mac.hpp

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#ifndef MAC_HPP
#define MAC_HPP
 
#include "cipher.hpp"
#include "util.hpp"
#include <cstddef>
#include <cstdint>


constexpr size_t MAC_TAG_SIZE = 16;
static_assert(BLOCK_SIZE == 16, "CMAC di sini mengasumsikan blok 128-bit (Rb = 0x87)");
 
namespace cmac_detail {
void dbl(const uint8_t in[16], uint8_t out[16]);
} // namespace cmac_detail

class Cmac {
public:
    explicit Cmac(const BlockCipher& cipher);
    Cmac(const BlockCipher&&) = delete; // Mencegah dangling reference ke cipher sementara
    ~Cmac();
 
    Cmac(const Cmac&) = delete;
    Cmac& operator=(const Cmac&) = delete;

    void update(const uint8_t* data, size_t len);

    void finalize(uint8_t tag[MAC_TAG_SIZE]);

    static void compute(const BlockCipher& cipher, const uint8_t* data, size_t len, uint8_t tag[MAC_TAG_SIZE]);

    static bool verify(const BlockCipher& cipher, const uint8_t* data, size_t len, const uint8_t tag[MAC_TAG_SIZE]);
 
private:
    const BlockCipher& cipher_;
    uint8_t k1_[BLOCK_SIZE];
    uint8_t k2_[BLOCK_SIZE];
    uint8_t x_[BLOCK_SIZE];
    uint8_t buf_[BLOCK_SIZE];
    size_t buf_len_{0};
 
    void process_buf();
    void reset_state();
};

struct DerivedKeys {
    uint8_t enc[KEY_SIZE]{0}; 
    uint8_t mac[KEY_SIZE]{0}; 
 
    DerivedKeys() = default;
    ~DerivedKeys() {
        util::secure_zero(enc, sizeof(enc));
        util::secure_zero(mac, sizeof(mac));
    }
    DerivedKeys(const DerivedKeys&) = default;
    DerivedKeys& operator=(const DerivedKeys&) = default;
    DerivedKeys(DerivedKeys&&) noexcept = default;
    DerivedKeys& operator=(DerivedKeys&&) noexcept = default;
};

DerivedKeys derive_keys(const BlockCipher& master_cipher);
 
#endif // MAC_HPP