feat: Phase 10b — Self-service UI (group create/join, upload, IndexedDB, search)

Six self-service features for the web SPA:
- Group creation UI with GEK auto-generation (AES-256-GCM ECIES)
- Member management + invite by username (GEK wrapping for invitee)
- Open group self-join flow (POST /v1/groups/{id}/join)
- File upload client→node (FILE_UPLOAD MNP type, .uploads/ staging)
- IndexedDB caching of group file indexes (instant display on revisit)
- Cross-group file search (SearchPage, pure client-side on cached indexes)

11 new tests (166 total): 8 group self-service + 3 AES GEK wrap/unwrap.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 77 insertions, 2 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/crypto.js b/packages/meshbay-hub/src/meshbay_hub/static/crypto.js
index ee442fb..eb96eef 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/crypto.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/crypto.js
@@ -56,7 +56,7 @@ async function deriveChunkKey(gek, fileHashHex, chunkIndex) {
     gek,
     { name: 'AES-GCM', length: 256 },
     false,
-    ['decrypt'],
+    ['encrypt', 'decrypt'],
   );
 }
 
@@ -158,5 +158,80 @@ async function decryptChunkBin(gek, fileHashHex, chunkIndex, nonce, ct) {
   return new Uint8Array(plaintext);
 }
 
+// ── GEK generation + ECIES wrapping ──────────────────────────────────────────
+
+function generateGEK() {
+  return crypto.getRandomValues(new Uint8Array(32));
+}
+
+async function wrapGEK(gek, pkXRaw) {
+  const skEph = await crypto.subtle.generateKey({ name: 'X25519' }, true, ['deriveBits']);
+  const pkEphRaw = new Uint8Array(await crypto.subtle.exportKey('raw', skEph.publicKey));
+
+  const pkRecip = await crypto.subtle.importKey('raw', pkXRaw, { name: 'X25519' }, false, []);
+  const sharedBits = await crypto.subtle.deriveBits(
+    { name: 'X25519', public: pkRecip }, skEph.privateKey, 256);
+
+  const sharedKey = await crypto.subtle.importKey(
+    'raw', sharedBits, 'HKDF', false, ['deriveKey']);
+  const wrapKey = await crypto.subtle.deriveKey(
+    { name: 'HKDF', hash: 'SHA-256', salt: pkEphRaw,
+      info: new TextEncoder().encode('meshbay:gek_wrap:v1:aes') },
+    sharedKey,
+    { name: 'AES-GCM', length: 256 }, false, ['encrypt']);
+
+  const nonce = crypto.getRandomValues(new Uint8Array(12));
+  const ct = await crypto.subtle.encrypt(
+    { name: 'AES-GCM', iv: nonce, additionalData: pkXRaw }, wrapKey, gek);
+
+  return {
+    pk_eph_b64: btoa(String.fromCharCode(...pkEphRaw)),
+    nonce_b64: btoa(String.fromCharCode(...nonce)),
+    wrapped_b64: btoa(String.fromCharCode(...new Uint8Array(ct))),
+  };
+}
+
+async function unwrapGEK(bundle, skXPkcs8, pkXRaw) {
+  const pkEphRaw = b64decode(bundle.pk_eph_b64);
+  const nonce = b64decode(bundle.nonce_b64);
+  const wrapped = b64decode(bundle.wrapped_b64);
+
+  const skX = await crypto.subtle.importKey(
+    'pkcs8', skXPkcs8, { name: 'X25519' }, false, ['deriveBits']);
+  const pkEph = await crypto.subtle.importKey(
+    'raw', pkEphRaw, { name: 'X25519' }, false, []);
+  const sharedBits = await crypto.subtle.deriveBits(
+    { name: 'X25519', public: pkEph }, skX, 256);
+
+  const sharedKey = await crypto.subtle.importKey(
+    'raw', sharedBits, 'HKDF', false, ['deriveKey']);
+  const wrapKey = await crypto.subtle.deriveKey(
+    { name: 'HKDF', hash: 'SHA-256', salt: pkEphRaw,
+      info: new TextEncoder().encode('meshbay:gek_wrap:v1:aes') },
+    sharedKey,
+    { name: 'AES-GCM', length: 256 }, false, ['decrypt']);
+
+  const plain = await crypto.subtle.decrypt(
+    { name: 'AES-GCM', iv: nonce, additionalData: pkXRaw }, wrapKey, wrapped);
+  return new Uint8Array(plain);
+}
+
+// ── Chunk encryption (for upload) ────────────────────────────────────────────
+
+async function encryptChunk(gek, fileHashHex, chunkIndex, plaintext) {
+  const chunkKey = await deriveChunkKey(gek, fileHashHex, chunkIndex);
+  const nonce = crypto.getRandomValues(new Uint8Array(12));
+  const ct = await crypto.subtle.encrypt(
+    { name: 'AES-GCM', iv: nonce }, chunkKey, plaintext);
+  return { nonce, ct: new Uint8Array(ct) };
+}
+
+function b64encode(bytes) {
+  return btoa(String.fromCharCode(...bytes));
+}
+
 // Export for use in app.js
-window.MeshBayCrypto = { importGEK, deriveChunkKey, decryptChunk, decryptChunkBin, decryptFile };
+window.MeshBayCrypto = {
+  importGEK, deriveChunkKey, decryptChunk, decryptChunkBin, decryptFile,
+  generateGEK, wrapGEK, unwrapGEK, encryptChunk, b64encode, b64decode,
+};