use --output_format json

Author: jialinli98

.pnp.cjs

@@ -23,7 +23,7 @@
   },
   "license": "MIT",
   "dependencies": {
-    "@aztec/bb.js": "3.0.3",
+    "@aztec/bb.js": "4.0.0-nightly.20260128",
     "@ethereumjs/trie": "^6.2.0",
     "@iarna/toml": "^2.2.5",
     "@noir-lang/noir_js": "1.0.0-beta.18",

ethereum/oracles/package.json

@@ -29,10 +29,10 @@ Unfortunately `nargo` does not generate any of the recursion artifacts. Noir tea
     - `./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 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
+  - generated using bb CLI with `--output_format json` flag (available in v4.0.0+)
+  - command: `./bb write_vk -b ${acirPath} -o ${vkPath} --output_format json`
+  - the new JSON format includes `fields` array, `vk_hash`, and metadata (bb_version, scheme, etc.)
+  - we convert it to a JSON array with `vkHash` as the first element and `vkAsFields` after it
 
 ## Usage
 

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

@@ -1,18 +1,39 @@
 import { $ } from 'execa';
 import path from 'path';
 import os from 'os';
+import { readFile } from 'fs/promises';
+
+export interface VKJsonOutput {
+  fields: string[];
+  vk_hash: string;
+  file_kind: string;
+  bb_version: string;
+  scheme: string;
+}
+
+export interface ProofJsonOutput {
+  fields: string[];
+  vk_hash: string;
+  file_kind: string;
+  bb_version: string;
+  scheme: string;
+}
 
 export class Barretenberg {
   public static async create(): Promise<Barretenberg> {
     const binaryPath = path.join(os.homedir(), '.bb/bb');
     return new Barretenberg(binaryPath);
   }
+
   public async writeVK(acirPath: string, vkPath: string) {
     await $`${this.binaryPath} write_vk -b ${acirPath} -o ${vkPath}`;
   }
 
-  // Note: vk_as_fields CLI command was removed in newer bb versions
-  // VK conversion to fields is now handled in TypeScript
+  public async writeVKJson(acirPath: string, vkJsonPath: string): Promise<VKJsonOutput> {
+    await $`${this.binaryPath} write_vk -b ${acirPath} -o ${vkJsonPath} --output_format json`;
+    const jsonContent = await readFile(vkJsonPath, 'utf-8');
+    return JSON.parse(jsonContent) as VKJsonOutput;
+  }
 
   public async proofAsFields(vkPath: string, proofWithInputsPath: string, proofAsFieldsPath: string) {
     await $`${this.binaryPath} proof_as_fields -k ${vkPath} -p ${proofWithInputsPath} -o ${proofAsFieldsPath}`;
@@ -30,5 +51,26 @@ export class Barretenberg {
     }
   }
 
+  public async proveJson(
+    bytecodePath: string,
+    witnessPath: string,
+    proofJsonPath: string,
+    vkPath?: string,
+    cwd?: string
+  ): Promise<ProofJsonOutput> {
+    const options = cwd ? { cwd } : {};
+    if (vkPath) {
+      await $({
+        ...options
+      })`${this.binaryPath} prove -b ${bytecodePath} -w ${witnessPath} -o ${proofJsonPath} -k ${vkPath} --output_format json`;
+    } else {
+      await $({
+        ...options
+      })`${this.binaryPath} prove -b ${bytecodePath} -w ${witnessPath} -o ${proofJsonPath} --write_vk --output_format json`;
+    }
+    const jsonContent = await readFile(proofJsonPath, 'utf-8');
+    return JSON.parse(jsonContent) as ProofJsonOutput;
+  }
+
   private constructor(private binaryPath: string) {}
 }

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

@@ -1,36 +1,21 @@
-import { readObject, withTempFile, writeObject } from '../../util/file.js';
-import { writeFile, readFile } from 'fs/promises';
+import { readObject, writeObject, withTempFile } from '../../util/file.js';
+import { writeFile } 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';
 
 /**
- * Converts binary VK files to field representation for recursive verification.
- * Uses @aztec/bb.js API to convert verification keys to field elements.
+ * Converts VK to field representation using BB CLI JSON output.
+ * Uses the new --output_format json flag from BB v4.0.0+
  */
-async function convertVkBinaryToFields(vkDirPath: string, vkAsFieldsPath: string): Promise<void> {
-  const vkPath = path.join(vkDirPath, 'vk');
-  const vkHashPath = path.join(vkDirPath, 'vk_hash');
+async function generateVkAsFieldsJson(acirPath: string, vkAsFieldsPath: string): Promise<void> {
+  const barretenberg = await Barretenberg.create();
 
-  const vkBinary = await readFile(vkPath);
-  const vkHashBinary = await readFile(vkHashPath);
+  // Use new JSON output format to get VK fields directly
+  const vkJsonPath = vkAsFieldsPath + '.tmp.json';
+  const vkJson = await barretenberg.writeVKJson(acirPath, vkJsonPath);
 
-  // convert VK to fields
-  const api = await BarretenbergAPI.new({ threads: 1 });
-  try {
-    const result = await api.vkAsFields({ verificationKey: vkBinary });
-
-    // Convert Fr objects to hex strings
-    const vkAsFields = result.fields.map((field) => '0x' + Buffer.from(field).toString('hex'));
-
-    const vkHash = '0x' + vkHashBinary.toString('hex');
-
-    // write as JSON
-    await writeObject([vkHash, ...vkAsFields], vkAsFieldsPath);
-  } finally {
-    await api.destroy();
-  }
+  // Format: [vk_hash, ...vk_fields]
+  await writeObject([vkJson.vk_hash, ...vkJson.fields], vkAsFieldsPath);
 }
 
 export async function generateVk(bytecode: string, vkPath: string, vkAsFieldsPath: string): Promise<void>;
@@ -60,8 +45,8 @@ export async function generateVk(
     const barretenberg = await Barretenberg.create();
     await barretenberg.writeVK(acirPath, vkPath);
 
-    // Convert binary VK files to field representation
-    await convertVkBinaryToFields(vkPath, vkAsFieldsPath);
+    // Generate VK as fields using new JSON output format
+    await generateVkAsFieldsJson(acirPath, vkAsFieldsPath);
   });
 }
 

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

@@ -22,9 +22,9 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@aztec/bb.js@npm:3.0.3":
-  version: 3.0.3
-  resolution: "@aztec/bb.js@npm:3.0.3"
+"@aztec/bb.js@npm:4.0.0-nightly.20260128":
+  version: 4.0.0-nightly.20260128
+  resolution: "@aztec/bb.js@npm:4.0.0-nightly.20260128"
   dependencies:
     comlink: "npm:^4.4.1"
     commander: "npm:^12.1.0"
@@ -34,7 +34,7 @@ __metadata:
     tslib: "npm:^2.4.0"
   bin:
     bb: dest/node/bin/index.js
-  checksum: 10c0/8ba743fd2628fdaa531d97110caa5374b72ccce0c424061a97fd750cacae93ec77011e42e938c225165d34bb51f514bd2d4204f16411e91346a47abcf3262e0e
+  checksum: 10c0/84d96f13c73945929db4e14eaa76335fe4183c4f1a52e4f8750c20c59275f035d4406ad936c0524b003d5fdad1d177d57eb510d0a9bb9f6efacb99aa2d6930f4
   languageName: node
   linkType: hard
 
@@ -4815,7 +4815,7 @@ __metadata:
   version: 0.0.0-use.local
   resolution: "noir-ethereum-api-oracles@workspace:ethereum/oracles"
   dependencies:
-    "@aztec/bb.js": "npm:3.0.3"
+    "@aztec/bb.js": "npm:4.0.0-nightly.20260128"
     "@ethereumjs/trie": "npm:^6.2.0"
     "@iarna/toml": "npm:^2.2.5"
     "@noir-lang/noir_js": "npm:1.0.0-beta.18"