(limit).all()
+    
+    return ApiKeyListResponse(items=api_keys, total=total)
+
+
+@router.put("/{api_key_id}", response_model=ApiKeyResponse)
+async def update_api_key(
+    api_key_id: int,
+    api_key_data: ApiKeyUpdate,
+    db: Session = Depends(get_db),
+    current_user: User = Depends(get_current_user)
+):
+    """Update an existing API key.
+    
+    Only the name and is_active fields can be updated.
+    Users can only update their own API keys.
+    
+    Args:
+        api_key_id: ID of the API key to update
+        api_key_data: API key update data (optional fields)
+        db: Database session
+        current_user: Currently authenticated user
+        
+    Returns:
+        ApiKeyResponse with the updated key details
+        
+    Raises:
+        HTTPException: 404 if API key not found
+        HTTPException: 403 if user doesn't own the key
+    """
+    # Find the API key
+    api_key = db.query(ApiKey).filter(
+        ApiKey.id == api_key_id
+    ).first()
+    
+    if not api_key:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="API key not found"
+        )
+    
+    # Verify ownership
+    if api_key.user_id != current_user.id:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail="You don't have permission to modify this API key"
+        )
+    
+    # Update fields if provided
+    if api_key_data.name is not None:
+        api_key.name = api_key_data.name
+    
+    if api_key_data.is_active is not None:
+        api_key.is_active = api_key_data.is_active
+    
+    db.commit()
+    db.refresh(api_key)
+    
+    return api_key
+
+
+@router.delete("/{api_key_id}", status_code=status.HTTP_204_NO_CONTENT)
+async def delete_api_key(
+    api_key_id: int,
+    db: Session = Depends(get_db),
+    current_user: User = Depends(get_current_user)
+):
+    """Delete an API key.
+    
+    Deleting an API key also cascades to delete all associated usage statistics.
+    Users can only delete their own API keys.
+    
+    Args:
+        api_key_id: ID of the API key to delete
+        db: Database session
+        current_user: Currently authenticated user
+        
+    Raises:
+        HTTPException: 404 if API key not found
+        HTTPException: 403 if user doesn't own the key
+    """
+    # Find the API key
+    api_key = db.query(ApiKey).filter(
+        ApiKey.id == api_key_id
+    ).first()
+    
+    if not api_key:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="API key not found"
+        )
+    
+    # Verify ownership
+    if api_key.user_id != current_user.id:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail="You don't have permission to delete this API key"
+        )
+    
+    # Delete the API key (cascade to usage_stats is handled by SQLAlchemy)
+    db.delete(api_key)
+    db.commit()
+    
+    return None
diff --git a/tests/__pycache__/conftest.cpython-313-pytest-9.0.2.pyc b/tests/__pycache__/conftest.cpython-313-pytest-9.0.2.pyc
index 6c2093e..3d44bbe 100644
Binary files a/tests/__pycache__/conftest.cpython-313-pytest-9.0.2.pyc and b/tests/__pycache__/conftest.cpython-313-pytest-9.0.2.pyc differ
diff --git a/tests/conftest.py b/tests/conftest.py
index c7bade0..0ba54c9 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -48,3 +48,67 @@ def mock_env_vars(monkeypatch):
     monkeypatch.setenv('DATABASE_URL', 'sqlite:///./test.db')
     monkeypatch.setenv('DEBUG', 'true')
     monkeypatch.setenv('LOG_LEVEL', 'DEBUG')
+
+
+@pytest.fixture
+def mock_db():
+    """Create a mock database session for unit tests."""
+    from unittest.mock import MagicMock
+    return MagicMock()
+
+
+@pytest.fixture
+def mock_user():
+    """Create a mock authenticated user for testing."""
+    from unittest.mock import MagicMock
+    user = MagicMock()
+    user.id = 1
+    user.email = "test@example.com"
+    user.is_active = True
+    return user
+
+
+@pytest.fixture
+def mock_encryption_service():
+    """Create a mock encryption service for testing."""
+    from unittest.mock import MagicMock
+    mock = MagicMock()
+    mock.encrypt.return_value = "encrypted_key_value"
+    mock.decrypt.return_value = "sk-or-v1-decrypted"
+    return mock
+
+
+@pytest.fixture
+def client():
+    """Create a test client with fresh database."""
+    from fastapi.testclient import TestClient
+    from sqlalchemy import create_engine
+    from sqlalchemy.orm import sessionmaker
+    from sqlalchemy.pool import StaticPool
+    
+    from openrouter_monitor.database import Base, get_db
+    from openrouter_monitor.main import app
+    
+    # Setup in-memory test database
+    SQLALCHEMY_DATABASE_URL = "sqlite:///:memory:"
+    engine = create_engine(
+        SQLALCHEMY_DATABASE_URL,
+        connect_args={"check_same_thread": False},
+        poolclass=StaticPool,
+    )
+    TestingSessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+    
+    def override_get_db():
+        """Override get_db dependency for testing."""
+        try:
+            db = TestingSessionLocal()
+            yield db
+        finally:
+            db.close()
+    
+    app.dependency_overrides[get_db] = override_get_db
+    
+    Base.metadata.create_all(bind=engine)
+    with TestClient(app) as c:
+        yield c
+    Base.metadata.drop_all(bind=engine)
diff --git a/tests/unit/routers/test_api_keys.py b/tests/unit/routers/test_api_keys.py
new file mode 100644
index 0000000..4fadd62
--- /dev/null
+++ b/tests/unit/routers/test_api_keys.py
@@ -0,0 +1,508 @@
+"""Tests for API Keys router.
+
+T24-T27: Test endpoints for API key CRUD operations.
+"""
+import pytest
+from datetime import datetime, timezone
+from unittest.mock import MagicMock, patch
+
+from fastapi import status
+from fastapi.testclient import TestClient
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+from sqlalchemy.pool import StaticPool
+
+from openrouter_monitor.database import Base, get_db
+from openrouter_monitor.main import app
+from openrouter_monitor.models import User
+
+
+# Setup in-memory test database
+SQLALCHEMY_DATABASE_URL = "sqlite:///:memory:"
+engine = create_engine(
+    SQLALCHEMY_DATABASE_URL,
+    connect_args={"check_same_thread": False},
+    poolclass=StaticPool,
+)
+TestingSessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+
+def override_get_db():
+    """Override get_db dependency for testing."""
+    try:
+        db = TestingSessionLocal()
+        yield db
+    finally:
+        db.close()
+
+
+app.dependency_overrides[get_db] = override_get_db
+
+
+@pytest.fixture(scope="function")
+def client():
+    """Create a test client with fresh database."""
+    Base.metadata.create_all(bind=engine)
+    with TestClient(app) as c:
+        yield c
+    Base.metadata.drop_all(bind=engine)
+
+
+@pytest.fixture
+def test_user(client):
+    """Create a test user and return user data."""
+    user_data = {
+        "email": "test@example.com",
+        "password": "SecurePass123!",
+        "password_confirm": "SecurePass123!"
+    }
+    response = client.post("/api/auth/register", json=user_data)
+    assert response.status_code == 201
+    return user_data
+
+
+@pytest.fixture
+def auth_token(client, test_user):
+    """Get auth token for test user."""
+    login_data = {
+        "email": test_user["email"],
+        "password": test_user["password"]
+    }
+    response = client.post("/api/auth/login", json=login_data)
+    assert response.status_code == 200
+    return response.json()["access_token"]
+
+
+@pytest.fixture
+def authorized_client(client, auth_token):
+    """Create a client with authorization header."""
+    client.headers = {"Authorization": f"Bearer {auth_token}"}
+    return client
+
+
+@pytest.fixture
+def another_test_user(client):
+    """Create another test user for security tests."""
+    user_data = {
+        "email": "user2@example.com",
+        "password": "SecurePass123!",
+        "password_confirm": "SecurePass123!"
+    }
+    response = client.post("/api/auth/register", json=user_data)
+    assert response.status_code == 201
+    return user_data
+
+
+@pytest.fixture
+def another_auth_token(client, another_test_user):
+    """Get auth token for the second test user."""
+    login_data = {
+        "email": another_test_user["email"],
+        "password": another_test_user["password"]
+    }
+    response = client.post("/api/auth/login", json=login_data)
+    assert response.status_code == 200
+    return response.json()["access_token"]
+
+
+class TestCreateApiKey:
+    """Tests for POST /api/keys endpoint (T24)."""
+
+    def test_create_api_key_success(self, authorized_client):
+        """Test successful API key creation."""
+        response = authorized_client.post(
+            "/api/keys",
+            json={
+                "name": "Production Key",
+                "key": "sk-or-v1-abc123def456ghi789jkl012mno345pqr678stu901vwx234yz"
+            }
+        )
+        
+        assert response.status_code == status.HTTP_201_CREATED
+        data = response.json()
+        assert data["name"] == "Production Key"
+        assert data["is_active"] is True
+        assert "id" in data
+        assert "created_at" in data
+        # Verify key is NOT returned in response
+        assert "key" not in data
+        assert "key_encrypted" not in data
+
+    def test_create_api_key_limit_reached(self, authorized_client, monkeypatch):
+        """Test that creating more than MAX_API_KEYS_PER_USER returns 400."""
+        from openrouter_monitor import routers
+        # Set limit to 1 to make test easier
+        monkeypatch.setattr(routers.api_keys, "MAX_API_KEYS_PER_USER", 1)
+        
+        # Create first key (should succeed)
+        response1 = authorized_client.post(
+            "/api/keys",
+            json={"name": "Key 1", "key": "sk-or-v1-key1"}
+        )
+        assert response1.status_code == status.HTTP_201_CREATED
+        
+        # Try to create second key (should fail due to limit)
+        response2 = authorized_client.post(
+            "/api/keys",
+            json={"name": "Key 2", "key": "sk-or-v1-key2"}
+        )
+        
+        assert response2.status_code == status.HTTP_400_BAD_REQUEST
+        assert "maximum" in response2.json()["detail"].lower()
+
+    def test_create_api_key_invalid_format(self, authorized_client):
+        """Test that invalid key format returns 422 validation error."""
+        response = authorized_client.post(
+            "/api/keys",
+            json={
+                "name": "Test Key",
+                "key": "invalid-key-format"  # Missing sk-or-v1- prefix
+            }
+        )
+        
+        assert response.status_code == status.HTTP_422_UNPROCESSABLE_ENTITY
+
+    def test_create_api_key_unauthorized(self, client):
+        """Test that request without auth returns 401."""
+        response = client.post(
+            "/api/keys",
+            json={
+                "name": "Test Key",
+                "key": "sk-or-v1-abc123"
+            }
+        )
+        
+        assert response.status_code == status.HTTP_401_UNAUTHORIZED
+
+    def test_create_api_key_empty_name(self, authorized_client):
+        """Test that empty name returns 422 validation error."""
+        response = authorized_client.post(
+            "/api/keys",
+            json={
+                "name": "",
+                "key": "sk-or-v1-abc123"
+            }
+        )
+        
+        assert response.status_code == status.HTTP_422_UNPROCESSABLE_ENTITY
+
+    def test_create_api_key_name_too_long(self, authorized_client):
+        """Test that name > 100 chars returns 422 validation error."""
+        response = authorized_client.post(
+            "/api/keys",
+            json={
+                "name": "x" * 101,
+                "key": "sk-or-v1-abc123"
+            }
+        )
+        
+        assert response.status_code == status.HTTP_422_UNPROCESSABLE_ENTITY
+
+
+class TestListApiKeys:
+    """Tests for GET /api/keys endpoint (T25)."""
+
+    def test_list_api_keys_empty(self, authorized_client):
+        """Test listing keys when user has no keys."""
+        response = authorized_client.get("/api/keys")
+        
+        assert response.status_code == status.HTTP_200_OK
+        data = response.json()
+        assert data["items"] == []
+        assert data["total"] == 0
+
+    def test_list_api_keys_with_data(self, authorized_client):
+        """Test listing keys with existing data."""
+        # Create some keys
+        for i in range(3):
+            authorized_client.post(
+                "/api/keys",
+                json={"name": f"Key {i}", "key": f"sk-or-v1-key{i}"}
+            )
+        
+        response = authorized_client.get("/api/keys")
+        
+        assert response.status_code == status.HTTP_200_OK
+        data = response.json()
+        assert data["total"] == 3
+        assert len(data["items"]) == 3
+        # Check ordering (newest first)
+        assert data["items"][0]["name"] == "Key 2"
+        assert data["items"][2]["name"] == "Key 0"
+
+    def test_list_api_keys_pagination(self, authorized_client):
+        """Test pagination with skip and limit."""
+        # Create 5 keys
+        for i in range(5):
+            authorized_client.post(
+                "/api/keys",
+                json={"name": f"Key {i}", "key": f"sk-or-v1-key{i}"}
+            )
+        
+        # Test skip=2, limit=2
+        response = authorized_client.get("/api/keys?skip=2&limit=2")
+        
+        assert response.status_code == status.HTTP_200_OK
+        data = response.json()
+        assert data["total"] == 5
+        assert len(data["items"]) == 2
+        # Due to DESC ordering, skip=2 means we get keys 2 and 1
+
+    def test_list_api_keys_unauthorized(self, client):
+        """Test that request without auth returns 401."""
+        response = client.get("/api/keys")
+        
+        assert response.status_code == status.HTTP_401_UNAUTHORIZED
+
+
+class TestUpdateApiKey:
+    """Tests for PUT /api/keys/{id} endpoint (T26)."""
+
+    def test_update_api_key_success(self, authorized_client):
+        """Test successful API key update."""
+        # Create a key first
+        create_response = authorized_client.post(
+            "/api/keys",
+            json={"name": "Old Name", "key": "sk-or-v1-abc123"}
+        )
+        key_id = create_response.json()["id"]
+        
+        # Update the key
+        response = authorized_client.put(
+            f"/api/keys/{key_id}",
+            json={"name": "Updated Name", "is_active": False}
+        )
+        
+        assert response.status_code == status.HTTP_200_OK
+        data = response.json()
+        assert data["name"] == "Updated Name"
+        assert data["is_active"] is False
+
+    def test_update_api_key_partial_name_only(self, authorized_client):
+        """Test update with name only."""
+        # Create a key
+        create_response = authorized_client.post(
+            "/api/keys",
+            json={"name": "Old Name", "key": "sk-or-v1-abc123"}
+        )
+        key_id = create_response.json()["id"]
+        
+        # Update name only
+        response = authorized_client.put(
+            f"/api/keys/{key_id}",
+            json={"name": "New Name"}
+        )
+        
+        assert response.status_code == status.HTTP_200_OK
+        data = response.json()
+        assert data["name"] == "New Name"
+        assert data["is_active"] is True  # Unchanged
+
+    def test_update_api_key_partial_is_active_only(self, authorized_client):
+        """Test update with is_active only."""
+        # Create a key
+        create_response = authorized_client.post(
+            "/api/keys",
+            json={"name": "Key Name", "key": "sk-or-v1-abc123"}
+        )
+        key_id = create_response.json()["id"]
+        
+        # Update is_active only
+        response = authorized_client.put(
+            f"/api/keys/{key_id}",
+            json={"is_active": False}
+        )
+        
+        assert response.status_code == status.HTTP_200_OK
+
+    def test_update_api_key_not_found(self, authorized_client):
+        """Test update for non-existent key returns 404."""
+        response = authorized_client.put(
+            "/api/keys/999",
+            json={"name": "New Name"}
+        )
+        
+        assert response.status_code == status.HTTP_404_NOT_FOUND
+
+    def test_update_api_key_not_owner(self, client, another_auth_token):
+        """Test update of another user's key returns 403."""
+        # This test requires creating a key with one user and trying to update with another
+        # For simplicity, we just check that the endpoint enforces ownership
+        # The actual test would need two authenticated clients
+        
+        # For now, just verify 403 is returned for non-existent key with wrong user context
+        client.headers = {"Authorization": f"Bearer {another_auth_token}"}
+        response = client.put(
+            "/api/keys/1",
+            json={"name": "New Name"}
+        )
+        
+        # Should return 404 (not found) since key 1 doesn't exist for this user
+        # or 403 if we found a key owned by someone else
+        assert response.status_code in [status.HTTP_404_NOT_FOUND, status.HTTP_403_FORBIDDEN]
+
+    def test_update_api_key_unauthorized(self, client):
+        """Test that request without auth returns 401."""
+        response = client.put(
+            "/api/keys/1",
+            json={"name": "New Name"}
+        )
+        
+        assert response.status_code == status.HTTP_401_UNAUTHORIZED
+
+
+class TestDeleteApiKey:
+    """Tests for DELETE /api/keys/{id} endpoint (T27)."""
+
+    def test_delete_api_key_success(self, authorized_client):
+        """Test successful API key deletion."""
+        # Create a key
+        create_response = authorized_client.post(
+            "/api/keys",
+            json={"name": "Key to Delete", "key": "sk-or-v1-abc123"}
+        )
+        key_id = create_response.json()["id"]
+        
+        # Delete the key
+        response = authorized_client.delete(f"/api/keys/{key_id}")
+        
+        assert response.status_code == status.HTTP_204_NO_CONTENT
+        
+        # Verify it's deleted
+        list_response = authorized_client.get("/api/keys")
+        assert list_response.json()["total"] == 0
+
+    def test_delete_api_key_not_found(self, authorized_client):
+        """Test deletion of non-existent key returns 404."""
+        response = authorized_client.delete("/api/keys/999")
+        
+        assert response.status_code == status.HTTP_404_NOT_FOUND
+
+    def test_delete_api_key_not_owner(self, client, another_auth_token):
+        """Test deletion of another user's key returns 403."""
+        client.headers = {"Authorization": f"Bearer {another_auth_token}"}
+        response = client.delete("/api/keys/1")
+        
+        assert response.status_code in [status.HTTP_404_NOT_FOUND, status.HTTP_403_FORBIDDEN]
+
+    def test_delete_api_key_unauthorized(self, client):
+        """Test that request without auth returns 401."""
+        response = client.delete("/api/keys/1")
+        
+        assert response.status_code == status.HTTP_401_UNAUTHORIZED
+
+
+class TestSecurity:
+    """Security tests for API keys endpoints."""
+
+    def test_user_a_cannot_see_user_b_keys(self, client, authorized_client, another_auth_token):
+        """Test that user A cannot see user B's keys."""
+        # User A creates a key
+        authorized_client.post(
+            "/api/keys",
+            json={"name": "User A Key", "key": "sk-or-v1-usera"}
+        )
+        
+        # User B tries to list keys
+        client.headers = {"Authorization": f"Bearer {another_auth_token}"}
+        response = client.get("/api/keys")
+        
+        assert response.status_code == status.HTTP_200_OK
+        data = response.json()
+        # User B should see empty list
+        assert data["items"] == []
+        assert data["total"] == 0
+
+    def test_user_a_cannot_modify_user_b_keys(self, client, authorized_client, another_auth_token):
+        """Test that user A cannot modify user B's keys."""
+        # User A creates a key
+        create_response = authorized_client.post(
+            "/api/keys",
+            json={"name": "User A Key", "key": "sk-or-v1-usera"}
+        )
+        key_id = create_response.json()["id"]
+        
+        # User B tries to modify the key
+        client.headers = {"Authorization": f"Bearer {another_auth_token}"}
+        response = client.put(
+            f"/api/keys/{key_id}",
+            json={"name": "Hacked Name"}
+        )
+        
+        # Should return 404 (not found for user B) or 403 (forbidden)
+        assert response.status_code in [status.HTTP_404_NOT_FOUND, status.HTTP_403_FORBIDDEN]
+
+    def test_user_a_cannot_delete_user_b_keys(self, client, authorized_client, another_auth_token):
+        """Test that user A cannot delete user B's keys."""
+        # User A creates a key
+        create_response = authorized_client.post(
+            "/api/keys",
+            json={"name": "User A Key", "key": "sk-or-v1-usera"}
+        )
+        key_id = create_response.json()["id"]
+        
+        # User B tries to delete the key
+        client.headers = {"Authorization": f"Bearer {another_auth_token}"}
+        response = client.delete(f"/api/keys/{key_id}")
+        
+        # Should return 404 (not found for user B) or 403 (forbidden)
+        assert response.status_code in [status.HTTP_404_NOT_FOUND, status.HTTP_403_FORBIDDEN]
+
+    def test_key_never_exposed_in_response(self, authorized_client):
+        """Test that API key value is never exposed in any response."""
+        # Create a key
+        create_response = authorized_client.post(
+            "/api/keys",
+            json={"name": "Test Key", "key": "sk-or-v1-secret-value"}
+        )
+        
+        # Verify create response doesn't contain key
+        create_data = create_response.json()
+        assert "key" not in create_data
+        assert "key_encrypted" not in create_data
+        
+        # List keys
+        list_response = authorized_client.get("/api/keys")
+        list_data = list_response.json()
+        
+        for item in list_data["items"]:
+            assert "key" not in item
+            assert "key_encrypted" not in item
+        
+        # Update key
+        key_id = create_data["id"]
+        update_response = authorized_client.put(
+            f"/api/keys/{key_id}",
+            json={"name": "Updated"}
+        )
+        update_data = update_response.json()
+        
+        assert "key" not in update_data
+        assert "key_encrypted" not in update_data
+
+    def test_api_key_is_encrypted_in_database(self, authorized_client):
+        """Test that API key is encrypted before storage in database."""
+        from openrouter_monitor.models import ApiKey
+        
+        # Create a key
+        api_key_value = "sk-or-v1-test-encryption-key"
+        create_response = authorized_client.post(
+            "/api/keys",
+            json={"name": "Test Encryption", "key": api_key_value}
+        )
+        
+        assert create_response.status_code == status.HTTP_201_CREATED
+        key_id = create_response.json()["id"]
+        
+        # Check database - key should be encrypted
+        # Access the database through the TestingSessionLocal used in tests
+        db = TestingSessionLocal()
+        try:
+            api_key = db.query(ApiKey).filter(ApiKey.id == key_id).first()
+            assert api_key is not None
+            # The encrypted key should not be the plaintext value
+            assert api_key.key_encrypted != api_key_value
+            # The encrypted key should not contain the plaintext prefix
+            assert "sk-or-v1-" not in api_key.key_encrypted
+        finally:
+            db.close()