From ce3290b9ff77f6fa3d5886a261e40b4345d36759 Mon Sep 17 00:00:00 2001
From: Nils1729 <45318774+Nils1729@users.noreply.github.com>
Date: Thu, 22 May 2025 12:52:52 +0200
Subject: [PATCH] Add more checks for public inputs (#573)

---
 src/fflonk_verify.js  | 5 +++--
 src/groth16_verify.js | 4 +++-
 src/misc.js           | 7 +++++++
 src/plonk_verify.js   | 9 +++------
 4 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/src/fflonk_verify.js b/src/fflonk_verify.js
index df5f3801..70df0f11 100644
--- a/src/fflonk_verify.js
+++ b/src/fflonk_verify.js
@@ -18,6 +18,7 @@
 */
 
 import * as curves from "./curves.js";
+import { isBigIntArray } from "./misc.js";
 import { BigBuffer, utils } from "ffjavascript";
 import { Proof } from "./proof.js";
 import { Keccak256Transcript } from "./Keccak256Transcript.js";
@@ -42,8 +43,8 @@ export default async function fflonkVerify(_vk_verifier, _publicSignals, _proof,
 
     const publicSignals = unstringifyBigInts(_publicSignals);
 
-    if (publicSignals.length !== vk.nPublic) {
-        logger.error("Number of public signals does not match with vk");
+    if (!isBigIntArray(publicSignals, vk.nPublic)) {
+        logger.error("Public signals are not valid.");
         return false;
     }
 
diff --git a/src/groth16_verify.js b/src/groth16_verify.js
index ed3974e3..a951d761 100644
--- a/src/groth16_verify.js
+++ b/src/groth16_verify.js
@@ -20,6 +20,7 @@
 /* Implementation of this paper: https://eprint.iacr.org/2016/260.pdf */
 import { Scalar } from "ffjavascript";
 import * as curves from "./curves.js";
+import { isBigIntArray } from "./misc.js";
 import {  utils }   from "ffjavascript";
 const {unstringifyBigInts} = utils;
 
@@ -41,7 +42,8 @@ export default async function groth16Verify(_vk_verifier, _publicSignals, _proof
     const IC = new Uint8Array(curve.G1.F.n8*2 * publicSignals.length);
     const w = new Uint8Array(curve.Fr.n8 * publicSignals.length);
 
-    if (!publicInputsAreValid(curve, publicSignals)) {
+    if (!isBigIntArray(publicSignals, vk_verifier.nPublic) ||
+        !publicInputsAreValid(curve, publicSignals)) {
         if (logger) logger.error("Public inputs are not valid.");
         return false;
     }
diff --git a/src/misc.js b/src/misc.js
index 12804fcd..a4597800 100644
--- a/src/misc.js
+++ b/src/misc.js
@@ -259,3 +259,10 @@ export function stringifyBigIntsWithField(Fr, o) {
         return o;
     }
 }
+
+export function isBigIntArray(o, n) {
+    if (!Array.isArray(o) || o.length !== n) {
+        return false
+    }
+    return o.every(e => typeof e === "bigint")
+}
diff --git a/src/plonk_verify.js b/src/plonk_verify.js
index 5070ab00..725efc1e 100644
--- a/src/plonk_verify.js
+++ b/src/plonk_verify.js
@@ -20,6 +20,7 @@
 /* Implementation of this paper: https://eprint.iacr.org/2019/953.pdf */
 
 import * as curves from "./curves.js";
+import { isBigIntArray } from "./misc.js";
 import { utils }   from "ffjavascript";
 import { Keccak256Transcript } from "./Keccak256Transcript.js";
 import { Scalar } from "ffjavascript";
@@ -46,17 +47,13 @@ export default async function plonkVerify(_vk_verifier, _publicSignals, _proof,
         return false;
     }
 
-    if (publicSignals.length != vk_verifier.nPublic) {
-        if (logger) logger.error("Invalid number of public inputs");
-        return false;
-    }
-
     if (!evaluationsAreValid(curve, proof)) {
         if (logger) logger.error("Proof evaluations are not valid");
         return false;
     }
 
-    if (!publicInputsAreValid(curve, publicSignals)) {
+    if (!isBigIntArray(publicSignals, vk_verifier.nPublic) ||
+        !publicInputsAreValid(curve, publicSignals)) {
         if (logger) logger.error("Public inputs are not valid.");
         return false;
     }