1 files changed, 26 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 d18eeae..21bf05d 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/crypto.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/crypto.js
@@ -314,6 +314,31 @@ async function handshakeProof(gekRaw, role, groupId, nonceClient, nonceNode, bin
   return new Uint8Array(sig);
 }
 
+// ── Join / pairing transcript ───────────────────────────────────────────────
+
+// Mirrors meshbay_common/join.py. Signing both of our public keys together binds
+// the X25519 key to the Ed25519 identity the node pins, so the node can safely
+// wrap the group key for a key that came over the wire instead of one fetched
+// from the hub's directory (H3). nonce_node ties it to this connection.
+const JOIN_PREFIX = new TextEncoder().encode('meshbay:join:v1');
+
+function joinTranscript(nodePkB64, groupId, userId, pkEdB64, pkXB64, nonceNode, ts) {
+  const enc = new TextEncoder();
+  const body = _lenPrefixed([
+    enc.encode(nodePkB64),
+    enc.encode(groupId),
+    enc.encode(userId),
+    enc.encode(pkEdB64),
+    enc.encode(pkXB64),
+    nonceNode,
+    enc.encode(String(ts)),
+  ]);
+  const out = new Uint8Array(JOIN_PREFIX.length + body.length);
+  out.set(JOIN_PREFIX, 0);
+  out.set(body, JOIN_PREFIX.length);
+  return out;
+}
+
 function constantTimeEqual(a, b) {
   if (a.length !== b.length) return false;
   let diff = 0;
@@ -333,5 +358,5 @@ window.MeshBayCrypto = {
   importGEK, deriveChunkKey, decryptChunk, decryptChunkBin, decryptFile,
   generateGEK, wrapGEK, unwrapGEK, encryptChunk, b64encode, b64decode,
   adminTranscript, handshakeTranscript, handshakeProof, webrtcBinding,
-  verifyNodeSignature, constantTimeEqual,
+  joinTranscript, verifyNodeSignature, constantTimeEqual,
 };