/*

* CCM Mode

* (C) 2013 Jack Lloyd

* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity

*

* Botan is released under the Simplified BSD License (see license.txt)

*/

#ifndef BOTAN_AEAD_CCM_H_

#define BOTAN_AEAD_CCM_H_

#include <botan/aead.h>

#include <botan/block_cipher.h>

namespace Botan {

/**

* Base class for CCM encryption and decryption

* @see RFC 3610

*/

class CCM_Mode : public AEAD_Mode {

   public:

      void set_associated_data_n(size_t idx, std::span<const uint8_t> ad) final;

      bool associated_data_requires_key() const final { return false; }

      std::string name() const final;

      size_t update_granularity() const final;

      size_t ideal_granularity() const final;

      bool requires_entire_message() const final;

      Key_Length_Specification key_spec() const final;

      bool valid_nonce_length(size_t) const final;

      size_t default_nonce_length() const final;

      void clear() final;

      void reset() final;

      size_t tag_size() const final { return m_tag_size; }

      bool has_keying_material() const final;

   protected:

      CCM_Mode(std::unique_ptr<BlockCipher> cipher, size_t tag_size, size_t L);

      size_t L() const { return m_L; }

      const BlockCipher& cipher() const { return *m_cipher; }

      void encode_length(uint64_t len, uint8_t out[]);

      static void inc(secure_vector<uint8_t>& C);

      const secure_vector<uint8_t>& ad_buf() const { return m_ad_buf; }

      secure_vector<uint8_t>& msg_buf() { return m_msg_buf; }

      secure_vector<uint8_t> format_b0(size_t msg_size);

      secure_vector<uint8_t> format_c0();

   private:

      void start_msg(const uint8_t nonce[], size_t nonce_len) final;

      size_t process_msg(uint8_t buf[], size_t sz) final;

      void key_schedule(std::span<const uint8_t> key) final;

      const size_t m_tag_size;

      const size_t m_L;

      std::unique_ptr<BlockCipher> m_cipher;

      secure_vector<uint8_t> m_nonce, m_msg_buf, m_ad_buf;

};

/**

* CCM Encryption

*/

class CCM_Encryption final : public CCM_Mode {

   public:

      /**

      * @param cipher a 128-bit block cipher

      * @param tag_size is how big the auth tag will be (even values

      *                 between 4 and 16 are accepted)

      * @param L length of L parameter. The total message length

      *           must be less than 2**L bytes, and the nonce is 15-L bytes.

      */

      CCM_Encryption(std::unique_ptr<BlockCipher> cipher, size_t tag_size = 16, size_t L = 3) :

            CCM_Mode(std::move(cipher), tag_size, L) {}

      size_t output_length(size_t input_length) const override { return input_length + tag_size(); }

      size_t minimum_final_size() const override { return 0; }

   private:

      void finish_msg(secure_vector<uint8_t>& final_block, size_t offset = 0) override;

};

/**

* CCM Decryption

*/

class CCM_Decryption final : public CCM_Mode {

   public:

      /**

      * @param cipher a 128-bit block cipher

      * @param tag_size is how big the auth tag will be (even values

      *                 between 4 and 16 are accepted)

      * @param L length of L parameter. The total message length

      *           must be less than 2**L bytes, and the nonce is 15-L bytes.

      */

      CCM_Decryption(std::unique_ptr<BlockCipher> cipher, size_t tag_size = 16, size_t L = 3) :

            CCM_Mode(std::move(cipher), tag_size, L) {}

      size_t output_length(size_t input_length) const override {

         BOTAN_ARG_CHECK(input_length >= tag_size(), "Sufficient input");

         return input_length - tag_size();

      }

      size_t minimum_final_size() const override { return tag_size(); }

   private:

      void finish_msg(secure_vector<uint8_t>& final_block, size_t offset = 0) override;

};

}  // namespace Botan

#endif