code: public BigInteger asBigInteger()
      {
          try
          {
              return new BigInteger(asHex, HEX_RADIX);
          }
          catch (NumberFormatException e)
          {
              throw new SecretShareException("Invalid input='" + asHex + "'", e);
          }
      }
docs: Return the original BigInteger.
  (or throw an exception if something went wrong).
  
  @return BigInteger or throw exception
  @throws SecretShareException if the hex is invalid