source: trunk/src-cryptopp/iterhash.h

#ifndef CRYPTOPP_ITERHASH_H
#define CRYPTOPP_ITERHASH_H

#include "cryptlib.h"
#include "secblock.h"
#include "misc.h"
#include "simple.h"

NAMESPACE_BEGIN(CryptoPP)

//! \class HashInputTooLong
//! \brief Exception thrown when trying to hash more data than is allowed by a hash function
class CRYPTOPP_DLL HashInputTooLong : public InvalidDataFormat
{
public:
        explicit HashInputTooLong(const std::string &alg)
                : InvalidDataFormat("IteratedHashBase: input data exceeds maximum allowed by hash function " + alg) {}
};

//! \class IteratedHashBase
//! \brief Iterated hash base class
//! \tparam T Hash word type
//! \tparam BASE HashTransformation derived class
//! \details IteratedHashBase provides an interface for block-based iterated hashes
//! \sa HashTransformation, MessageAuthenticationCode
template <class T, class BASE>
class CRYPTOPP_NO_VTABLE IteratedHashBase : public BASE
{
public:
        typedef T HashWordType;

        //! \brief Construct an IteratedHashBase
        IteratedHashBase() : m_countLo(0), m_countHi(0) {}

        //! \brief Provides the input block size most efficient for this cipher.
        //! \return The input block size that is most efficient for the cipher
        //! \details The base class implementation returns MandatoryBlockSize().
        //! \note Optimal input length is
        //!   <tt>n * OptimalBlockSize() - GetOptimalBlockSizeUsed()</tt> for any <tt>n \> 0</tt>.
        unsigned int OptimalBlockSize() const {return this->BlockSize();}

        //! \brief Provides input and output data alignment for optimal performance.
        //! \return the input data alignment that provides optimal performance
        //! \details OptimalDataAlignment returnes the natural alignment of the hash word.
        unsigned int OptimalDataAlignment() const {return GetAlignmentOf<T>();}

        //! \brief Updates a hash with additional input
        //! \param input the additional input as a buffer
        //! \param length the size of the buffer, in bytes
        void Update(const byte *input, size_t length);

        //! \brief Requests space which can be written into by the caller
        //! \param size the requested size of the buffer
        //! \details The purpose of this method is to help avoid extra memory allocations.
        //! \details size is an \a IN and \a OUT parameter and used as a hint. When the call is made,
        //!   size is the requested size of the buffer. When the call returns, size is the size of
        //!   the array returned to the caller.
        //! \details The base class implementation sets  size to 0 and returns  NULL.
        //! \note Some objects, like ArraySink, cannot create a space because its fixed.
        byte * CreateUpdateSpace(size_t &size);

        //! \brief Restart the hash
        //! \details Discards the current state, and restart for a new message
        void Restart();

        //! \brief Computes the hash of the current message
        //! \param digest a pointer to the buffer to receive the hash
        //! \param digestSize the size of the truncated digest, in bytes
        //! \details TruncatedFinal() call Final() and then copies digestSize bytes to digest.
        //!   The hash is restarted the hash for the next message.
        void TruncatedFinal(byte *digest, size_t digestSize);

protected:
        inline T GetBitCountHi() const {return (m_countLo >> (8*sizeof(T)-3)) + (m_countHi << 3);}
        inline T GetBitCountLo() const {return m_countLo << 3;}

        void PadLastBlock(unsigned int lastBlockSize, byte padFirst=0x80);
        virtual void Init() =0;

        virtual ByteOrder GetByteOrder() const =0;
        virtual void HashEndianCorrectedBlock(const HashWordType *data) =0;
        virtual size_t HashMultipleBlocks(const T *input, size_t length);
        void HashBlock(const HashWordType *input) {HashMultipleBlocks(input, this->BlockSize());}

        virtual T* DataBuf() =0;
        virtual T* StateBuf() =0;

private:
        T m_countLo, m_countHi;
};

//! \class IteratedHash
//! \brief Iterated hash base class
//! \tparam T_HashWordType Hash word type
//! \tparam T_Endianness Endianness type of hash
//! \tparam T_BlockSize Block size of the hash
//! \tparam T_Base HashTransformation derived class
//! \details IteratedHash provides a default implementation for block-based iterated hashes
//! \sa HashTransformation, MessageAuthenticationCode
template <class T_HashWordType, class T_Endianness, unsigned int T_BlockSize, class T_Base = HashTransformation>
class CRYPTOPP_NO_VTABLE IteratedHash : public IteratedHashBase<T_HashWordType, T_Base>
{
public:
        typedef T_Endianness ByteOrderClass;
        typedef T_HashWordType HashWordType;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~IteratedHash() { }
#endif

        CRYPTOPP_CONSTANT(BLOCKSIZE = T_BlockSize)
        // BCB2006 workaround: can't use BLOCKSIZE here
        CRYPTOPP_COMPILE_ASSERT((T_BlockSize & (T_BlockSize - 1)) == 0);        // blockSize is a power of 2

        //! \brief Provides the block size of the hash
        //! \return the block size of the hash, in bytes
        //! \details BlockSize() returns <tt>T_BlockSize</tt>.
        unsigned int BlockSize() const {return T_BlockSize;}

        //! \brief Provides the byte order of the hash
        //! \returns the byte order of the hash as an enumeration
        //! \details GetByteOrder() returns <tt>T_Endianness::ToEnum()</tt>.
        //! \sa ByteOrder()
        ByteOrder GetByteOrder() const {return T_Endianness::ToEnum();}

        //! \brief Adjusts the byte ordering of the hash
        //! \param out the output buffer
        //! \param in the input buffer
        //! \param byteCount the size of the buffers, in bytes
        //! \details CorrectEndianess() calls ConditionalByteReverse() using <tt>T_Endianness</tt>.
        inline void CorrectEndianess(HashWordType *out, const HashWordType *in, size_t byteCount)
        {
                ConditionalByteReverse(T_Endianness::ToEnum(), out, in, byteCount);
        }

protected:
        T_HashWordType* DataBuf() {return this->m_data;}
        FixedSizeSecBlock<T_HashWordType, T_BlockSize/sizeof(T_HashWordType)> m_data;
};

//! \class IteratedHashWithStaticTransform
//! \brief Iterated hash with a static transformation function
//! \tparam T_HashWordType Hash word type
//! \tparam T_Endianness Endianness type of hash
//! \tparam T_BlockSize Block size of the hash
//! \tparam T_StateSize Internal state size of the hash
//! \tparam T_Transform HashTransformation derived class
//! \tparam T_DigestSize Digest size of the hash
//! \tparam T_StateAligned Flag indicating if state is 16-byte aligned
//! \sa HashTransformation, MessageAuthenticationCode
template <class T_HashWordType, class T_Endianness, unsigned int T_BlockSize, unsigned int T_StateSize, class T_Transform, unsigned int T_DigestSize = 0, bool T_StateAligned = false>
class CRYPTOPP_NO_VTABLE IteratedHashWithStaticTransform
        : public ClonableImpl<T_Transform, AlgorithmImpl<IteratedHash<T_HashWordType, T_Endianness, T_BlockSize>, T_Transform> >
{
public:

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
        virtual ~IteratedHashWithStaticTransform() { }
#endif

        CRYPTOPP_CONSTANT(DIGESTSIZE = T_DigestSize ? T_DigestSize : T_StateSize)

        //! \brief Provides the digest size of the hash
        //! \return the digest size of the hash, in bytes
        //! \details DigestSize() returns <tt>DIGESTSIZE</tt>.
        unsigned int DigestSize() const {return DIGESTSIZE;};

protected:
        IteratedHashWithStaticTransform() {this->Init();}
        void HashEndianCorrectedBlock(const T_HashWordType *data) {T_Transform::Transform(this->m_state, data);}
        void Init() {T_Transform::InitState(this->m_state);}

        T_HashWordType* StateBuf() {return this->m_state;}
        FixedSizeAlignedSecBlock<T_HashWordType, T_BlockSize/sizeof(T_HashWordType), T_StateAligned> m_state;
};

#ifndef __GNUC__
        CRYPTOPP_DLL_TEMPLATE_CLASS IteratedHashBase<word64, HashTransformation>;
        CRYPTOPP_STATIC_TEMPLATE_CLASS IteratedHashBase<word64, MessageAuthenticationCode>;

        CRYPTOPP_DLL_TEMPLATE_CLASS IteratedHashBase<word32, HashTransformation>;
        CRYPTOPP_STATIC_TEMPLATE_CLASS IteratedHashBase<word32, MessageAuthenticationCode>;
#endif

NAMESPACE_END

#endif