fix: use peerId in handoff-receive, not publicKey

Author: kumavis

packages/ocapn/src/client/ocapn.js

@@ -704,7 +704,7 @@ const makeBootstrapObject = (
       const {
         signedGive,
         receivingSession,
-        receivingSide: receiverKeyForExporter,
+        receivingSide: peerIdFromHandoffReceive,
         handoffCount,
       } = handoffReceive;
       const { object: handoffGive, signature: handoffGiveSig } = signedGive;
@@ -721,11 +721,12 @@ const makeBootstrapObject = (
           `${label}: Bootstrap withdraw-gift: No peer public key for session id: ${toHex(sessionId)}. This should never happen.`,
         );
       }
+      const peerIdFromSession = makePublicKeyId(peerPublicKey);
       if (
-        compareByteArrays(peerPublicKey.bytes, receiverKeyForExporter) !== 0
+        compareByteArrays(peerIdFromSession, peerIdFromHandoffReceive) !== 0
       ) {
         throw Error(
-          `${label}: Bootstrap withdraw-gift: Receiver key mismatch.`,
+          `${label}: Bootstrap withdraw-gift: Receiver key mismatch for session ${toHex(sessionId)}.\n  peerIdFromSession: ${toHex(peerIdFromSession)}\n  peerIdFromHandoffReceive: ${toHex(peerIdFromHandoffReceive)}`,
         );
       }
       if (compareByteArrays(sessionId, receivingSession) !== 0) {
@@ -1078,21 +1079,28 @@ export const makeOcapn = (
 
   /** @type {MakeHandoff} */
   const makeHandoff = signedGive => {
+    // We are the Receiver.
+    // This peer is the Gifter.
+    // The Exporter is specified by location in the HandoffGive.
+    const gifterLocation = peerLocation;
     const {
       object: { exporterLocation },
     } = signedGive;
     return HandledPromise.resolve(
       (async () => {
         const [receiverGifterSession, receiverExporterSession] =
           await Promise.all([
-            provideSession(peerLocation),
+            provideSession(gifterLocation),
             provideSession(exporterLocation),
           ]);
         const {
           ocapn,
           id: receiverExporterSessionId,
-          self: { keyPair: receiverExporterKey },
+          self: { keyPair: receiverKeyForExporter },
         } = receiverExporterSession;
+        const receiverPeerIdForExporter = makePublicKeyId(
+          receiverKeyForExporter.publicKey,
+        );
         const {
           self: { keyPair: receiverGifterKey },
         } = receiverGifterSession;
@@ -1102,7 +1110,7 @@ export const makeOcapn = (
           signedGive,
           handoffCount,
           receiverExporterSessionId,
-          receiverExporterKey.publicKey,
+          receiverPeerIdForExporter,
           receiverGifterKey,
         );
         return E(bootstrap)['withdraw-gift'](signedHandoffReceive);

packages/ocapn/src/codecs/descriptors.js

@@ -153,23 +153,22 @@ export const serializeHandoffReceive = handoffReceive => {
  * @param {HandoffGiveSigEnvelope} signedGive
  * @param {bigint} handoffCount
  * @param {Uint8Array} sessionId
- * @param {OcapnPublicKey} pubKeyForExporter
+ * @param {Uint8Array} receiverPeerId
  * @param {OcapnKeyPair} privKeyForGifter
  * @returns {HandoffReceiveSigEnvelope}
  */
 export const makeWithdrawGiftDescriptor = (
   signedGive,
   handoffCount,
   sessionId,
-  pubKeyForExporter,
+  receiverPeerId,
   privKeyForGifter,
 ) => {
   /** @type {HandoffReceive} */
   const handoffReceive = {
     type: 'desc:handoff-receive',
     receivingSession: sessionId,
-    // This should be removed from the spec
-    receivingSide: pubKeyForExporter.bytes,
+    receivingSide: receiverPeerId,
     handoffCount,
     signedGive,
   };

packages/ocapn/test/cryptography.test.js

@@ -91,13 +91,16 @@ test('makeWithdrawGiftDescriptor', t => {
       key2: receiverKeyForExporter,
       sessionId: exporterReceiverSessionId,
     } = exporterReceiverSession;
+    const receiverPeerIdForExporter = makePublicKeyId(
+      receiverKeyForExporter.publicKey,
+    );
     const { key2: receiverKeyForGifter } = gifterReceiverSession;
     const handoffCount = 0n;
     /** @type {HandoffReceive} */
     const handoffReceive = {
       type: 'desc:handoff-receive',
       receivingSession: exporterReceiverSessionId,
-      receivingSide: receiverKeyForExporter.publicKey.bytes,
+      receivingSide: receiverPeerIdForExporter,
       handoffCount,
       signedGive,
     };
@@ -106,7 +109,7 @@ test('makeWithdrawGiftDescriptor', t => {
       signedGive,
       handoffCount,
       exporterReceiverSessionId,
-      receiverKeyForExporter.publicKey,
+      receiverPeerIdForExporter,
       receiverKeyForGifter,
     );
     const signedReceiveIsValid = receiverKeyForGifter.publicKey.verify(