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/*
* ChaCha20Poly1305 AEAD
* (C) 2014 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef BOTAN_AEAD_CHACHA20_POLY1305_H__
#define BOTAN_AEAD_CHACHA20_POLY1305_H__
#include <botan/aead.h>
#include <botan/stream_cipher.h>
#include <botan/mac.h>
namespace Botan {
/**
* Base class
* See draft-irtf-cfrg-chacha20-poly1305-03 for specification
* If a nonce of 64 bits is used the older version described in
* draft-agl-tls-chacha20poly1305-04 is used instead.
*/
class BOTAN_DLL ChaCha20Poly1305_Mode : public AEAD_Mode
{
public:
void set_associated_data(const byte ad[], size_t ad_len) override;
std::string name() const override { return "ChaCha20Poly1305"; }
size_t update_granularity() const override { return 64; }
Key_Length_Specification key_spec() const override
{ return Key_Length_Specification(32); }
bool valid_nonce_length(size_t n) const override;
size_t tag_size() const override { return 16; }
void clear() override;
protected:
std::unique_ptr<StreamCipher> m_chacha;
std::unique_ptr<MessageAuthenticationCode> m_poly1305;
secure_vector<byte> m_ad;
size_t m_nonce_len = 0;
size_t m_ctext_len = 0;
bool cfrg_version() const { return m_nonce_len == 12; }
void update_len(size_t len);
private:
secure_vector<byte> start_raw(const byte nonce[], size_t nonce_len) override;
void key_schedule(const byte key[], size_t length) override;
};
/**
* ChaCha20Poly1305 Encryption
*/
class BOTAN_DLL ChaCha20Poly1305_Encryption : public ChaCha20Poly1305_Mode
{
public:
size_t output_length(size_t input_length) const override
{ return input_length + tag_size(); }
size_t minimum_final_size() const override { return 0; }
void update(secure_vector<byte>& blocks, size_t offset = 0) override;
void finish(secure_vector<byte>& final_block, size_t offset = 0) override;
};
/**
* ChaCha20Poly1305 Decryption
*/
class BOTAN_DLL ChaCha20Poly1305_Decryption : public ChaCha20Poly1305_Mode
{
public:
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(); }
void update(secure_vector<byte>& blocks, size_t offset = 0) override;
void finish(secure_vector<byte>& final_block, size_t offset = 0) override;
};
}
#endif
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