/*

* XTS mode, from IEEE P1619

* (C) 2009,2013 Jack Lloyd

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

*

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

*/

#ifndef BOTAN_MODE_XTS_H_

#define BOTAN_MODE_XTS_H_

#include <botan/block_cipher.h>

#include <botan/cipher_mode.h>

namespace Botan {

/**

* IEEE P1619 XTS Mode

*/

class XTS_Mode : public Cipher_Mode {

   public:

      std::string name() const final;

      size_t update_granularity() const final;

      size_t ideal_granularity() const final;

      size_t minimum_final_size() const final;

      Key_Length_Specification key_spec() const final;

      size_t default_nonce_length() const final;

      bool valid_nonce_length(size_t n) const final;

      void clear() final;

      void reset() final;

      bool has_keying_material() const final;

   protected:

      explicit XTS_Mode(std::unique_ptr<BlockCipher> cipher);

      const uint8_t* tweak() const { return m_tweak.data(); }

      bool tweak_set() const { return !m_tweak.empty(); }

      size_t tweak_blocks() const { return m_tweak_blocks; }

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

      void update_tweak(size_t last_used);

      size_t cipher_block_size() const { return m_cipher_block_size; }

   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<BlockCipher> m_tweak_cipher;

      secure_vector<uint8_t> m_tweak;

      const size_t m_cipher_block_size;

      const size_t m_cipher_parallelism;

      const size_t m_tweak_blocks;

};

/**

* IEEE P1619 XTS Encryption

*/

class XTS_Encryption final : public XTS_Mode {

   public:

      /**

      * @param cipher underlying block cipher

      */

      explicit XTS_Encryption(std::unique_ptr<BlockCipher> cipher) : XTS_Mode(std::move(cipher)) {}

      size_t output_length(size_t input_length) 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;

};

/**

* IEEE P1619 XTS Decryption

*/

class XTS_Decryption final : public XTS_Mode {

   public:

      /**

      * @param cipher underlying block cipher

      */

      explicit XTS_Decryption(std::unique_ptr<BlockCipher> cipher) : XTS_Mode(std::move(cipher)) {}

      size_t output_length(size_t input_length) 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;

};

}  // namespace Botan

#endif