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/*
* EAX 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_AEAD_EAX_H_
#define BOTAN_AEAD_EAX_H_
#include <botan/aead.h>
#include <botan/block_cipher.h>
#include <botan/stream_cipher.h>
#include <botan/mac.h>
namespace Botan {
/**
* EAX base class
*/
class EAX_Mode : public AEAD_Mode
{
public:
void set_associated_data(const uint8_t ad[], size_t ad_len) override;
std::string name() const override;
size_t update_granularity() const override;
Key_Length_Specification key_spec() const override;
// EAX supports arbitrary nonce lengths
bool valid_nonce_length(size_t) const override { return true; }
size_t tag_size() const override { return m_tag_size; }
void clear() override;
void reset() override;
protected:
/**
* @param cipher the cipher to use
* @param tag_size is how big the auth tag will be
*/
EAX_Mode(BlockCipher* cipher, size_t tag_size);
size_t block_size() const { return m_cipher->block_size(); }
size_t m_tag_size;
std::unique_ptr<BlockCipher> m_cipher;
std::unique_ptr<StreamCipher> m_ctr;
std::unique_ptr<MessageAuthenticationCode> m_cmac;
secure_vector<uint8_t> m_ad_mac;
secure_vector<uint8_t> m_nonce_mac;
private:
void start_msg(const uint8_t nonce[], size_t nonce_len) override;
void key_schedule(const uint8_t key[], size_t length) override;
};
/**
* EAX Encryption
*/
class EAX_Encryption final : public EAX_Mode
{
public:
/**
* @param cipher a 128-bit block cipher
* @param tag_size is how big the auth tag will be
*/
EAX_Encryption(BlockCipher* cipher, size_t tag_size = 0) :
EAX_Mode(cipher, tag_size) {}
size_t output_length(size_t input_length) const override
{ return input_length + tag_size(); }
size_t minimum_final_size() const override { return 0; }
size_t process(uint8_t buf[], size_t size) override;
void finish(secure_vector<uint8_t>& final_block, size_t offset = 0) override;
};
/**
* EAX Decryption
*/
class EAX_Decryption final : public EAX_Mode
{
public:
/**
* @param cipher a 128-bit block cipher
* @param tag_size is how big the auth tag will be
*/
EAX_Decryption(BlockCipher* cipher, size_t tag_size = 0) :
EAX_Mode(cipher, tag_size) {}
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(); }
size_t process(uint8_t buf[], size_t size) override;
void finish(secure_vector<uint8_t>& final_block, size_t offset = 0) override;
};
}
#endif
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