diff --git a/index.html b/index.html
index 38264f0..6a32f11 100644
--- a/index.html
+++ b/index.html
@@ -523,6 +523,7 @@
     <!-- Hero -->
     <section class="hero">
         <div class="badge">Part of the rSpace Ecosystem</div>
+        <div id="encryptid-auth" style="margin-bottom:16px;min-height:32px;"></div>
         <h1><span>Democratic Wallet Management</span><br>for Communities</h1>
         <p class="hero-sub">
             Interactive visualizations for <strong>group treasury management</strong>.
@@ -750,7 +751,11 @@
         <p>No backend. No tracking. All data fetched client-side from public APIs.</p>
     </footer>
 
+    <script src="js/encryptid.js"></script>
     <script>
+        // ─── EncryptID Auth ────────────────────────────────────────
+        EncryptID.renderAuthButton('encryptid-auth');
+
         // ─── Wallet Input Logic ────────────────────────────────────
         const DEMO_ADDRESS = '0x29567BdBcC92aCF37AC6B56B69180857bB69f7D1';
 
diff --git a/js/encryptid.js b/js/encryptid.js
new file mode 100644
index 0000000..2c5e0e5
--- /dev/null
+++ b/js/encryptid.js
@@ -0,0 +1,245 @@
+/**
+ * EncryptID Authentication for rWallet.online
+ *
+ * Adds optional passkey-based identity to the static wallet explorer.
+ * When authenticated, the user gets a persistent identity and can
+ * associate wallet addresses with their account.
+ */
+
+const EncryptID = (() => {
+    const SERVER = 'https://encryptid.jeffemmett.com';
+    const STORAGE_KEY = 'rwallet_encryptid';
+
+    // ─── Helpers ─────────────────────────────────────────────────
+    function toBase64url(buffer) {
+        return btoa(String.fromCharCode(...new Uint8Array(buffer)))
+            .replace(/\+/g, '-')
+            .replace(/\//g, '_')
+            .replace(/=+$/g, '');
+    }
+
+    function fromBase64url(str) {
+        return Uint8Array.from(
+            atob(str.replace(/-/g, '+').replace(/_/g, '/')),
+            c => c.charCodeAt(0)
+        );
+    }
+
+    function getStoredAuth() {
+        try {
+            const raw = localStorage.getItem(STORAGE_KEY);
+            return raw ? JSON.parse(raw) : null;
+        } catch { return null; }
+    }
+
+    function setStoredAuth(auth) {
+        localStorage.setItem(STORAGE_KEY, JSON.stringify(auth));
+    }
+
+    function clearStoredAuth() {
+        localStorage.removeItem(STORAGE_KEY);
+    }
+
+    // ─── Authentication ──────────────────────────────────────────
+
+    async function authenticate() {
+        // Step 1: Get challenge
+        const startRes = await fetch(`${SERVER}/api/auth/start`, {
+            method: 'POST',
+            headers: { 'Content-Type': 'application/json' },
+            body: JSON.stringify({}),
+        });
+        const { options } = await startRes.json();
+
+        // Step 2: WebAuthn ceremony
+        const assertion = await navigator.credentials.get({
+            publicKey: {
+                challenge: fromBase64url(options.challenge),
+                rpId: options.rpId,
+                userVerification: options.userVerification,
+                timeout: options.timeout,
+                allowCredentials: options.allowCredentials?.map(c => ({
+                    type: c.type,
+                    id: fromBase64url(c.id),
+                    transports: c.transports,
+                })),
+            },
+        });
+
+        const response = assertion.response;
+
+        // Step 3: Complete
+        const completeRes = await fetch(`${SERVER}/api/auth/complete`, {
+            method: 'POST',
+            headers: { 'Content-Type': 'application/json' },
+            body: JSON.stringify({
+                challenge: options.challenge,
+                credential: {
+                    credentialId: assertion.id,
+                    authenticatorData: toBase64url(response.authenticatorData),
+                    clientDataJSON: toBase64url(response.clientDataJSON),
+                    signature: toBase64url(response.signature),
+                    userHandle: response.userHandle ? toBase64url(response.userHandle) : null,
+                },
+            }),
+        });
+
+        const result = await completeRes.json();
+        if (!result.success) throw new Error(result.error || 'Authentication failed');
+
+        const auth = { token: result.token, did: result.did, username: result.username };
+        setStoredAuth(auth);
+        return auth;
+    }
+
+    async function register(username) {
+        // Step 1: Get registration options
+        const startRes = await fetch(`${SERVER}/api/register/start`, {
+            method: 'POST',
+            headers: { 'Content-Type': 'application/json' },
+            body: JSON.stringify({ username, displayName: username }),
+        });
+        const { options, userId } = await startRes.json();
+
+        // Step 2: WebAuthn ceremony
+        const credential = await navigator.credentials.create({
+            publicKey: {
+                challenge: fromBase64url(options.challenge),
+                rp: options.rp,
+                user: {
+                    id: fromBase64url(options.user.id),
+                    name: options.user.name,
+                    displayName: options.user.displayName,
+                },
+                pubKeyCredParams: options.pubKeyCredParams,
+                authenticatorSelection: options.authenticatorSelection,
+                timeout: options.timeout,
+                attestation: options.attestation,
+            },
+        });
+
+        const response = credential.response;
+
+        // Step 3: Complete
+        const completeRes = await fetch(`${SERVER}/api/register/complete`, {
+            method: 'POST',
+            headers: { 'Content-Type': 'application/json' },
+            body: JSON.stringify({
+                challenge: options.challenge,
+                userId,
+                username,
+                credential: {
+                    credentialId: credential.id,
+                    publicKey: toBase64url(response.getPublicKey?.() || response.attestationObject),
+                    attestationObject: toBase64url(response.attestationObject),
+                    clientDataJSON: toBase64url(response.clientDataJSON),
+                    transports: response.getTransports?.() || [],
+                },
+            }),
+        });
+
+        const result = await completeRes.json();
+        if (!result.success) throw new Error(result.error || 'Registration failed');
+
+        const auth = { token: result.token, did: result.did, username };
+        setStoredAuth(auth);
+        return auth;
+    }
+
+    function logout() {
+        clearStoredAuth();
+    }
+
+    function isAuthenticated() {
+        return !!getStoredAuth();
+    }
+
+    function getUser() {
+        return getStoredAuth();
+    }
+
+    // ─── UI Component ────────────────────────────────────────────
+
+    /**
+     * Render a passkey auth button into the specified container.
+     * Shows sign-in when anonymous, username + sign-out when authenticated.
+     */
+    function renderAuthButton(containerId) {
+        const container = document.getElementById(containerId);
+        if (!container) return;
+
+        function render() {
+            const auth = getStoredAuth();
+
+            if (auth) {
+                container.innerHTML = `
+                    <div style="display:flex;align-items:center;gap:10px;justify-content:center;">
+                        <span style="color:var(--text-dim);font-size:0.85rem;">
+                            Signed in as <strong style="color:var(--primary);">${auth.username || auth.did?.slice(0, 16) + '...'}</strong>
+                        </span>
+                        <button id="eid-signout" style="background:none;border:1px solid var(--border);color:var(--text-dim);padding:4px 12px;border-radius:6px;cursor:pointer;font-size:0.8rem;">
+                            Sign out
+                        </button>
+                    </div>
+                `;
+                document.getElementById('eid-signout').addEventListener('click', () => {
+                    logout();
+                    render();
+                });
+            } else {
+                container.innerHTML = `
+                    <div style="display:flex;align-items:center;gap:8px;justify-content:center;">
+                        <button id="eid-signin" style="background:none;border:1px solid var(--border);color:var(--text-dim);padding:6px 16px;border-radius:8px;cursor:pointer;font-size:0.85rem;display:flex;align-items:center;gap:6px;transition:all 0.2s;">
+                            <svg width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                                <circle cx="12" cy="10" r="3"/><path d="M12 13v8"/><path d="M9 18h6"/><circle cx="12" cy="10" r="7"/>
+                            </svg>
+                            Sign in with Passkey
+                        </button>
+                    </div>
+                `;
+                const btn = document.getElementById('eid-signin');
+                btn.addEventListener('mouseenter', () => { btn.style.borderColor = 'var(--primary)'; btn.style.color = 'var(--primary)'; });
+                btn.addEventListener('mouseleave', () => { btn.style.borderColor = 'var(--border)'; btn.style.color = 'var(--text-dim)'; });
+                btn.addEventListener('click', async () => {
+                    btn.textContent = 'Authenticating...';
+                    btn.disabled = true;
+                    try {
+                        await authenticate();
+                        render();
+                    } catch (e) {
+                        if (e.name === 'NotAllowedError') {
+                            // No passkey found — prompt to register
+                            const name = prompt('No passkey found. Create one?\nEnter a username:');
+                            if (name) {
+                                try {
+                                    await register(name.trim());
+                                    render();
+                                } catch (re) {
+                                    alert('Registration failed: ' + re.message);
+                                    render();
+                                }
+                            } else {
+                                render();
+                            }
+                        } else {
+                            alert('Sign in failed: ' + e.message);
+                            render();
+                        }
+                    }
+                });
+            }
+        }
+
+        render();
+    }
+
+    // ─── Public API ──────────────────────────────────────────────
+    return {
+        authenticate,
+        register,
+        logout,
+        isAuthenticated,
+        getUser,
+        renderAuthButton,
+    };
+})();