a terrible encription.

code.rs

struct Gen {
  key: i32
}
impl Iterator for Gen {
  type Item = u8;
  fn next(&mut self) -> Option<Self::Item> {
    self.key += 1;
    Some((
      ((self.key+3*3)^17)%256
    ) as u8)
  }
}

fn main() {
  use std::io;
  use std::io::Read; 
  use std::io::Write;
  let mut gen = Gen{key:0};
  for ch in io::stdin().bytes() {
    let code = ch.unwrap()^gen.next().unwrap();
    io::stdout().write(&[code]).unwrap();
  }
}