1 files changed, 37 insertions, 1 deletions
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/crypto.js b/packages/meshbay-hub/src/meshbay_hub/static/crypto.js
index 5ebf624..2346fa2 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/crypto.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/crypto.js
@@ -230,6 +230,42 @@ function b64encode(bytes) {
   return btoa(String.fromCharCode(...bytes));
 }
 
+// ── Admin operation transcript ───────────────────────────────────────────────
+// Mirrors meshbay_common/adminop.py::admin_transcript(). Both sides build these
+// bytes independently; they are never taken off the wire.
+//
+// Finding H5: the client used to sign 32 raw random bytes chosen by the node — a
+// blind signing oracle. It now reconstructs a domain-separated, length-prefixed
+// transcript naming the operation, subject, node and group, so the UI can show the
+// user what they are authorizing and a signature cannot be reused elsewhere.
+
+const ADMIN_TRANSCRIPT_PREFIX = new TextEncoder().encode('meshbay:admin:v1');
+
+function adminTranscript(op, nodePkB64, groupId, subject, nonceB64, ts) {
+  const enc = new TextEncoder();
+  const fields = [
+    enc.encode(op),
+    enc.encode(nodePkB64),
+    enc.encode(groupId),
+    enc.encode(subject),
+    b64decode(nonceB64),
+    enc.encode(String(ts)),
+  ];
+  let total = ADMIN_TRANSCRIPT_PREFIX.length;
+  for (const f of fields) total += 4 + f.length;
+
+  const out = new Uint8Array(total);
+  out.set(ADMIN_TRANSCRIPT_PREFIX, 0);
+  let off = ADMIN_TRANSCRIPT_PREFIX.length;
+  for (const f of fields) {
+    new DataView(out.buffer).setUint32(off, f.length, false);
+    off += 4;
+    out.set(f, off);
+    off += f.length;
+  }
+  return out;
+}
+
 // ── GEK proof (HMAC-SHA256 for handshake challenge) ─────────────────────────
 
 async function hmacGEK(gekRaw, nonceB64, offerFp, answerFp) {
@@ -249,5 +285,5 @@ async function hmacGEK(gekRaw, nonceB64, offerFp, answerFp) {
 window.MeshBayCrypto = {
   importGEK, deriveChunkKey, decryptChunk, decryptChunkBin, decryptFile,
   generateGEK, wrapGEK, unwrapGEK, encryptChunk, b64encode, b64decode,
-  hmacGEK,
+  hmacGEK, adminTranscript,
 };