/*
* 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/cipher_mode.h>
#include <botan/block_cipher.h>
#include <botan/mode_pad.h>

namespace Botan {

/**
* CBC Mode
*/
class BOTAN_DLL CBC_Mode : public Cipher_Mode
   {
   public:
      std::string name() const override;

      size_t update_granularity() const override;

      Key_Length_Specification key_spec() const override;

      size_t default_nonce_length() const override;

      bool valid_nonce_length(size_t n) const override;

      void clear() override;

      void reset() override;

   protected:
      CBC_Mode(BlockCipher* cipher, BlockCipherModePaddingMethod* padding);

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

      const BlockCipherModePaddingMethod& padding() const
         {
         BOTAN_ASSERT_NONNULL(m_padding);
         return *m_padding;
         }

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

      size_t block_size() const { return m_state.size(); }

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

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

      void key_schedule(const uint8_t key[], size_t length) override;

      std::unique_ptr<BlockCipher> m_cipher;
      std::unique_ptr<BlockCipherModePaddingMethod> m_padding;
      secure_vector<uint8_t> m_state;
   };

/**
* CBC Encryption
*/
class BOTAN_DLL CBC_Encryption : public CBC_Mode
   {
   public:
      /**
      * @param cipher block cipher to use
      * @param padding padding method to use
      */
      CBC_Encryption(BlockCipher* cipher, BlockCipherModePaddingMethod* padding) :
         CBC_Mode(cipher, padding) {}

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

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

      size_t output_length(size_t input_length) const override;

      size_t minimum_final_size() const override;
   };

/**
* CBC Encryption with ciphertext stealing (CBC-CS3 variant)
*/
class BOTAN_DLL CTS_Encryption final : public CBC_Encryption
   {
   public:
      /**
      * @param cipher block cipher to use
      */
      explicit CTS_Encryption(BlockCipher* cipher) : CBC_Encryption(cipher, nullptr) {}

      size_t output_length(size_t input_length) const override;

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

      size_t minimum_final_size() const override;

      bool valid_nonce_length(size_t n) const override;
   };

/**
* CBC Decryption
*/
class BOTAN_DLL CBC_Decryption : public CBC_Mode
   {
   public:
      /**
      * @param cipher block cipher to use
      * @param padding padding method to use
      */
      CBC_Decryption(BlockCipher* cipher, BlockCipherModePaddingMethod* padding) :
         CBC_Mode(cipher, padding), m_tempbuf(update_granularity()) {}

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

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

      size_t output_length(size_t input_length) const override;

      size_t minimum_final_size() const override;

      void reset() override;

   private:
      secure_vector<uint8_t> m_tempbuf;
   };

/**
* CBC Decryption with ciphertext stealing (CBC-CS3 variant)
*/
class BOTAN_DLL CTS_Decryption final : public CBC_Decryption
   {
   public:
      /**
      * @param cipher block cipher to use
      */
      explicit CTS_Decryption(BlockCipher* cipher) : CBC_Decryption(cipher, nullptr) {}

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

      size_t minimum_final_size() const override;

      bool valid_nonce_length(size_t n) const override;
   };

}

#endif