text: #ifndef _KEY_H_
  #define _KEY_H_
  
  #include <vector>
  #include <cstdint>
  
  #include "matrix.h"
  
  class Key {
  private:
      std::vector<Matrix> keys;
  
  private:
      Matrix expand(Matrix &key);
  
  public:
      Key(std::vector<uint8_t> data);
      Matrix &operator[](int index);
      void expand(int rounds);
  };
  
  #endif