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106 lines
3.1 KiB
C++
106 lines
3.1 KiB
C++
// dmac.h - originally written and placed in the public domain by Wei Dai
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/// \file
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/// \headerfile dmac.h
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/// \brief Classes for DMAC message authentication code
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#ifndef CRYPTOPP_DMAC_H
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#define CRYPTOPP_DMAC_H
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#include "cbcmac.h"
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NAMESPACE_BEGIN(CryptoPP)
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/// \brief DMAC message authentication code base class
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/// \tparam T class derived from BlockCipherDocumentation
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template <class T>
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class CRYPTOPP_NO_VTABLE DMAC_Base : public SameKeyLengthAs<T>, public MessageAuthenticationCode
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{
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public:
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static std::string StaticAlgorithmName() {return std::string("DMAC(") + T::StaticAlgorithmName() + ")";}
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CRYPTOPP_CONSTANT(DIGESTSIZE=T::BLOCKSIZE)
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DMAC_Base() : m_subkeylength(0), m_counter(0) {}
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void UncheckedSetKey(const byte *key, unsigned int length, const NameValuePairs ¶ms);
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void Update(const byte *input, size_t length);
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void TruncatedFinal(byte *mac, size_t size);
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unsigned int DigestSize() const {return DIGESTSIZE;}
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private:
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byte *GenerateSubKeys(const byte *key, size_t keylength);
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size_t m_subkeylength;
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SecByteBlock m_subkeys;
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CBC_MAC<T> m_mac1;
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typename T::Encryption m_f2;
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unsigned int m_counter;
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};
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/// \brief DMAC message authentication code
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/// \tparam T class derived from BlockCipherDocumentation
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/// \sa <A HREF="https://eprint.iacr.org/1997/010">CBC MAC for Real-Time Data Sources (08.15.1997)</A>
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/// by Erez Petrank and Charles Rackoff
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template <class T>
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class DMAC : public MessageAuthenticationCodeFinal<DMAC_Base<T> >
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{
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public:
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/// \brief Construct a DMAC
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DMAC() {}
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/// \brief Construct a DMAC
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/// \param key a byte array used to key the cipher
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/// \param length the size of the byte array, in bytes
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DMAC(const byte *key, size_t length=DMAC_Base<T>::DEFAULT_KEYLENGTH)
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{this->SetKey(key, length);}
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};
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template <class T>
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void DMAC_Base<T>::UncheckedSetKey(const byte *key, unsigned int length, const NameValuePairs ¶ms)
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{
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m_subkeylength = T::StaticGetValidKeyLength(T::BLOCKSIZE);
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m_subkeys.resize(2*UnsignedMin((unsigned int)T::BLOCKSIZE, m_subkeylength));
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m_mac1.SetKey(GenerateSubKeys(key, length), m_subkeylength, params);
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m_f2.SetKey(m_subkeys+m_subkeys.size()/2, m_subkeylength, params);
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m_counter = 0;
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m_subkeys.resize(0);
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}
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template <class T>
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void DMAC_Base<T>::Update(const byte *input, size_t length)
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{
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m_mac1.Update(input, length);
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m_counter = (unsigned int)((m_counter + length) % T::BLOCKSIZE);
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}
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template <class T>
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void DMAC_Base<T>::TruncatedFinal(byte *mac, size_t size)
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{
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ThrowIfInvalidTruncatedSize(size);
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byte pad[T::BLOCKSIZE];
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byte padByte = byte(T::BLOCKSIZE-m_counter);
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memset(pad, padByte, padByte);
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m_mac1.Update(pad, padByte);
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m_mac1.TruncatedFinal(mac, size);
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m_f2.ProcessBlock(mac);
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m_counter = 0; // reset for next message
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}
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template <class T>
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byte *DMAC_Base<T>::GenerateSubKeys(const byte *key, size_t keylength)
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{
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typename T::Encryption cipher(key, keylength);
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memset(m_subkeys, 0, m_subkeys.size());
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cipher.ProcessBlock(m_subkeys);
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m_subkeys[m_subkeys.size()/2 + T::BLOCKSIZE - 1] = 1;
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cipher.ProcessBlock(m_subkeys+m_subkeys.size()/2);
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return m_subkeys;
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}
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NAMESPACE_END
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#endif
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