1 files changed, 29 insertions, 62 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/app.js b/packages/meshbay-hub/src/meshbay_hub/static/app.js
index 94bf09e..300059d 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/app.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/app.js
@@ -144,24 +144,24 @@ function passwordBits(pw) {
 const PASSWORD_MIN_BITS = 60;   // refuse below this
 const PASSWORD_MIN_LEN = 12;
 
-// Whether this account backs its encrypted keys up to the nodes it joins.
-//
-// On: any browser recovers the same identity with the password — the ordinary
-// multi-device expectation. Off: the keys exist only where they were generated,
-// nothing is left on anyone's disk, and losing this browser's storage loses the
-// account's content for good. That is a real choice, so it is the user's.
-const KEY_BACKUP_PREFIX = 'mb_key_backup_';
-
-function keyBackupEnabled(username) {
-  try {
-    return localStorage.getItem(KEY_BACKUP_PREFIX + username) !== '0';
-  } catch { return true; }
-}
-
-function setKeyBackupEnabled(username, on) {
+/**
+ * Re-encrypt a bundle written under the old KDF before it is stored again.
+ *
+ * PBKDF2 bundles are still readable, but leaving one on a node keeps the weak
+ * protection alive for as long as it sits there. Any backup is an opportunity to
+ * replace it with the Argon2id form, and it costs nothing the user notices.
+ */
+async function _upgradedBundle(bundleEnc) {
   try {
-    localStorage.setItem(KEY_BACKUP_PREFIX + username, on ? '1' : '0');
-  } catch {}
+    if (!window.MeshBayKeys || !_sessionKeys || !_bundleKey) return bundleEnc;
+    if (window.MeshBayKeys.bundleVersion(bundleEnc) === 2) return bundleEnc;
+    const b64 = (s) => Uint8Array.from(atob(s), c => c.charCodeAt(0));
+    return await window.MeshBayKeys.encryptBundleWithKey(
+      b64(_sessionKeys.skEdB64), b64(_sessionKeys.skXB64), _bundleKey.v2);
+  } catch (e) {
+    console.warn('[MeshBay] bundle upgrade skipped:', e.message);
+    return bundleEnc;
+  }
 }
 
 function _restoreSessionKeys() {
@@ -979,26 +979,18 @@ function GroupPage({ groupId, group, token, username, userId, onRefreshAuth }) {
           }
         }
 
-        // Back the encrypted keys up to the node, or withdraw them — whichever
-        // this account asked for. The local copy is only dropped once the node
-        // holds one, so turning backup off never strands anybody.
-        if (transport.connected) {
-          if (keyBackupEnabled(username)) {
-            if (_pendingBundlePush) {
-              try {
-                await transport.storeKeypairBundle(_pendingBundlePush);
-                try { localStorage.removeItem(`meshbay_kp_${username}`); } catch {}
-                _pendingBundlePush = null;
-              } catch (e) {
-                console.warn('[MeshBay] Bundle push to node deferred:', e.message);
-              }
-            }
-          } else {
-            try {
-              await transport.deleteKeypairBundle();
-            } catch (e) {
-              console.warn('[MeshBay] Could not withdraw key backup:', e.message);
-            }
+        // Back the encrypted keys up to the node. This is what lets any other
+        // browser recover them with the passphrase, which is the ordinary
+        // expectation; the protection that matters is the KDF guarding the
+        // bundle, not withholding the bundle.
+        if (transport.connected && _pendingBundlePush) {
+          try {
+            await transport.storeKeypairBundle(
+              await _upgradedBundle(_pendingBundlePush));
+            try { localStorage.removeItem(`meshbay_kp_${username}`); } catch {}
+            _pendingBundlePush = null;
+          } catch (e) {
+            console.warn('[MeshBay] Bundle push to node deferred:', e.message);
           }
         }
 
@@ -2206,15 +2198,6 @@ function SettingsPage({ user, theme, onThemeChange, groups }) {
   const [nodeKeyLoading, setNodeKeyLoading] = useState(false);
   const [pinCount, setPinCount] = useState(
     () => (window.MeshBayTransport?.pinnedNodeCount?.() ?? 0));
-  const [backup, setBackup] = useState(() => keyBackupEnabled(user.username));
-
-  // Takes effect on the next connection to each node: enabling uploads the
-  // encrypted bundle, disabling withdraws whatever that node already holds.
-  const toggleBackup = useCallback(() => {
-    const next = !backup;
-    setKeyBackupEnabled(user.username, next);
-    setBackup(next);
-  }, [backup, user.username]);
 
   // 11.5.8: node identity pins are refused strictly on change, so users need a
   // deliberate way to accept a legitimate rotation (operator reinstalled a node).
@@ -2313,22 +2296,6 @@ function SettingsPage({ user, theme, onThemeChange, groups }) {
       </div>
 
       <div class="settings-section">
-        <h3 class="settings-heading">${t('settings.key_backup')}</h3>
-        <p class="settings-hint">${t('settings.key_backup_hint')}</p>
-        <div class="settings-row">
-          <span class="settings-label">
-            ${backup ? t('settings.key_backup_on') : t('settings.key_backup_off')}
-          </span>
-          <button class="btn-secondary" onClick=${toggleBackup}>
-            ${backup ? t('settings.key_backup_disable') : t('settings.key_backup_enable')}
-          </button>
-        </div>
-        ${!backup && html`
-          <p class="error-msg" style="margin-top:8px">${t('settings.key_backup_warning')}</p>
-        `}
-      </div>
-
-      <div class="settings-section">
         <h3 class="settings-heading">${t('settings.node_pins')}</h3>
         <p class="settings-hint">${t('settings.node_pins_hint')}</p>
         <div class="settings-row">