Function toChecksumAddress

include/common.hpp:144–177

Converts a lowercase hex Ethereum address to EIP-55 checksum address

// Converts a lowercase hex Ethereum address to EIP-55 checksum address
inline std::string toChecksumAddress(const std::string &address) {
  // Remove 0x prefix if present and convert to lowercase
  std::string stripAddress = address;
  if (stripAddress.rfind("0x", 0) == 0 || stripAddress.rfind("0X", 0) == 0) {
    stripAddress = stripAddress.substr(2);
  }
  std::transform(stripAddress.begin(), stripAddress.end(), stripAddress.begin(),
                 ::tolower);

  // Validate address: must be 40 hex chars and all hex digits
  if (stripAddress.size() != 40 ||
      !std::all_of(stripAddress.begin(), stripAddress.end(), [](char c) {
        return std::isxdigit(static_cast<unsigned char>(c));
      })) {
    throw std::invalid_argument("Invalid Ethereum address: " + address);
  }

  // Keccak-256 hash of the address (no 0x prefix)
  std::vector<uint8_t> addr_bytes(stripAddress.begin(), stripAddress.end());
  Keccak keccak(Keccak::Keccak256);
  std::string hash_hex = keccak(addr_bytes.data(), addr_bytes.size());

  // Build the checksum address
  std::string checksumAddress = "0x";
  for (size_t i = 0; i < stripAddress.size(); ++i) {
    int hash_nibble = std::stoi(hash_hex.substr(i, 1), nullptr, 16);
    if (hash_nibble >= 8) {
      checksumAddress += std::toupper(stripAddress[i]);
    } else {
      checksumAddress += stripAddress[i];
    }
  }
  return checksumAddress;
}

} // namespace quip