ccm.h

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/*
* 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