vk generation

Author: jialinli98

.pnp.cjs

@@ -23,6 +23,7 @@
   },
   "license": "MIT",
   "dependencies": {
+    "@aztec/bb.js": "3.0.0-nightly.20260102",
     "@ethereumjs/trie": "^6.2.0",
     "@iarna/toml": "^2.2.5",
     "@noir-lang/noir_js": "1.0.0-beta.18",

ethereum/oracles/package.json

@@ -19,24 +19,28 @@ Unfortunately `nargo` does not generate any of the recursion artifacts. Noir tea
 - Compiled artifact - `target/${name}.json`
   - generated from code using `nargo compile --package ${name}`
   - It's a JSON that contains [`base64`](https://en.wikipedia.org/wiki/Base64) encoded bytecode under the `.bytecode` key
-- Acir bytecode
-  - generated from **compiled artifact** by taking the bytecode and decoding it as `base64`, as **bb** expects it in plain binary form. We use a temp file for it as it's fast to generate and we only use it during **VK** generation
+  - The bytecode is gzip-compressed before base64 encoding
+- Circuit artifact for bb
+  - the **compiled artifact** is written as-is (as JSON) to a temp file
+  - **bb** expects circuit JSON format (not raw bytecode) when the file has a `.json` extension
+  - **bb** handles decompression of the gzipped bytecode field internally
 - VK - `target/${name}.vk.bin`
   - verification key is generated from **acir bytecode** by running:
     - `./bb write_vk -b ${acirPath} -o ${vkPath}`
   - We cache it in a file as it's slow to generate
 - VK.json - `target/${name}.vk.json`
-  - generated from VK by running:
-    - `./bb vk_as_fields  -k ${vkPath} -o ${vkJsonPath}`
+  - generated from VK binary files using the official @aztec/bb.js API
+  - the `vk_as_fields` CLI command was removed in newer bb versions (moved to msgpack API)
+  - we use `Barretenberg.vkAsFields()` from @aztec/bb.js to convert VK to field elements
   - JSON array that contains `vkHash` as the first element and `vkAsFields` after it
 
 ## Usage
 
 ```TS
 // Read circuit compilation artifact
 const circuit = await MonorepoCircuit.create('../../', 'get_header');
-// Generate VK - slow.
-await generateVk(circuit);
+// Generate VK - slow. Pass the full artifact, not just bytecode.
+await generateVk(circuit.artefact, circuit.vkPath(), circuit.vkAsFieldsPath());
 // Read generated VK
-const vk = await VerificationKey.create(circuit);
+const vk = await VerificationKey.create(circuit.vkAsFieldsPath());
 ```

ethereum/oracles/src/noir/circuit/README.md

@@ -11,9 +11,10 @@ export class Barretenberg {
   public async writeVK(acirPath: string, vkPath: string) {
     await $`${this.binaryPath} write_vk -b ${acirPath} -o ${vkPath}`;
   }
-  public async vkAsFields(vkPath: string, vkAsFieldsPath: string) {
-    await $`${this.binaryPath} vk_as_fields -k ${vkPath} -o ${vkAsFieldsPath}`;
-  }
+
+  // Note: vk_as_fields CLI command was removed in newer bb versions
+  // VK conversion to fields is now handled in TypeScript (see vk.ts)
+
   public async proofAsFields(vkPath: string, proofWithInputsPath: string, proofAsFieldsPath: string) {
     await $`${this.binaryPath} proof_as_fields -k ${vkPath} -p ${proofWithInputsPath} -o ${proofAsFieldsPath}`;
   }

ethereum/oracles/src/noir/circuit/barretenberg.ts

@@ -1,14 +1,76 @@
-import { readObject, withTempFile } from '../../util/file.js';
-import { writeFile } from 'fs/promises';
+import { readObject, withTempFile, writeObject } from '../../util/file.js';
+import { writeFile, readFile } from 'fs/promises';
 import { Barretenberg } from './barretenberg.js';
+import { Barretenberg as BarretenbergAPI } from '@aztec/bb.js';
+import { CompiledCircuit } from '@noir-lang/noir_js';
+import path from 'path';
 
-export async function generateVk(bytecode: string, vkPath: string, vkAsFieldsPath: string): Promise<void> {
+/**
+ * Converts binary VK files to field representation for recursive verification.
+ * Uses the official @aztec/bb.js API to convert verification keys to field elements.
+ */
+async function convertVkBinaryToFields(vkDirPath: string, vkAsFieldsPath: string): Promise<void> {
+  const vkPath = path.join(vkDirPath, 'vk');
+  const vkHashPath = path.join(vkDirPath, 'vk_hash');
+
+  // Read binary files
+  const vkBinary = await readFile(vkPath);
+  const vkHashBinary = await readFile(vkHashPath);
+
+  // Use official bb.js API to convert VK to fields
+  const api = await BarretenbergAPI.new({ threads: 1 });
+  try {
+    const result = await api.vkAsFields({ verificationKey: vkBinary });
+
+    // Convert Fr objects (Uint8Array) to hex strings
+    const vkAsFields = result.fields.map((field) => '0x' + Buffer.from(field).toString('hex'));
+
+    // Convert hash to hex string
+    const vkHash = '0x' + vkHashBinary.toString('hex');
+
+    // Write as JSON: [vkHash, ...vkAsFields]
+    await writeObject([vkHash, ...vkAsFields], vkAsFieldsPath);
+  } finally {
+    await api.destroy();
+  }
+}
+
+export async function generateVk(bytecode: string, vkPath: string, vkAsFieldsPath: string): Promise<void>;
+export async function generateVk(artifact: CompiledCircuit, vkPath: string, vkAsFieldsPath: string): Promise<void>;
+export async function generateVk(
+  bytecodeOrArtifact: string | CompiledCircuit,
+  vkPath: string,
+  vkAsFieldsPath: string
+): Promise<void> {
   return await withTempFile(async (acirPath) => {
-    await writeFile(acirPath, Buffer.from(bytecode, 'base64'));
+    let artifact: CompiledCircuit;
+
+    if (typeof bytecodeOrArtifact === 'string') {
+      // Legacy: just bytecode string - create minimal artifact
+      // bb expects circuit JSON (not raw bytecode) when file has .json extension
+      artifact = {
+        noir_version: '1.0.0',
+        hash: 0,
+        abi: { parameters: [], return_type: null, error_types: {} },
+        bytecode: bytecodeOrArtifact, // Keep compressed - bb handles decompression
+      } as any;
+    } else {
+      // New: full artifact - use as-is
+      // bb expects bytecode to remain compressed (gzipped + base64)
+      artifact = bytecodeOrArtifact;
+    }
+
+    // Write circuit JSON to temp file
+    // bb reads .json files as JSON format and decompresses bytecode internally
+    await writeFile(acirPath, JSON.stringify(artifact));
 
     const barretenberg = await Barretenberg.create();
+    // write_vk creates a directory with 'vk' and 'vk_hash' files
     await barretenberg.writeVK(acirPath, vkPath);
-    await barretenberg.vkAsFields(vkPath, vkAsFieldsPath);
+
+    // Convert binary VK files to field representation
+    // vk_as_fields CLI command was removed in newer bb, so we do it in TypeScript
+    await convertVkBinaryToFields(vkPath, vkAsFieldsPath);
   });
 }
 

ethereum/oracles/src/noir/circuit/vk.ts

@@ -2,7 +2,7 @@ import { MonorepoCircuit } from '../noir/circuit/circuit.js';
 import { VerificationKey, generateVk } from '../noir/circuit/vk.js';
 
 const circuit = await MonorepoCircuit.create('../../', 'get_storage_recursive');
-await generateVk(circuit.artefact.bytecode, circuit.vkPath(), circuit.vkAsFieldsPath());
+await generateVk(circuit.artefact, circuit.vkPath(), circuit.vkAsFieldsPath());
 const vk = await VerificationKey.create(circuit.vkAsFieldsPath());
 // eslint-disable-next-line no-console
 console.log(vk);

ethereum/oracles/src/script/generateGetStorageVK.ts

@@ -28,5 +28,8 @@
   },
   "dependencies": {
     "@changesets/cli": "^2.27.2"
+  },
+  "resolutions": {
+    "@noir-lang/noirc_abi": "1.0.0-beta.18"
   }
 }