88 lines
4.6 KiB
C++
88 lines
4.6 KiB
C++
// authenc.h - originally written and placed in the public domain by Wei Dai
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/// \file
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/// \brief Classes for authenticated encryption modes of operation
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/// \details Authenticated encryption (AE) schemes combine confidentiality and authenticity
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/// into a single mode of operation They gained traction in the early 2000's because manually
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/// combining them was error prone for the typical developer. Around that time, the desire to
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/// authenticate but not ecrypt additional data (AAD) was also identified. When both features
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/// are available from a scheme, the system is referred to as an AEAD scheme.
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/// \details Crypto++ provides four authenticated encryption modes of operation - CCM, EAX, GCM
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/// and OCB mode. All modes derive from AuthenticatedSymmetricCipherBase() and the
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/// motivation for the API, like calling AAD a "header", can be found in Bellare,
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/// Rogaway and Wagner's <A HREF="http://web.cs.ucdavis.edu/~rogaway/papers/eax.pdf">The EAX
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/// Mode of Operation</A>. The EAX paper suggested a basic API to help standardize AEAD
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/// schemes in software and promote adoption of the modes.
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/// \sa <A HREF="http://www.cryptopp.com/wiki/Authenticated_Encryption">Authenticated
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/// Encryption</A> on the Crypto++ wiki.
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/// \since Crypto++ 5.6.0
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#ifndef CRYPTOPP_AUTHENC_H
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#define CRYPTOPP_AUTHENC_H
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#include "cryptlib.h"
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#include "secblock.h"
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NAMESPACE_BEGIN(CryptoPP)
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/// \brief Base class for authenticated encryption modes of operation
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/// \details AuthenticatedSymmetricCipherBase() serves as a base implementation for one direction
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/// (encryption or decryption) of a stream cipher or block cipher mode with authentication.
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/// \details Crypto++ provides four authenticated encryption modes of operation - CCM, EAX, GCM
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/// and OCB mode. All modes derive from AuthenticatedSymmetricCipherBase() and the
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/// motivation for the API, like calling AAD a "header", can be found in Bellare,
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/// Rogaway and Wagner's <A HREF="http://web.cs.ucdavis.edu/~rogaway/papers/eax.pdf">The EAX
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/// Mode of Operation</A>. The EAX paper suggested a basic API to help standardize AEAD
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/// schemes in software and promote adoption of the modes.
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/// \sa <A HREF="http://www.cryptopp.com/wiki/Authenticated_Encryption">Authenticated
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/// Encryption</A> on the Crypto++ wiki.
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/// \since Crypto++ 5.6.0
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class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE AuthenticatedSymmetricCipherBase : public AuthenticatedSymmetricCipher
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{
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public:
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AuthenticatedSymmetricCipherBase() : m_totalHeaderLength(0), m_totalMessageLength(0),
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m_totalFooterLength(0), m_bufferedDataLength(0), m_state(State_Start) {}
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// StreamTransformation interface
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bool IsRandomAccess() const {return false;}
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bool IsSelfInverting() const {return true;}
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void SetKey(const byte *userKey, size_t keylength, const NameValuePairs ¶ms);
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void Restart() {if (m_state > State_KeySet) m_state = State_KeySet;}
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void Resynchronize(const byte *iv, int length=-1);
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void Update(const byte *input, size_t length);
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void ProcessData(byte *outString, const byte *inString, size_t length);
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void TruncatedFinal(byte *mac, size_t macSize);
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protected:
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void UncheckedSetKey(const byte * key, unsigned int length,const CryptoPP::NameValuePairs ¶ms)
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{CRYPTOPP_UNUSED(key), CRYPTOPP_UNUSED(length), CRYPTOPP_UNUSED(params); CRYPTOPP_ASSERT(false);}
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void AuthenticateData(const byte *data, size_t len);
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const SymmetricCipher & GetSymmetricCipher() const
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{return const_cast<AuthenticatedSymmetricCipherBase *>(this)->AccessSymmetricCipher();}
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virtual SymmetricCipher & AccessSymmetricCipher() =0;
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virtual bool AuthenticationIsOnPlaintext() const =0;
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virtual unsigned int AuthenticationBlockSize() const =0;
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virtual void SetKeyWithoutResync(const byte *userKey, size_t keylength, const NameValuePairs ¶ms) =0;
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virtual void Resync(const byte *iv, size_t len) =0;
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virtual size_t AuthenticateBlocks(const byte *data, size_t len) =0;
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virtual void AuthenticateLastHeaderBlock() =0;
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virtual void AuthenticateLastConfidentialBlock() {}
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virtual void AuthenticateLastFooterBlock(byte *mac, size_t macSize) =0;
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// State_AuthUntransformed: authentication is applied to plain text (Authenticate-then-Encrypt)
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// State_AuthTransformed: authentication is applied to cipher text (Encrypt-then-Authenticate)
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enum State {State_Start, State_KeySet, State_IVSet, State_AuthUntransformed, State_AuthTransformed, State_AuthFooter};
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AlignedSecByteBlock m_buffer;
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lword m_totalHeaderLength, m_totalMessageLength, m_totalFooterLength;
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unsigned int m_bufferedDataLength;
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State m_state;
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};
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NAMESPACE_END
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#endif
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