Verify circuit artifact integrity before sync

app/scripts/sync-circuit.mjs

@@ -7,12 +7,14 @@
 //   node scripts/sync-circuit.mjs --watch    # watch & auto-sync on change
 import { copyFileSync, existsSync, mkdirSync, watch } from "node:fs";
 import path from "node:path";
+import { spawnSync } from "node:child_process";
 import { fileURLToPath } from "node:url";
 
 const appDir = path.dirname(path.dirname(fileURLToPath(import.meta.url)));
 const repoRoot = path.join(appDir, "..");
 const buildDir = path.join(repoRoot, "circuits", "build");
 const outDir = path.join(appDir, "public", "circuits");
+const verifierPath = path.join(repoRoot, "circuits", "scripts", "verify-artifacts.mjs");
 
 const files = [
   { from: path.join(buildDir, "membership_js", "membership.wasm"), to: "membership.wasm" },
@@ -23,6 +25,16 @@ const files = [
 const isWatch = process.argv.includes("--watch");
 
 function sync() {
+  const verify = spawnSync(process.execPath, [verifierPath], {
+    cwd: repoRoot,
+    stdio: "inherit",
+  });
+
+  if (verify.status !== 0) {
+    if (!isWatch) process.exit(verify.status ?? 1);
+    return;
+  }
+
   mkdirSync(outDir, { recursive: true });
 
   let missing = false;

circuits/package.json

@@ -21,6 +21,7 @@
     "check-constants": "node scripts/check-poseidon-constants.mjs",
     "compile": "npm run check-constants && bash scripts/compile.sh",
     "setup": "bash scripts/setup.sh",
+    "verify-artifacts": "node scripts/verify-artifacts.mjs",
     "prove": "bash scripts/prove.sh",
     "test": "mocha --require tsx/cjs test/**/*.test.js --timeout 120000"
   },

circuits/scripts/setup.sh

@@ -38,12 +38,6 @@ npx --yes snarkjs zkey contribute "$BUILD/membership_0000.zkey" "$BUILD/membersh
   --name="Sharibo circuit key contribution" -v -e="$(head -c 64 /dev/urandom | base64)"
 npx --yes snarkjs zkey export verificationkey "$BUILD/membership_final.zkey" verification_key.json
 
-echo "Setup complete -> build/membership_final.zkey, verification_key.json"
-
-# ── Transcript fingerprinting ────────────────────────────────────────────────
-SNARKJS_VERSION="$(npx --yes snarkjs --version 2>&1 | head -n1 | sed 's/snarkjs@//')"
-DATE_NOW="$(date -u '+%Y-%m-%dT%H:%M:%SZ')"
-
 hash_file() {
   # Portable SHA-256: prefer sha256sum (Linux/WSL), fall back to shasum (macOS).
   if command -v sha256sum >/dev/null 2>&1; then
@@ -55,6 +49,16 @@ hash_file() {
   fi
 }
 
+hash_file verification_key.json > verification_key.json.sha256
+hash_file "$BUILD/membership_js/membership.wasm" > membership.wasm.sha256
+hash_file "$BUILD/membership_final.zkey" > membership_final.zkey.sha256
+
+echo "Setup complete -> build/membership_final.zkey, verification_key.json"
+
+# ── Transcript fingerprinting ────────────────────────────────────────────────
+SNARKJS_VERSION="$(npx --yes snarkjs --version 2>&1 | head -n1 | sed 's/snarkjs@//')"
+DATE_NOW="$(date -u '+%Y-%m-%dT%H:%M:%SZ')"
+
 HASH_VK="$(hash_file verification_key.json)"
 HASH_ZKEY="$(hash_file "$BUILD/membership_final.zkey")"
 HASH_PTAU="$(hash_file "$PTAU_FINAL")"

circuits/scripts/verify-artifacts.mjs

@@ -0,0 +1,82 @@
+import { createHash } from "node:crypto";
+import { existsSync, readFileSync } from "node:fs";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+
+const scriptDir = path.dirname(fileURLToPath(import.meta.url));
+const circuitsDir = path.resolve(scriptDir, "..");
+const fixHint = "run `npm run compile && npm run setup` in `circuits/`";
+
+const artifacts = [
+  {
+    name: "verification_key.json",
+    filePath: path.join(circuitsDir, "verification_key.json"),
+    hashPath: path.join(circuitsDir, "verification_key.json.sha256"),
+  },
+  {
+    name: "membership.wasm",
+    filePath: path.join(circuitsDir, "build", "membership_js", "membership.wasm"),
+    hashPath: path.join(circuitsDir, "membership.wasm.sha256"),
+  },
+  {
+    name: "membership_final.zkey",
+    filePath: path.join(circuitsDir, "build", "membership_final.zkey"),
+    hashPath: path.join(circuitsDir, "membership_final.zkey.sha256"),
+  },
+];
+
+function hashFile(filePath) {
+  return createHash("sha256").update(readFileSync(filePath)).digest("hex");
+}
+
+function readExpectedHash(hashPath) {
+  if (!existsSync(hashPath)) return null;
+
+  const raw = readFileSync(hashPath, "utf8").trim();
+  const match = raw.match(/[A-Fa-f0-9]{64}/);
+  if (match) return match[0].toLowerCase();
+
+  try {
+    const parsed = JSON.parse(raw);
+    const candidates = [parsed.sha256, parsed.hash, parsed["verification_key.json"], parsed["membership.wasm"], parsed["membership_final.zkey"]];
+    for (const candidate of candidates) {
+      if (typeof candidate === "string") return candidate.toLowerCase();
+    }
+  } catch {
+    // ignore malformed hash manifests and fail below with a clearer message
+  }
+
+  return null;
+}
+
+function fail(message) {
+  console.error(`Circuit artifact verification failed: ${message}`);
+  console.error(`Fix: ${fixHint}`);
+  process.exit(1);
+}
+
+const manifestPath = path.join(circuitsDir, "artifact-hashes.json");
+const manifest = existsSync(manifestPath)
+  ? JSON.parse(readFileSync(manifestPath, "utf8"))
+  : {};
+
+for (const artifact of artifacts) {
+  if (!existsSync(artifact.filePath)) {
+    fail(`${artifact.name} is missing. ${fixHint}`);
+  }
+
+  const expected = readExpectedHash(artifact.hashPath) ?? manifest[artifact.name];
+
+  if (!expected) {
+    fail(`No committed SHA-256 hash found for ${artifact.name}. ${fixHint}`);
+  }
+
+  const actual = hashFile(artifact.filePath);
+  if (actual !== expected.toLowerCase()) {
+    fail(
+      `${artifact.name} hash mismatch. Expected ${expected.toLowerCase()} but found ${actual}. ${fixHint}`,
+    );
+  }
+}
+
+console.log("Circuit artifacts verified.");

docs/troubleshooting.md

@@ -245,6 +245,36 @@ Then hard-refresh the browser tab. If it still misbehaves, delete
 
 ---
 
+## Local circuit artifacts are stale and fail verification before the app copies them
+
+**Symptom**
+
+The browser throws `InvalidProof`, but the real problem is that the local `circuits/build/`
+artifacts no longer match the committed circuit setup. This often happens after deleting and
+rebuilding the circuit without re-running the trusted setup.
+
+**Cause**
+
+`app/scripts/sync-circuit.mjs` used to copy whatever existed in `circuits/build/` without checking
+whether the `.wasm` and `.zkey` still match the committed `verification_key.json`.
+
+**Fix**
+
+```bash
+cd circuits
+npm run verify-artifacts
+```
+
+If the hashes differ, the script aborts with:
+
+```bash
+run `npm run compile && npm run setup` in `circuits/`
+```
+
+This is the safe recovery path: rebuild the circuit and re-run setup, then re-sync the app.
+
+---
+
 **Still stuck?** Re-read [`CONTRIBUTING.md`](../CONTRIBUTING.md) for the dev loop and
 the [README "Run it" section](../README.md#run-it) for the step order; open an issue if
 your symptom isn't here.