// 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) /// \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;} std::string AlgorithmProvider() const; 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, m_nk; size_t m_idx; // Track nonce reuse; assert in debug but continue bool m_used; }; /// \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