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/*
* ChaCha20
* (C) 2014 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef BOTAN_CHACHA_H__
#define BOTAN_CHACHA_H__
#include <botan/stream_cipher.h>
namespace Botan {
/**
* DJB's ChaCha (http://cr.yp.to/chacha.html)
*/
class BOTAN_DLL ChaCha final : public StreamCipher
{
public:
StreamCipher* clone() const override { return new ChaCha(m_rounds); }
/**
* Currently only 8, 12 or 20 rounds are supported, all others
* will throw an exception
*/
ChaCha(size_t rounds);
void cipher(const byte in[], byte out[], size_t length) override;
void set_iv(const byte iv[], size_t iv_len) override;
bool valid_iv_length(size_t iv_len) const override
{ return (iv_len == 8 || iv_len == 12); }
Key_Length_Specification key_spec() const override
{
return Key_Length_Specification(16, 32, 16);
}
void clear() override;
std::string name() const override;
void seek(u64bit offset) override;
private:
void key_schedule(const byte key[], size_t key_len) override;
void incr_state_counter(size_t howmany);
void chacha_x4(byte output[64*4], u32bit state[16], size_t rounds);
#if defined(BOTAN_TARGET_SUPPORTS_SSE2)
void chacha_sse2_x4(byte output[64*4], u32bit state[16], size_t rounds);
#endif
size_t m_rounds;
secure_vector<u32bit> m_state;
secure_vector<byte> m_buffer;
size_t m_position = 0;
};
}
#endif
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