let check_hash_key = (kh1_k2: (key_hash, key)) : (bool, key_hash) => {
  let kh1, k2 = kh1_k2;
  let kh2 : key_hash = Crypto.hash_key(k2);
  if (kh1 == kh2) {
    (true, kh2);
  }
  else {
    (false, kh2);
  }
};