diff --git a/frontend/src/components/drawer/PasskeyModal.tsx b/frontend/src/components/drawer/PasskeyModal.tsx
index 97940d9..bf1b5ad 100644
--- a/frontend/src/components/drawer/PasskeyModal.tsx
+++ b/frontend/src/components/drawer/PasskeyModal.tsx
@@ -1,26 +1,26 @@
-import { LockKeyIcon } from "@phosphor-icons/react";
+import { HourglassSimpleMediumIcon } from "@phosphor-icons/react";
+import { useAuth } from "../../hooks/useAuth";
 import { Modal } from "../ui/Modal";
 
-interface PasskeyModalProps {
-  onUnlock: (password: string) => Promise<void>;
-}
+export function PasskeyModal() {
+  const { unlock } = useAuth();
 
-export function PasskeyModal({ onUnlock }: PasskeyModalProps) {
   return (
     <Modal isOpen={true}>
-      <LockKeyIcon
+      <HourglassSimpleMediumIcon
         size={48}
         className="text-primary mx-auto mb-8 animate-pulse"
+        weight="duotone"
       />
       <h3 className="font-bold text-lg font-display text-primary">
-        Authentication Required
+        You've been away a while.
       </h3>
       <p className="py-4 font-sans">
-        We need your passkey to open your letters
+        Your letters are still there. Just need the key once more.
       </p>
       <div className="divider w-1/2 mx-auto text-xs text-neutral-content/30 mt-0"></div>
       <p className="text-xs text-neutral-content/30 font-mono italic">
-        Your passkey is used to decrypt your data locally.
+        Nothing was lost.
       </p>
       <div className="modal-action items-center gap-4">
         <form
@@ -30,7 +30,7 @@ export function PasskeyModal({ onUnlock }: PasskeyModalProps) {
             const formData = new FormData(e.currentTarget);
             const password = formData.get("password") as string;
             if (!password) return;
-            await onUnlock(password);
+            await unlock(password);
           }}
         >
           <input
diff --git a/frontend/src/hooks/useAuth.test.ts b/frontend/src/hooks/useAuth.test.ts
index c6d0f43..425e994 100644
--- a/frontend/src/hooks/useAuth.test.ts
+++ b/frontend/src/hooks/useAuth.test.ts
@@ -6,6 +6,7 @@ import { mockUser } from "../../test/fixtures/user.fixture";
 import { server } from "../../test/mocks/server";
 import { useAuthStore } from "../store/useAuthStore";
 import { useKeyStore } from "../store/useKeyStore";
+import { CryptoUtils } from "../utils/crypto";
 import {
   clearMasterKey,
   loadMasterKey,
@@ -14,6 +15,7 @@ import {
 import { useAuth } from "./useAuth";
 
 vi.mock("../utils/keystore");
+vi.mock("../utils/crypto");
 
 const VITE_API_URL = "http://piku-server";
 
@@ -30,6 +32,11 @@ beforeEach(() => {
     isInitializing: true,
   });
   useKeyStore.setState({ masterKey: null });
+
+  vi.mocked(CryptoUtils.deriveKeyBundle).mockResolvedValue({
+    masterKey: mockMasterKey,
+    authHash: "mock-hash",
+  });
 });
 
 describe("isAuthenticated", () => {
@@ -201,3 +208,68 @@ describe("initialize", () => {
     expect(useKeyStore.getState().masterKey).not.toBeNull();
   });
 });
+
+describe("unlock", () => {
+  beforeEach(() => {
+    useAuthStore.setState({
+      accessToken: "valid-token",
+      user: mockUser,
+      isInitializing: false,
+    });
+  });
+
+  it("should derive the master key from the user password, validate it via API, and persist it", async () => {
+    let loginCalled = false;
+    server.use(
+      http.post(`${VITE_API_URL}/api/auth/login/`, async () => {
+        loginCalled = true;
+        return HttpResponse.json({ access: "token", user: mockUser });
+      }),
+    );
+    const { result } = renderHook(() => useAuth());
+
+    await act(async () => {
+      await result.current.unlock("password");
+    });
+
+    expect(CryptoUtils.deriveKeyBundle).toHaveBeenCalledWith(
+      "password",
+      mockUser.email,
+    );
+    expect(loginCalled).toBe(true);
+    expect(saveMasterKey).toHaveBeenCalledWith(mockMasterKey);
+    expect(useKeyStore.getState().masterKey).toEqual(mockMasterKey);
+  });
+
+  it("should logout if user is not present", async () => {
+    useAuthStore.setState({ user: null });
+    const { result } = renderHook(() => useAuth());
+
+    await act(async () => {
+      await result.current.unlock("password");
+    });
+
+    expect(CryptoUtils.deriveKeyBundle).not.toHaveBeenCalled();
+    expect(saveMasterKey).not.toHaveBeenCalled();
+    expect(useAuthStore.getState().accessToken).toBeNull();
+    expect(clearMasterKey).toHaveBeenCalled();
+  });
+
+  it("should throw an error and not persist the key if validation fails", async () => {
+    server.use(
+      http.post(
+        `${VITE_API_URL}/api/auth/login/`,
+        () => new HttpResponse(null, { status: 400 }),
+      ),
+    );
+
+    const { result } = renderHook(() => useAuth());
+
+    await act(async () => {
+      await expect(result.current.unlock("wrong-password")).rejects.toThrow();
+    });
+
+    expect(saveMasterKey).not.toHaveBeenCalled();
+    expect(useKeyStore.getState().masterKey).toBeNull();
+  });
+});
diff --git a/frontend/src/hooks/useAuth.ts b/frontend/src/hooks/useAuth.ts
index 9cd9815..ca2b8ca 100644
--- a/frontend/src/hooks/useAuth.ts
+++ b/frontend/src/hooks/useAuth.ts
@@ -57,7 +57,6 @@ export const useAuth = () => {
     }
 
     try {
-      // try session refresh
       const { data: refreshData } = await publicApi.post(endpoints.REFRESH);
       const { data: userData } = await api.get(endpoints.ME, {
         headers: { Authorization: `Bearer ${refreshData.access}` },
@@ -71,16 +70,24 @@ export const useAuth = () => {
   }, [setMasterKey]);
 
   const unlock = async (password: string) => {
-    if (!user) return;
+    if (!user) {
+      await logout();
+      return;
+    }
 
-    try {
-      const { masterKey } = await CryptoUtils.deriveKeyBundle(
-        password,
-        user.email,
-      );
-      await saveMasterKey(masterKey);
-      setMasterKey(masterKey);
-    } catch {}
+    const { masterKey, authHash } = await CryptoUtils.deriveKeyBundle(
+      password,
+      user.email,
+    );
+
+    // Validate password by calling login endpoint
+    await api.post(endpoints.LOGIN, {
+      email: user.email,
+      password: authHash,
+    });
+
+    await saveMasterKey(masterKey);
+    setMasterKey(masterKey);
   };
 
   return {
diff --git a/frontend/src/pages/Drawer.test.tsx b/frontend/src/pages/Drawer.test.tsx
index e8657c6..05feade 100644
--- a/frontend/src/pages/Drawer.test.tsx
+++ b/frontend/src/pages/Drawer.test.tsx
@@ -9,73 +9,75 @@ import Drawer from "./Drawer";
 vi.mock("../hooks/useLetters");
 
 describe("Drawer Page", () => {
-  beforeEach(() => {
-    // Setup authenticated state for the test
-    useAuthStore.setState({
-      user: mockUser,
-      accessToken: "fake-token",
-      isInitializing: false,
+    beforeEach(() => {
+        // Setup authenticated state for the test
+        useAuthStore.setState({
+            user: mockUser,
+            accessToken: "fake-token",
+            isInitializing: false,
+        });
+
+        vi.mocked(useLetters).mockReturnValue({
+            drafts: [],
+            kept: [],
+            sent: [],
+            vault: [],
+            loading: false,
+            isAuthRequired: false,
+        });
     });
 
-    vi.mocked(useLetters).mockReturnValue({
-      drafts: [],
-      kept: [],
-      sent: [],
-      vault: [],
-      loading: false,
-      isAuthRequired: false,
-    });
-  });
+    it("renders the cabinet sections and empty state message", () => {
+        render(
+            <MemoryRouter>
+                <Drawer />
+            </MemoryRouter>,
+        );
 
-  it("renders the cabinet sections and empty state message", () => {
-    render(
-      <MemoryRouter>
-        <Drawer />
-      </MemoryRouter>,
-    );
-
-    expect(screen.getByText(/Drafts/i)).toBeInTheDocument();
-    expect(screen.getAllByText(/Kept/i).length).toBeGreaterThanOrEqual(1);
-    expect(screen.getByText(/Vault/i)).toBeInTheDocument();
-    expect(screen.getByText(/This drawer remains silent/i)).toBeInTheDocument();
-  });
-
-  it("renders the loading state", () => {
-    vi.mocked(useLetters).mockReturnValue({
-      drafts: [],
-      kept: [],
-      sent: [],
-      vault: [],
-      loading: true,
-      isAuthRequired: false,
+        expect(screen.getByText(/Drafts/i)).toBeInTheDocument();
+        expect(screen.getAllByText(/Kept/i).length).toBeGreaterThanOrEqual(1);
+        expect(screen.getByText(/Vault/i)).toBeInTheDocument();
+        expect(screen.getByText(/This drawer remains silent/i)).toBeInTheDocument();
     });
 
-    render(
-      <MemoryRouter>
-        <Drawer />
-      </MemoryRouter>,
-    );
+    it("renders the loading state", () => {
+        vi.mocked(useLetters).mockReturnValue({
+            drafts: [],
+            kept: [],
+            sent: [],
+            vault: [],
+            loading: true,
+            isAuthRequired: false,
+        });
 
-    expect(screen.getByText(/Opening your cabinet/i)).toBeInTheDocument();
-  });
+        render(
+            <MemoryRouter>
+                <Drawer />
+            </MemoryRouter>,
+        );
 
-  it("renders the authentication required modal when api requires auth", () => {
-    vi.mocked(useLetters).mockReturnValue({
-      drafts: [],
-      kept: [],
-      sent: [],
-      vault: [],
-      loading: false,
-      isAuthRequired: true,
+        expect(screen.getByText(/Opening your cabinet/i)).toBeInTheDocument();
     });
 
-    render(
-      <MemoryRouter>
-        <Drawer />
-      </MemoryRouter>,
-    );
+    it("renders the authentication required modal when api requires auth", () => {
+        vi.mocked(useLetters).mockReturnValue({
+            drafts: [],
+            kept: [],
+            sent: [],
+            vault: [],
+            loading: false,
+            isAuthRequired: true,
+        });
 
-    expect(screen.getByText(/Authentication Required/i)).toBeInTheDocument();
-    expect(screen.getByPlaceholderText(/password/i)).toBeInTheDocument();
-  });
+        render(
+            <MemoryRouter>
+                <Drawer />
+            </MemoryRouter>,
+        );
+
+        expect(
+            screen.getByText(/You've been away a while./i),
+        ).toBeInTheDocument();
+        expect(screen.getByPlaceholderText(/password/i)).toBeInTheDocument();
+    });
 });
diff --git a/frontend/src/pages/Drawer.tsx b/frontend/src/pages/Drawer.tsx
index 19a958b..5fe14f4 100644
--- a/frontend/src/pages/Drawer.tsx
+++ b/frontend/src/pages/Drawer.tsx
@@ -15,7 +15,7 @@ import {
 } from "../utils/dateFormat.ts";
 
 export default function Drawer() {
-  const { user, logout, unlock } = useAuth();
+  const { user, logout } = useAuth();
 
   const [openSection, setOpenSection] = useState<string | null>(null);
   const navigate = useNavigate();
@@ -30,7 +30,7 @@ export default function Drawer() {
     <div className="min-h-screen w-full bg-base-100 text-base-content flex flex-col items-center py-12 px-5 pb-32 font-serif transition-colors">
       <div className="fixed inset-0 bg-vig pointer-events-none z-0" />
 
-      {isAuthRequired && <PasskeyModal onUnlock={unlock} />}
+      {isAuthRequired && <PasskeyModal />}
       <header className="text-center mb-12 z-10 animate-in fade-in slide-in-from-top-4 duration-500">
         <Logo />
         <div className="font-sans text-xs tracking-widester uppercase text-base-content/40 mt-2">