feat: Phase 12 — P2P crypto material, password split, node Ed25519 auth

Baseline commit capturing in-progress Phase 12 work that was already present
in the working tree (uncommitted) before the Phase 11.5 security remediation
begins. Committed as-is, without review or modification, so that remediation
changes arrive as a separable diff.

Contents: BundleStore (P2P GEK + keypair bundles), password split
(auth_key / bundle_key), node Ed25519 auth (POST /v1/nodes/auth, node-scoped
JWT), GEK-HMAC handshake proof with DTLS channel binding, Ed25519 admin
challenge-response, node local admin UI rewrite, browser key persistence.

Not authored in this session — captured to establish a baseline.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

1 files changed, 160 insertions, 3 deletions

diff --git a/packages/meshbay-node/src/meshbay_node/ui/app.py b/packages/meshbay-node/src/meshbay_node/ui/app.py
index 5e77ed8..b4885af 100644
--- a/packages/meshbay-node/src/meshbay_node/ui/app.py
+++ b/packages/meshbay-node/src/meshbay_node/ui/app.py
@@ -12,15 +12,17 @@ Served only on 127.0.0.1 — not exposed to the network.
 No authentication required (localhost only).
 """
 
+import base64
 import json
 import logging
 import time
 from pathlib import Path
 
 from fastapi import FastAPI, WebSocket, WebSocketDisconnect, Query
-from fastapi.responses import HTMLResponse
+from fastapi.responses import HTMLResponse, JSONResponse
 
 from meshbay_node import __version__
+from meshbay_common.crypto import generate_gek, wrap_gek_aes
 
 log = logging.getLogger(__name__)
 
@@ -52,6 +54,7 @@ def create_ui_app(state: dict) -> FastAPI:
             "group_count": len(groups_ctx),
             "total_files": total_files,
             "webrtc_peers": webrtc.active_peers if webrtc else 0,
+            "pk_node_ed25519": state.get("pk_node_ed25519", ""),
         }
 
     @app.get("/api/groups")
@@ -167,6 +170,95 @@ def create_ui_app(state: dict) -> FastAPI:
             ],
         }
 
+    # ── GEK initialization (operator only, localhost) ──────────────────────
+
+    @app.post("/api/groups/{group_id}/gek")
+    async def init_gek(group_id: str):
+        """Generate GEK, wrap for all group members, store, and activate."""
+        groups_ctx = state.get("groups_ctx", {})
+        if group_id not in groups_ctx:
+            return JSONResponse({"error": "Group not hosted on this node"}, 404)
+
+        hub = state.get("hub")
+        if not hub or not hub._session:
+            return JSONResponse({"error": "Hub not connected"}, 503)
+
+        bundle_store = state.get("bundle_store")
+        if not bundle_store:
+            return JSONResponse({"error": "Bundle store not available"}, 503)
+
+        await hub.ensure_fresh_token()
+        session = hub._session
+        members_resp = await hub._http.get(
+            f"/v1/groups/{group_id}/members",
+            headers=session.auth_headers,
+        )
+        if not members_resp.is_success:
+            return JSONResponse(
+                {"error": f"Failed to fetch members: {members_resp.status_code}"}, 502)
+        members = members_resp.json().get("members", [])
+        if not members:
+            return JSONResponse({"error": "No members in group"}, 400)
+
+        existing_gek = groups_ctx[group_id].get("gek")
+        gek = existing_gek or generate_gek()
+
+        wrapped_count = 0
+        errors = []
+        for member in members:
+            username = member["username"]
+            user_id = member["user_id"]
+            try:
+                pk_data = await hub.get_user_pubkeys(username)
+                pk_x_raw = base64.b64decode(pk_data["pk_x25519"])
+                bundle = wrap_gek_aes(gek, pk_x_raw)
+                await bundle_store.store(
+                    group_id, user_id,
+                    bundle["pk_eph_b64"], bundle["nonce_b64"], bundle["wrapped_b64"],
+                )
+                wrapped_count += 1
+                log.info("GEK wrapped for %s (%s)", username, user_id[:8])
+            except Exception as e:
+                errors.append(f"{username}: {e}")
+                log.warning("Failed to wrap GEK for %s: %s", username, e)
+
+        if wrapped_count == 0:
+            return JSONResponse(
+                {"error": "Failed to wrap GEK for any member", "details": errors}, 500)
+
+        # Also store a copy wrapped for the node keystore X25519 key
+        # so the daemon can reload GEK on restart without the operator's browser keys
+        config = state.get("config")
+        node_user_id = hub._session.user_id if hub._session else None
+        pk_x_node_raw = state.get("pk_x25519_raw")
+        if pk_x_node_raw and node_user_id:
+            try:
+                node_bundle = wrap_gek_aes(gek, pk_x_node_raw)
+                await bundle_store.store(
+                    group_id, f"_node_{node_user_id}",
+                    node_bundle["pk_eph_b64"], node_bundle["nonce_b64"],
+                    node_bundle["wrapped_b64"],
+                )
+                log.info("GEK also wrapped for node keystore (daemon reload)")
+            except Exception as e:
+                log.warning("Failed to wrap GEK for node keystore: %s", e)
+
+        groups_ctx[group_id]["gek"] = gek
+        log.info("GEK initialized for group %s — wrapped for %d/%d members",
+                 group_id[:8], wrapped_count, len(members))
+
+        webrtc = state.get("webrtc")
+        if webrtc and "groups" in webrtc._ctx and group_id in webrtc._ctx["groups"]:
+            webrtc._ctx["groups"][group_id]["gek"] = gek
+
+        return {
+            "status": "ok",
+            "group_id": group_id,
+            "wrapped_count": wrapped_count,
+            "total_members": len(members),
+            "errors": errors,
+        }
+
     # ── Chat endpoints ───────────────────────────────────────────────────────
 
     _chat_subscribers: list[WebSocket] = []
@@ -246,7 +338,10 @@ def _render_page(state: dict) -> str:
     webrtc = state.get("webrtc")
     total_files = sum(idx.count for idx in indexes.values())
     peer_count = webrtc.active_peers if webrtc else 0
-    status_color = {"running": "#22c55e", "error": "#ef4444"}.get(status, "#f59e0b")
+    status_color = {
+        "running": "#22c55e", "error": "#ef4444",
+        "waiting_for_node_key": "#f97316",
+    }.get(status, "#f59e0b")
 
     # Groups section
     groups_html = ""
@@ -269,13 +364,34 @@ def _render_page(state: dict) -> str:
                     f"<td>{_fmt_size(e.size)}</td><td>{e.path or '/'}</td></tr>"
                 )
 
+        has_gek = bool(ctx.get("gek"))
+        gek_badge = (
+            '<span class="badge" style="background:#22c55e">GEK active</span>'
+            if has_gek
+            else '<span class="badge" style="background:#ef4444">No GEK</span>'
+        )
+        gek_label = "Re-wrap GEK for all members" if has_gek else "Initialize GEK"
+        gek_color = "#3b82f6" if has_gek else "#22c55e"
+        gek_action = f"""
+            <div style="margin:10px 0">
+              <button onclick="initGEK('{gid}')"
+                id="gek-btn-{gid[:8]}"
+                style="padding:8px 16px;background:{gek_color};color:#fff;border:none;
+                border-radius:6px;cursor:pointer;font-size:0.85em">
+                {gek_label}
+              </button>
+              <span id="gek-status-{gid[:8]}" class="muted" style="margin-left:8px"></span>
+            </div>"""
+
         groups_html += f"""
         <div class="card">
           <h3>{name}
             <span class="badge" style="background:#6366f1">{vis}</span>
+            {gek_badge}
           </h3>
           <p><b>Directory:</b> <code>{shared}</code></p>
           <p><b>Files:</b> {fcount} &mdash; <b>Total:</b> {_fmt_size(total_size)}</p>
+          {gek_action}
           <p class="muted">ID: {gid}</p>
           <details><summary>File list</summary>
           <table>
@@ -382,6 +498,21 @@ def _render_page(state: dict) -> str:
     <p><b>Node ID:</b> <code>{state.get("endpoint_hint") or "—"}</code></p>
   </div>
 
+  <h2>Link Node to Hub Account</h2>
+  <div class="card">
+    <p>To connect to your group from a browser, link this node to your hub account.
+       Copy the key below and paste it in <b>Settings &gt; Link Node</b> on the hub.</p>
+    <div style="margin:12px 0;display:flex;align-items:center;gap:8px">
+      <code id="nodeKey" style="flex:1;padding:8px;word-break:break-all;background:var(--border);
+        border-radius:4px;font-size:0.9em;user-select:all">{state.get("pk_node_ed25519", "—")}</code>
+      <button onclick="navigator.clipboard.writeText(document.getElementById('nodeKey').textContent).then(()=>{{this.textContent='Copied!';setTimeout(()=>this.textContent='Copy',2000)}})"
+        style="padding:8px 16px;background:var(--accent);color:#fff;border:none;border-radius:6px;
+        cursor:pointer;font-size:0.85em;white-space:nowrap">Copy</button>
+    </div>
+    <p class="muted">This is the node's Ed25519 public key. It's safe to share — it identifies
+       this node but cannot be used to impersonate it.</p>
+  </div>
+
   <div class="footer">
     MeshBay Node v{__version__} &mdash; localhost only &mdash;
     <a href="/api/status">status</a> &middot;
@@ -392,7 +523,33 @@ def _render_page(state: dict) -> str:
     &mdash; auto-refresh 10s
   </div>
 </div>
-<script>setTimeout(()=>location.reload(), 10000);</script>
+<script>
+async function initGEK(groupId) {{
+  const btn = document.getElementById('gek-btn-' + groupId.slice(0,8));
+  const status = document.getElementById('gek-status-' + groupId.slice(0,8));
+  if (btn) btn.disabled = true;
+  if (status) status.textContent = 'Initializing...';
+  try {{
+    const resp = await fetch('/api/groups/' + groupId + '/gek', {{ method: 'POST' }});
+    const data = await resp.json();
+    if (resp.ok) {{
+      if (status) status.textContent = 'GEK initialized — wrapped for '
+        + data.wrapped_count + '/' + data.total_members + ' members';
+      if (status) status.style.color = '#22c55e';
+      setTimeout(() => location.reload(), 2000);
+    }} else {{
+      if (status) status.textContent = data.error || 'Failed';
+      if (status) status.style.color = '#ef4444';
+      if (btn) btn.disabled = false;
+    }}
+  }} catch (e) {{
+    if (status) status.textContent = 'Error: ' + e.message;
+    if (status) status.style.color = '#ef4444';
+    if (btn) btn.disabled = false;
+  }}
+}}
+setTimeout(()=>location.reload(), 10000);
+</script>
 </body>
 </html>"""