poly1305.h

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// poly1305.h - written and placed in the public domain by Jeffrey Walton and Jean-Pierre Munch
//              Based on Andy Polyakov's Base-2^26 scalar multiplication implementation for OpenSSL.
//              Copyright assigned to the Crypto++ project


#ifndef CRYPTOPP_POLY1305_H
#define CRYPTOPP_POLY1305_H

#include "cryptlib.h"
#include "seckey.h"
#include "secblock.h"
#include "argnames.h"
#include "algparam.h"

NAMESPACE_BEGIN(CryptoPP)

template <class T>
class CRYPTOPP_NO_VTABLE Poly1305_Base : public FixedKeyLength<32, SimpleKeyingInterface::UNIQUE_IV, 16>, public MessageAuthenticationCode
{
        CRYPTOPP_COMPILE_ASSERT(T::DEFAULT_KEYLENGTH == 16);
        CRYPTOPP_COMPILE_ASSERT(T::BLOCKSIZE == 16);

public:
        static std::string StaticAlgorithmName() {return std::string("Poly1305(") + T::StaticAlgorithmName() + ")";}

        CRYPTOPP_CONSTANT(DIGESTSIZE=T::BLOCKSIZE)
        CRYPTOPP_CONSTANT(BLOCKSIZE=T::BLOCKSIZE)

        Poly1305_Base() : m_used(true) {}

        void Resynchronize (const byte *iv, int ivLength=-1);
        void GetNextIV (RandomNumberGenerator &rng, byte *iv);

        void UncheckedSetKey(const byte *key, unsigned int length, const NameValuePairs &params);
        void Update(const byte *input, size_t length);
        void TruncatedFinal(byte *mac, size_t size);
        void Restart();

        unsigned int BlockSize() const {return BLOCKSIZE;}
        unsigned int DigestSize() const {return DIGESTSIZE;}

protected:
        void HashBlocks(const byte *input, size_t length, word32 padbit);
        void HashFinal(byte *mac, size_t length);

        typename T::Encryption m_cipher;

        // Accumulated hash, clamped r-key, and encrypted nonce
        FixedSizeAlignedSecBlock<word32, 5> m_h;
        FixedSizeAlignedSecBlock<word32, 4> m_r;
        FixedSizeAlignedSecBlock<word32, 4> m_n;

        // Accumulated message bytes and index
        FixedSizeAlignedSecBlock<byte, BLOCKSIZE> m_acc;
        size_t m_idx;

        // Track nonce reuse; assert in debug but continue
        bool m_used;
};

template <class T>
class Poly1305 : public MessageAuthenticationCodeFinal<Poly1305_Base<T> >
{
public:
        CRYPTOPP_CONSTANT(DEFAULT_KEYLENGTH=Poly1305_Base<T>::DEFAULT_KEYLENGTH)

        
        Poly1305() {}

        Poly1305(const byte *key, size_t keyLength=DEFAULT_KEYLENGTH, const byte *nonce=NULL, size_t nonceLength=0)
                {this->SetKey(key, keyLength, MakeParameters(Name::IV(), ConstByteArrayParameter(nonce, nonceLength)));}
};

NAMESPACE_END

#endif  // CRYPTOPP_POLY1305_H