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/*
* CCM Mode
* (C) 2013 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#ifndef BOTAN_AEAD_CCM_H__
#define BOTAN_AEAD_CCM_H__
#include <botan/aead.h>
#include <botan/block_cipher.h>
#include <botan/stream_cipher.h>
#include <botan/mac.h>
namespace Botan {
/**
* Base class for CCM encryption and decryption
* @see RFC 3610
*/
class BOTAN_DLL CCM_Mode : public AEAD_Mode
{
public:
void update(secure_vector<byte>& blocks, size_t offset = 0) override;
void set_associated_data(const byte ad[], size_t ad_len) override;
std::string name() const override;
size_t update_granularity() const;
Key_Length_Specification key_spec() const override;
bool valid_nonce_length(size_t) const override;
size_t default_nonce_length() const override;
void clear() override;
size_t tag_size() const { return m_tag_size; }
protected:
const size_t BS = 16; // intrinsic to CCM definition
CCM_Mode(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(size_t len, byte out[]);
void inc(secure_vector<byte>& C);
const secure_vector<byte>& ad_buf() const { return m_ad_buf; }
secure_vector<byte>& msg_buf() { return m_msg_buf; }
secure_vector<byte> format_b0(size_t msg_size);
secure_vector<byte> format_c0();
private:
secure_vector<byte> start_raw(const byte nonce[], size_t nonce_len) override;
void key_schedule(const byte key[], size_t length) override;
const size_t m_tag_size;
const size_t m_L;
std::unique_ptr<BlockCipher> m_cipher;
secure_vector<byte> m_nonce, m_msg_buf, m_ad_buf;
};
/**
* CCM Encryption
*/
class BOTAN_DLL CCM_Encryption : 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(BlockCipher* cipher, size_t tag_size = 16, size_t L = 3) :
CCM_Mode(cipher, tag_size, L) {}
void finish(secure_vector<byte>& final_block, size_t offset = 0) override;
size_t output_length(size_t input_length) const override
{ return input_length + tag_size(); }
size_t minimum_final_size() const override { return 0; }
};
/**
* CCM Decryption
*/
class BOTAN_DLL CCM_Decryption : 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(BlockCipher* cipher, size_t tag_size = 16, size_t L = 3) :
CCM_Mode(cipher, tag_size, L) {}
void finish(secure_vector<byte>& final_block, size_t offset = 0) override;
size_t output_length(size_t input_length) const override
{
BOTAN_ASSERT(input_length > tag_size(), "Sufficient input");
return input_length - tag_size();
}
size_t minimum_final_size() const override { return tag_size(); }
};
}
#endif
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