/*

* CBC mode

* (C) 1999-2007,2013 Jack Lloyd

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

*

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

*/

#ifndef BOTAN_MODE_CBC_H_

#define BOTAN_MODE_CBC_H_

#include <botan/block_cipher.h>

#include <botan/cipher_mode.h>

#include <botan/internal/mode_pad.h>

namespace Botan {

/**

* CBC Mode

*/

class CBC_Mode : public Cipher_Mode {

   public:

      std::string name() const final;

      size_t update_granularity() const final;

      size_t ideal_granularity() const final;

      Key_Length_Specification key_spec() const final;

      size_t default_nonce_length() const final;

      bool valid_nonce_length(size_t n) const override;

      void clear() final;

      void reset() override;

      bool has_keying_material() const final;

   protected:

      CBC_Mode(std::unique_ptr<BlockCipher> cipher, std::unique_ptr<BlockCipherModePaddingMethod> padding);

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

      const BlockCipherModePaddingMethod& padding() const {

         BOTAN_ASSERT_NONNULL(m_padding);

         return *m_padding;

      }

      size_t block_size() const { return m_block_size; }

      secure_vector<uint8_t>& state() { return m_state; }

      uint8_t* state_ptr() { return m_state.data(); }

   private:

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

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

      std::unique_ptr<BlockCipher> m_cipher;

      std::unique_ptr<BlockCipherModePaddingMethod> m_padding;

      secure_vector<uint8_t> m_state;

      size_t m_block_size;

};

/**

* CBC Encryption

*/

class CBC_Encryption : public CBC_Mode {

   public:

      /**

      * @param cipher block cipher to use

      * @param padding padding method to use

      */

      CBC_Encryption(std::unique_ptr<BlockCipher> cipher, std::unique_ptr<BlockCipherModePaddingMethod> padding) :

            CBC_Mode(std::move(cipher), std::move(padding)) {}

      size_t output_length(size_t input_length) const override;

      size_t minimum_final_size() const override;

   private:

      size_t process_msg(uint8_t buf[], size_t size) override;

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

};

/**

* CBC Encryption with ciphertext stealing (CBC-CS3 variant)

*/

class CTS_Encryption final : public CBC_Encryption {

   public:

      /**

      * @param cipher block cipher to use

      */

      explicit CTS_Encryption(std::unique_ptr<BlockCipher> cipher) : CBC_Encryption(std::move(cipher), nullptr) {}

      size_t output_length(size_t input_length) const override;

      size_t minimum_final_size() const override;

      bool valid_nonce_length(size_t n) const override;

   private:

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

};

/**

* CBC Decryption

*/

class CBC_Decryption : public CBC_Mode {

   public:

      /**

      * @param cipher block cipher to use

      * @param padding padding method to use

      */

      CBC_Decryption(std::unique_ptr<BlockCipher> cipher, std::unique_ptr<BlockCipherModePaddingMethod> padding) :

            CBC_Mode(std::move(cipher), std::move(padding)), m_tempbuf(ideal_granularity()) {}

      size_t output_length(size_t input_length) const override;

      size_t minimum_final_size() const override;

      void reset() override;

   private:

      size_t process_msg(uint8_t buf[], size_t size) override;

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

      secure_vector<uint8_t> m_tempbuf;

};

/**

* CBC Decryption with ciphertext stealing (CBC-CS3 variant)

*/

class CTS_Decryption final : public CBC_Decryption {

   public:

      /**

      * @param cipher block cipher to use

      */

      explicit CTS_Decryption(std::unique_ptr<BlockCipher> cipher) : CBC_Decryption(std::move(cipher), nullptr) {}

      size_t minimum_final_size() const override;

      bool valid_nonce_length(size_t n) const override;

   private:

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

};

}  // namespace Botan

#endif