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86 lines
3.6 KiB
C++
86 lines
3.6 KiB
C++
// chacha.h - written and placed in the public domain by Jeffrey Walton.
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// Based on Wei Dai's Salsa20, Botan's SSE2 implementation,
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// and Bernstein's reference ChaCha family implementation at
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// http://cr.yp.to/chacha.html.
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/// \file chacha.h
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/// \brief Classes for ChaCha8, ChaCha12 and ChaCha20 stream ciphers
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/// \details Crypto++ provides Bernstein and ECRYPT's ChaCha from <a href="http://cr.yp.to/chacha/chacha-20080128.pdf">ChaCha,
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/// a variant of Salsa20</a> (2008.01.28). Bernstein's implementation is _slightly_ different from the TLS working group's
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/// implementation for cipher suites <tt>TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256</tt>,
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/// <tt>TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256</tt>, and <tt>TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256</tt>.
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/// \since Crypto++ 5.6.4
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#ifndef CRYPTOPP_CHACHA_H
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#define CRYPTOPP_CHACHA_H
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#include "strciphr.h"
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#include "secblock.h"
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NAMESPACE_BEGIN(CryptoPP)
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/// \brief ChaCha stream cipher information
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/// \since Crypto++ 5.6.4
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struct ChaCha_Info : public VariableKeyLength<32, 16, 32, 16, SimpleKeyingInterface::UNIQUE_IV, 8>
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{
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/// \brief The algorithm name
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/// \returns the algorithm name
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/// \details StaticAlgorithmName returns the algorithm's name as a static
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/// member function.
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/// \details Bernstein named the cipher variants ChaCha8, ChaCha12 and
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/// ChaCha20. More generally, Bernstein called the family ChaCha{r}.
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/// AlgorithmName() provides the exact name once rounds are set.
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static const char* StaticAlgorithmName() {
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return "ChaCha";
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}
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};
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/// \brief ChaCha stream cipher implementation
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/// \since Crypto++ 5.6.4
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class CRYPTOPP_NO_VTABLE ChaCha_Policy : public AdditiveCipherConcretePolicy<word32, 16>
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{
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public:
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~ChaCha_Policy() {}
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ChaCha_Policy() : m_rounds(0) {}
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protected:
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void CipherSetKey(const NameValuePairs ¶ms, const byte *key, size_t length);
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void OperateKeystream(KeystreamOperation operation, byte *output, const byte *input, size_t iterationCount);
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void CipherResynchronize(byte *keystreamBuffer, const byte *IV, size_t length);
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bool CipherIsRandomAccess() const {return true;}
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void SeekToIteration(lword iterationCount);
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unsigned int GetAlignment() const;
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unsigned int GetOptimalBlockSize() const;
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std::string AlgorithmName() const;
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std::string AlgorithmProvider() const;
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// MultiBlockSafe detects a condition that can arise in the SIMD
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// implementations where we overflow one of the 32-bit state words
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// during addition in an intermediate result. Conditions to trigger
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// issue include a user seeks to around 2^32 blocks (256 GB of data).
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// https://github.com/weidai11/cryptopp/issues/732
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inline bool MultiBlockSafe(unsigned int blocks) const;
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FixedSizeAlignedSecBlock<word32, 16> m_state;
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unsigned int m_rounds;
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};
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/// \brief ChaCha stream cipher
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/// \details Bernstein and ECRYPT's ChaCha is _slightly_ different from the TLS working
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/// group's implementation for cipher suites
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/// <tt>TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256</tt>,
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/// <tt>TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256</tt>, and
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/// <tt>TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256</tt>.
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/// \sa <a href="http://cr.yp.to/chacha/chacha-20080208.pdf">ChaCha, a variant of Salsa20</a> (2008.01.28).
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/// \since Crypto++ 5.6.4
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struct ChaCha : public ChaCha_Info, public SymmetricCipherDocumentation
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{
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typedef SymmetricCipherFinal<ConcretePolicyHolder<ChaCha_Policy, AdditiveCipherTemplate<> >, ChaCha_Info > Encryption;
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typedef Encryption Decryption;
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};
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NAMESPACE_END
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#endif // CRYPTOPP_CHACHA_H
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