Enterprise C

enterprise.c

__attribute__((section(".text")))
const char fun_impl[] =
    "\x8eGlsbVdoZEV3cGw="
    "R2xhZEkgQ2FuIEg="
    "\x8d\x04\x37\xc3"
    "ZWxwIHlvdSBvdXQ="
    "VGhpcyBpcyBBU0N="
    "SUkgQXJ0ISAgICA=";

typedef int (*fun_t)(int, int);

enum fun_factory_id {
  ADD_FUNCTION = 0,
  NOT_IMPLEMENTED,
  INVALID = -1,
};

fun_t fun_factory(int x, int license_key) {
  switch (x) {
  case ADD_FUNCTION:
    unsigned offset = fun_impl[ADD_FUNCTION] ^ license_key;
    return (fun_t)(fun_impl + offset);
  default:
    break;
  }
  fun_factory(INVALID, license_key);
}

#define OUR_LICENSE_KEY (0xAE)

int main() {
  fun_t add_fun = fun_factory(ADD_FUNCTION, OUR_LICENSE_KEY);
  return add_fun(40, 2);
}