polkadot-js/common

// Copyright 2017-2024 @polkadot/util-crypto authors & contributors
// SPDX-License-Identifier: Apache-2.0

import { u8aToHex } from '@polkadot/util';

import { keccakAsU8a } from '../keccak/index.js';

function isInvalidChar (char: string, byte: number): boolean {
  return char !== (
    byte > 7
      ? char.toUpperCase()
      : char.toLowerCase()
  );
}

export function isEthereumChecksum (_address: string): boolean {
  const address = _address.replace('0x', '');
  const hash = u8aToHex(keccakAsU8a(address.toLowerCase()), -1, false);

  for (let i = 0; i < 40; i++) {
    if (isInvalidChar(address[i], parseInt(hash[i], 16))) {
      return false;
    }
  }

  return true;
}