feat: add tagged note structure (#4843)

Fixes #4572

yarn-project/circuit-types/src/logs/function_l2_logs.ts

@@ -1,5 +1,5 @@
 import { sha256 } from '@aztec/foundation/crypto';
-import { Point } from '@aztec/foundation/fields';
+import { Fr, Point } from '@aztec/foundation/fields';
 import { BufferReader, prefixBufferWithLength } from '@aztec/foundation/serialize';
 
 import { randomBytes } from 'crypto';
@@ -77,7 +77,7 @@ export class FunctionL2Logs {
       if (logType === LogType.ENCRYPTED) {
         const randomEphPubKey = Point.random();
         const randomLogContent = randomBytes(144 - Point.SIZE_IN_BYTES);
-        logs.push(Buffer.concat([randomLogContent, randomEphPubKey.toBuffer()]));
+        logs.push(Buffer.concat([Fr.random().toBuffer(), randomLogContent, randomEphPubKey.toBuffer()]));
       } else {
         logs.push(UnencryptedL2Log.random().toBuffer());
       }

yarn-project/circuit-types/src/logs/l1_note_payload/index.ts

@@ -1,3 +1,4 @@
 export * from './encrypt_buffer.js';
 export * from './note.js';
 export * from './l1_note_payload.js';
+export * from './tagged_note.js';

yarn-project/circuit-types/src/logs/l1_note_payload/tagged_note.test.ts

@@ -0,0 +1,41 @@
+import { Grumpkin } from '@aztec/circuits.js/barretenberg';
+import { GrumpkinScalar, Point } from '@aztec/foundation/fields';
+
+import { L1NotePayload } from './l1_note_payload.js';
+import { TaggedNote } from './tagged_note.js';
+
+describe('L1 Note Payload', () => {
+  let grumpkin: Grumpkin;
+
+  beforeAll(() => {
+    grumpkin = new Grumpkin();
+  });
+
+  it('convert to and from buffer', () => {
+    const payload = L1NotePayload.random();
+    const taggedNote = new TaggedNote(payload);
+    const buf = taggedNote.toBuffer();
+    expect(TaggedNote.fromBuffer(buf).notePayload).toEqual(taggedNote.notePayload);
+  });
+
+  it('convert to and from encrypted buffer', () => {
+    const payload = L1NotePayload.random();
+    const taggedNote = new TaggedNote(payload);
+    const ownerPrivKey = GrumpkinScalar.random();
+    const ownerPubKey = grumpkin.mul(Grumpkin.generator, ownerPrivKey);
+    const encrypted = taggedNote.toEncryptedBuffer(ownerPubKey, grumpkin);
+    const decrypted = TaggedNote.fromEncryptedBuffer(encrypted, ownerPrivKey, grumpkin);
+    expect(decrypted).not.toBeUndefined();
+    expect(decrypted?.notePayload).toEqual(payload);
+  });
+
+  it('return undefined if unable to decrypt the encrypted buffer', () => {
+    const payload = L1NotePayload.random();
+    const taggedNote = new TaggedNote(payload);
+    const ownerPubKey = Point.random();
+    const encrypted = taggedNote.toEncryptedBuffer(ownerPubKey, grumpkin);
+    const randomPrivKey = GrumpkinScalar.random();
+    const decrypted = TaggedNote.fromEncryptedBuffer(encrypted, randomPrivKey, grumpkin);
+    expect(decrypted).toBeUndefined();
+  });
+});

yarn-project/circuit-types/src/logs/l1_note_payload/tagged_note.ts

@@ -0,0 +1,71 @@
+import { GrumpkinPrivateKey, PublicKey } from '@aztec/circuits.js';
+import { Grumpkin } from '@aztec/circuits.js/barretenberg';
+import { Fr } from '@aztec/foundation/fields';
+import { BufferReader, serializeToBuffer } from '@aztec/foundation/serialize';
+
+import { L1NotePayload } from './l1_note_payload.js';
+
+// placeholder value until tagging is implemented
+const PLACEHOLDER_TAG = new Fr(33);
+
+/**
+ * Encrypted note payload with a tag used for retrieval by clients.
+ */
+export class TaggedNote {
+  constructor(public notePayload: L1NotePayload, public tag = PLACEHOLDER_TAG) {}
+
+  /**
+   * Deserializes the TaggedNote object from a Buffer.
+   * @param buffer - Buffer or BufferReader object to deserialize.
+   * @returns An instance of TaggedNote.
+   */
+  static fromBuffer(buffer: Buffer | BufferReader): TaggedNote {
+    const reader = BufferReader.asReader(buffer);
+    const tag = Fr.fromBuffer(reader);
+    const payload = L1NotePayload.fromBuffer(reader);
+    return new TaggedNote(payload, tag);
+  }
+
+  /**
+   * Serializes the TaggedNote object into a Buffer.
+   * @returns Buffer representation of the TaggedNote object (unencrypted).
+   */
+  public toBuffer(): Buffer {
+    return serializeToBuffer(this.tag, this.notePayload);
+  }
+
+  /**
+   * Encrypt the L1NotePayload object using the owner's public key and the ephemeral private key, then attach the tag.
+   * @param ownerPubKey - Public key of the owner of the TaggedNote object.
+   * @param curve - The curve instance to use.
+   * @returns The encrypted TaggedNote object.
+   */
+  public toEncryptedBuffer(ownerPubKey: PublicKey, curve: Grumpkin): Buffer {
+    const encryptedL1NotePayload = this.notePayload.toEncryptedBuffer(ownerPubKey, curve);
+    return serializeToBuffer(this.tag, encryptedL1NotePayload);
+  }
+
+  /**
+   * Decrypts the L1NotePayload object using the owner's private key.
+   * @param data - Encrypted TaggedNote object.
+   * @param ownerPrivKey - Private key of the owner of the TaggedNote object.
+   * @param curve - The curve instance to use.
+   * @returns Instance of TaggedNote if the decryption was successful, undefined otherwise.
+   */
+  static fromEncryptedBuffer(data: Buffer, ownerPrivKey: GrumpkinPrivateKey, curve: Grumpkin): TaggedNote | undefined {
+    const reader = BufferReader.asReader(data);
+    const tag = Fr.fromBuffer(reader);
+
+    const encryptedL1NotePayload = reader.readToEnd();
+
+    const payload = L1NotePayload.fromEncryptedBuffer(encryptedL1NotePayload, ownerPrivKey, curve);
+    if (!payload) {
+      return;
+    }
+    return new TaggedNote(payload, tag);
+  }
+
+  static random(): TaggedNote {
+    return new TaggedNote(L1NotePayload.random());
+  }
+}

yarn-project/pxe/src/note_processor/note_processor.test.ts

@@ -9,6 +9,7 @@ import {
   L2BlockContext,
   L2BlockL2Logs,
   Note,
+  TaggedNote,
   TxL2Logs,
 } from '@aztec/circuit-types';
 import { Fr, MAX_NEW_NOTE_HASHES_PER_TX } from '@aztec/circuits.js';
@@ -47,8 +48,8 @@ describe('Note Processor', () => {
   const computeMockNoteHash = (note: Note) => pedersenHash(note.items.map(i => i.toBuffer()));
 
   // ownedData: [tx1, tx2, ...], the numbers in each tx represents the indices of the note hashes the account owns.
-  const createEncryptedLogsAndOwnedL1NotePayloads = (ownedData: number[][], ownedNotes: L1NotePayload[]) => {
-    const newNotes: L1NotePayload[] = [];
+  const createEncryptedLogsAndOwnedL1NotePayloads = (ownedData: number[][], ownedNotes: TaggedNote[]) => {
+    const newNotes: TaggedNote[] = [];
     const ownedL1NotePayloads: L1NotePayload[] = [];
     const txLogs: TxL2Logs[] = [];
     let usedOwnedNote = 0;
@@ -62,12 +63,13 @@ describe('Note Processor', () => {
       for (let noteIndex = 0; noteIndex < MAX_NEW_NOTE_HASHES_PER_TX; ++noteIndex) {
         const isOwner = ownedDataIndices.includes(noteIndex);
         const publicKey = isOwner ? owner.getPublicKey() : Point.random();
-        const note = (isOwner && ownedNotes[usedOwnedNote]) || L1NotePayload.random();
+        const note = (isOwner && ownedNotes[usedOwnedNote]) || TaggedNote.random();
         usedOwnedNote += note === ownedNotes[usedOwnedNote] ? 1 : 0;
         newNotes.push(note);
         if (isOwner) {
-          ownedL1NotePayloads.push(note);
+          ownedL1NotePayloads.push(note.notePayload);
         }
+        // const encryptedNote =
         const log = note.toEncryptedBuffer(publicKey, grumpkin);
         // 1 tx containing 1 function invocation containing 1 log
         logs.push(new FunctionL2Logs([log]));
@@ -80,10 +82,10 @@ describe('Note Processor', () => {
   };
 
   const mockData = (
-    ownedData: number[][],
+    ownedData: number[][], // = [[2]]
     prependedBlocks = 0,
     appendedBlocks = 0,
-    ownedNotes: L1NotePayload[] = [],
+    ownedNotes: TaggedNote[] = [], // L1NotePayload[] = [],
   ) => {
     if (ownedData.length > TXS_PER_BLOCK) {
       throw new Error(`Tx size should be less than ${TXS_PER_BLOCK}.`);
@@ -108,7 +110,7 @@ describe('Note Processor', () => {
       ownedL1NotePayloads.push(...payloads);
       for (let i = 0; i < TXS_PER_BLOCK; i++) {
         block.body.txEffects[i].newNoteHashes = newNotes
-          .map(n => computeMockNoteHash(n.note))
+          .map(n => computeMockNoteHash(n.notePayload.note))
           .slice(i * MAX_NEW_NOTE_HASHES_PER_TX, (i + 1) * MAX_NEW_NOTE_HASHES_PER_TX) as Tuple<
           Fr,
           typeof MAX_NEW_NOTE_HASHES_PER_TX
@@ -208,8 +210,8 @@ describe('Note Processor', () => {
   });
 
   it('should be able to recover two note payloads with containing the same note', async () => {
-    const note = L1NotePayload.random();
-    const note2 = L1NotePayload.random();
+    const note = TaggedNote.random(); // L1NotePayload.random();
+    const note2 = TaggedNote.random(); // L1NotePayload.random();
     // All note payloads except one have the same contract address, storage slot, and the actual note.
     const notes = [note, note, note, note2, note];
     const { blockContexts, encryptedLogsArr, ownedL1NotePayloads } = mockData([[0, 2], [], [0, 1, 3]], 0, 0, notes);

yarn-project/pxe/src/note_processor/note_processor.ts

@@ -5,6 +5,7 @@ import {
   L1NotePayload,
   L2BlockContext,
   L2BlockL2Logs,
+  TaggedNote,
 } from '@aztec/circuit-types';
 import { NoteProcessorStats } from '@aztec/circuit-types/stats';
 import { MAX_NEW_NOTE_HASHES_PER_TX, PublicKey } from '@aztec/circuits.js';
@@ -130,10 +131,11 @@ export class NoteProcessor {
         const txFunctionLogs = txLogs[indexOfTxInABlock].functionLogs;
         const excludedIndices: Set<number> = new Set();
         for (const functionLogs of txFunctionLogs) {
-          for (const logs of functionLogs.logs) {
+          for (const log of functionLogs.logs) {
             this.stats.seen++;
-            const payload = L1NotePayload.fromEncryptedBuffer(logs, privateKey, curve);
-            if (payload) {
+            const taggedNote = TaggedNote.fromEncryptedBuffer(log, privateKey, curve);
+            if (taggedNote?.notePayload) {
+              const { notePayload: payload } = taggedNote;
               // We have successfully decrypted the data.
               const txHash = blockContext.getTxHash(indexOfTxInABlock);
               try {

yarn-project/pxe/src/synchronizer/synchronizer.ts

@@ -139,15 +139,19 @@ export class Synchronizer {
 
     // filter out note processors that are already caught up
     // and sort them by the block number they are lagging behind in ascending order
-    this.noteProcessorsToCatchUp = this.noteProcessorsToCatchUp.filter(noteProcessor => {
+    const noteProcessorsToCatchUp: NoteProcessor[] = [];
+
+    this.noteProcessorsToCatchUp.forEach(noteProcessor => {
       if (noteProcessor.status.syncedToBlock >= toBlockNumber) {
         // Note processor is ahead of main sync, nothing to do
         this.noteProcessors.push(noteProcessor);
-        return false;
+      } else {
+        noteProcessorsToCatchUp.push(noteProcessor);
       }
-      return true;
     });
 
+    this.noteProcessorsToCatchUp = noteProcessorsToCatchUp;
+
     if (!this.noteProcessorsToCatchUp.length) {
       // No note processors to catch up, nothing to do here,
       // but we return true to continue with the normal flow.

yarn-project/simulator/src/client/client_execution_context.ts

@@ -5,6 +5,7 @@ import {
   L1NotePayload,
   Note,
   NoteStatus,
+  TaggedNote,
   UnencryptedL2Log,
 } from '@aztec/circuit-types';
 import {
@@ -293,7 +294,8 @@ export class ClientExecutionContext extends ViewDataOracle {
   public emitEncryptedLog(contractAddress: AztecAddress, storageSlot: Fr, noteTypeId: Fr, publicKey: Point, log: Fr[]) {
     const note = new Note(log);
     const l1NotePayload = new L1NotePayload(note, contractAddress, storageSlot, noteTypeId);
-    const encryptedNote = l1NotePayload.toEncryptedBuffer(publicKey, this.curve);
+    const taggedNote = new TaggedNote(l1NotePayload);
+    const encryptedNote = taggedNote.toEncryptedBuffer(publicKey, this.curve);
     this.encryptedLogs.push(encryptedNote);
   }