// 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. //! \file poly1305.h //! \brief Classes for Poly1305 message authentication code //! \details Poly1305-AES is a state-of-the-art message-authentication code suitable for a wide //! variety of applications. Poly1305-AES computes a 16-byte authenticator of a variable-length //! message, using a 16-byte AES key, a 16-byte additional key, and a 16-byte nonce. //! \details Each message must use a unique security context, which means either the key or nonce //! must be changed after each message. It can be accomplished in one of two ways. First, you //! can create a new Poly1305 object with a key and nonce each time its needed. //!
  SecByteBlock key(32), nonce(16);
//!   prng.GenerateBlock(key, key.size());
//!   prng.GenerateBlock(nonce, nonce.size());
//!
//!   Poly1305 poly1305(key, key.size(), nonce, nonce.size());
//!   poly1305.Update(...);
//!   poly1305.Final(...);
//! //! \details Second, you can create a Poly1305 object, reuse the key, and set a fresh nonce //! for each message. The second and subsequent nonces can be generated directly using a //! RandomNumberGenerator() derived class; or it can be generated using GetNextIV(). //!
  SecByteBlock key(32), nonce(16);
//!   prng.GenerateBlock(key, key.size());
//!   prng.GenerateBlock(nonce, nonce.size());
//!
//!   // First message
//!   Poly1305 poly1305(key, key.size());
//!   poly1305.Resynchronize(nonce);
//!   poly1305.Update(...);
//!   poly1305.Final(...);
//!
//!   // Second message
//!   poly1305.GetNextIV(prng, nonce);
//!   poly1305.Resynchronize(nonce);
//!   poly1305.Update(...);
//!   poly1305.Final(...);
//!   ...
//! \sa Daniel J. Bernstein The Poly1305-AES //! Message-Authentication Code (20050329) and Andy Polyakov Poly1305 Revised //! \since Crypto++ 6.0 #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) //! \class Poly1305_Base //! \brief Poly1305 message authentication code base class //! \tparam T class derived from BlockCipherDocumentation with 16-byte key and 16-byte blocksize //! \since Crypto++ 6.0 template 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_idx(0), 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 ¶ms); 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 m_h; FixedSizeAlignedSecBlock m_r; FixedSizeAlignedSecBlock m_n; // Accumulated message bytes and index FixedSizeAlignedSecBlock m_acc; size_t m_idx; // Track nonce reuse; assert in debug but continue bool m_used; }; //! \class Poly1305 //! \brief Poly1305 message authentication code //! \tparam T class derived from BlockCipherDocumentation with 16-byte key and 16-byte blocksize //! \details Poly1305-AES is a state-of-the-art message-authentication code suitable for a wide //! variety of applications. Poly1305-AES computes a 16-byte authenticator of a variable-length //! message, using a 16-byte AES key, a 16-byte additional key, and a 16-byte nonce. //! \details Each message must use a unique security context, which means either the key or nonce //! must be changed after each message. It can be accomplished in one of two ways. First, you //! can create a new Poly1305 object with a key and nonce each time its needed. //!
  SecByteBlock key(32), nonce(16);
//!   prng.GenerateBlock(key, key.size());
//!   prng.GenerateBlock(nonce, nonce.size());
//!
//!   Poly1305 poly1305(key, key.size(), nonce, nonce.size());
//!   poly1305.Update(...);
//!   poly1305.Final(...);
//! //! \details Second, you can create a Poly1305 object, reuse the key, and set a fresh nonce //! for each message. The second and subsequent nonces can be generated directly using a //! RandomNumberGenerator() derived class; or it can be generated using GetNextIV(). //!
  SecByteBlock key(32), nonce(16);
//!   prng.GenerateBlock(key, key.size());
//!   prng.GenerateBlock(nonce, nonce.size());
//!
//!   // First message
//!   Poly1305 poly1305(key, key.size());
//!   poly1305.Resynchronize(nonce);
//!   poly1305.Update(...);
//!   poly1305.Final(...);
//!
//!   // Second message
//!   poly1305.GetNextIV(prng, nonce);
//!   poly1305.Resynchronize(nonce);
//!   poly1305.Update(...);
//!   poly1305.Final(...);
//!   ...
//! \warning The Poly1305 class does not enforce a fresh nonce for each message. The source code //! will assert in debug builds to alert of nonce reuse. No action is taken in release builds. //! \sa Daniel J. Bernstein The Poly1305-AES //! Message-Authentication Code (20050329) and Andy Polyakov Poly1305 Revised //! \since Crypto++ 6.0 template class Poly1305 : public MessageAuthenticationCodeFinal > { public: CRYPTOPP_CONSTANT(DEFAULT_KEYLENGTH=Poly1305_Base::DEFAULT_KEYLENGTH) //! \brief Construct a Poly1305 Poly1305() {} //! \brief Construct a Poly1305 //! \param key a byte array used to key the cipher //! \param keyLength the size of the byte array, in bytes //! \param nonce a byte array used to key the cipher //! \param nonceLength the size of the byte array, in bytes //! \details key is the 32-byte key composed of the 16-byte AES key and the 16 additional key //! bytes used for r. //! \details Each message requires a unique security context. You can use GetNextIV() and //! Resynchronize() to set a new nonce under a key for a message. Poly1305(const byte *key, size_t keyLength=DEFAULT_KEYLENGTH, const byte *nonce=NULLPTR, size_t nonceLength=0) {this->SetKey(key, keyLength, MakeParameters(Name::IV(), ConstByteArrayParameter(nonce, nonceLength)));} }; NAMESPACE_END #endif // CRYPTOPP_POLY1305_H