logic bug in verifyProof

[Hachikoi-the-creator]

Inside the for the concat func expects uint8Array but proof[i].data is type string
Error visible for me since I'm using TS to try and understand what is happening a little bit better
Fixed code:

  for (let i = 0; i < proof.length; i++) {
    if (proof[i].left) {
      data = concat(utf8ToBytes(proof[i].data), data);
    } else {
      data = concat(data, utf8ToBytes(proof[i].data));
    }
  }

[Hachikoi-the-creator]

nvm I broke it

[Hachikoi-the-creator]

Found a what I think could be a logic bug tho.

function verifyProof(proof, leaf, root) {
  proof = proof.map(({ data, left }) => ({
    left,
    data: hexToBytes(data),
  }));
  let data = keccak256(Buffer.from(leaf));

  for (let i = 0; i < proof.length; i++) {
    if (proof[i].left) {
      data = concat(proof[i].data, data);
    } else {
      data = concat(data, proof[i].data);
    }
  }

  return bytesToHex(data) === root;
}

since verify proof will be used in the serve and we cannot transfer uint8Arrays tru http, I modified it so the inputs use strings (hex) and in the concat we do the hextToBytes

import { keccak256 } from "ethereum-cryptography/keccak";
import { bytesToHex, hexToBytes } from "ethereum-cryptography/utils";
import { ProofVer } from "./merkleTree";

const concat = (left: Uint8Array, right: Uint8Array) =>
  keccak256(Buffer.concat([left, right]));

export function verifyProof(proof: ProofVer[], leaf: string, root: string) {
  let data: Uint8Array = keccak256(Buffer.from(leaf));

  for (let i = 0; i < proof.length; i++) {
    if (proof[i].left) {
      data = concat(hexToBytes(proof[i].data), data);
    } else {
      data = concat(data, hexToBytes(proof[i].data));
    }
  }

  return bytesToHex(data) === root;
}

that is the ts version where I was able to spot the error

Adding extra type for context

export type ProofVer = {
  left: boolean;
  data: string;
};

[mrpiper21]

Thanks, this is Very helpful.