chacha.h

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// chacha.h - written and placed in the public domain by Jeffrey Walton.
//            Copyright assigned to the Crypto++ project.
//            Based on Wei Dai's Salsa20 and Bernstein's reference ChaCha
//            family implementation at http://cr.yp.to/chacha.html.


#ifndef CRYPTOPP_CHACHA_H
#define CRYPTOPP_CHACHA_H

#include "strciphr.h"
#include "secblock.h"

NAMESPACE_BEGIN(CryptoPP)

template <unsigned int R>
struct ChaCha_Info : public VariableKeyLength<32, 16, 32, 16, SimpleKeyingInterface::UNIQUE_IV, 8>, public FixedRounds<R>
{
        CRYPTOPP_STATIC_CONSTEXPR const char* StaticAlgorithmName() {
                return (R==8?"ChaCha8":(R==12?"ChaCha12":(R==20?"ChaCha20":"ChaCha")));
        }
};

template <unsigned int R>
class CRYPTOPP_NO_VTABLE ChaCha_Policy : public AdditiveCipherConcretePolicy<word32, 16>
{
protected:
        CRYPTOPP_CONSTANT(ROUNDS=FixedRounds<R>::ROUNDS)

        void CipherSetKey(const NameValuePairs &params, const byte *key, size_t length);
        void OperateKeystream(KeystreamOperation operation, byte *output, const byte *input, size_t iterationCount);
        void CipherResynchronize(byte *keystreamBuffer, const byte *IV, size_t length);
        bool CipherIsRandomAccess() const {return false;} // TODO
        void SeekToIteration(lword iterationCount);
        unsigned int GetAlignment() const;
        unsigned int GetOptimalBlockSize() const;

        FixedSizeAlignedSecBlock<word32, 16> m_state;
};

struct ChaCha8 : public ChaCha_Info<8>, public SymmetricCipherDocumentation
{
        typedef SymmetricCipherFinal<ConcretePolicyHolder<ChaCha_Policy<8>, AdditiveCipherTemplate<> >, ChaCha_Info<8> > Encryption;
        typedef Encryption Decryption;
};

struct ChaCha12 : public ChaCha_Info<12>, public SymmetricCipherDocumentation
{
        typedef SymmetricCipherFinal<ConcretePolicyHolder<ChaCha_Policy<12>, AdditiveCipherTemplate<> >, ChaCha_Info<12> > Encryption;
        typedef Encryption Decryption;
};

struct ChaCha20 : public ChaCha_Info<20>, public SymmetricCipherDocumentation
{
        typedef SymmetricCipherFinal<ConcretePolicyHolder<ChaCha_Policy<20>, AdditiveCipherTemplate<> >, ChaCha_Info<20> > Encryption;
        typedef Encryption Decryption;
};

NAMESPACE_END

#endif  // CRYPTOPP_CHACHA_H