TruncatedHashTemplate< T > Class Template Reference

Construct new HashModule with smaller digest size from an existing one. More...

#include <trunhash.h>

Inheritance diagram for TruncatedHashTemplate< T >:

Public Member Functions
	TruncatedHashTemplate (T hm, unsigned int digestSize)
	Construct a TruncatedHashTemplate.
	TruncatedHashTemplate (const byte *key, size_t keyLength, unsigned int digestSize)
	Construct a TruncatedHashTemplate.
	TruncatedHashTemplate (size_t digestSize)
	Construct a TruncatedHashTemplate.
void	Restart ()
	Restart the hash.
void	Update (const byte *input, size_t length)
	Updates a hash with additional input.
unsigned int	DigestSize () const
	Provides the digest size of the hash.
void	TruncatedFinal (byte *digest, size_t digestSize)
	Computes the hash of the current message.
bool	TruncatedVerify (const byte *digest, size_t digestLength)
	Verifies the hash of the current message.
Public Member Functions inherited from HashTransformation
HashTransformation &	Ref ()
	Provides a reference to this object.
virtual byte *	CreateUpdateSpace (size_t &size)
	Request space which can be written into by the caller.
virtual void	Final (byte *digest)
	Computes the hash of the current message.
unsigned int	TagSize () const
	Provides the tag size of the hash.
virtual unsigned int	BlockSize () const
	Provides the block size of the compression function.
virtual unsigned int	OptimalBlockSize () const
	Provides the input block size most efficient for this hash.
virtual unsigned int	OptimalDataAlignment () const
	Provides input and output data alignment for optimal performance.
virtual void	CalculateDigest (byte *digest, const byte *input, size_t length)
	Updates the hash with additional input and computes the hash of the current message.
virtual bool	Verify (const byte *digest)
	Verifies the hash of the current message.
virtual bool	VerifyDigest (const byte *digest, const byte *input, size_t length)
	Updates the hash with additional input and verifies the hash of the current message.
virtual void	CalculateTruncatedDigest (byte *digest, size_t digestSize, const byte *input, size_t length)
	Updates the hash with additional input and computes the hash of the current message.
virtual bool	VerifyTruncatedDigest (const byte *digest, size_t digestLength, const byte *input, size_t length)
	Updates the hash with additional input and verifies the hash of the current message.
Public Member Functions inherited from Algorithm
	Algorithm (bool checkSelfTestStatus=true)
	Interface for all crypto algorithms.
virtual std::string	AlgorithmName () const
	Provides the name of this algorithm.
virtual std::string	AlgorithmProvider () const
	Retrieve the provider of this algorithm.
Public Member Functions inherited from Clonable
virtual Clonable *	Clone () const
	Copies this object.

Detailed Description

template<class T>
class TruncatedHashTemplate< T >

Construct new HashModule with smaller digest size from an existing one.

Template Parameters

T	HashTransformation derived class

Definition at line 31 of file trunhash.h.

Constructor & Destructor Documentation

TruncatedHashTemplate() [1/3]

template<class T >

TruncatedHashTemplate< T >::TruncatedHashTemplate ( T hm, unsigned int digestSize )

inline

Construct a TruncatedHashTemplate.

Definition at line 35 of file trunhash.h.

TruncatedHashTemplate() [2/3]

template<class T >

TruncatedHashTemplate< T >::TruncatedHashTemplate ( const byte * key, size_t keyLength, unsigned int digestSize )

inline

Construct a TruncatedHashTemplate.

Definition at line 38 of file trunhash.h.

TruncatedHashTemplate() [3/3]

template<class T >

TruncatedHashTemplate< T >::TruncatedHashTemplate ( size_t digestSize )

inline

Construct a TruncatedHashTemplate.

Definition at line 41 of file trunhash.h.

Member Function Documentation

Restart()

template<class T >

void TruncatedHashTemplate< T >::Restart ( )

inlinevirtual

Restart the hash.

Discards the current state, and restart for a new message

Reimplemented from HashTransformation.

Definition at line 44 of file trunhash.h.

Update()

template<class T >

void TruncatedHashTemplate< T >::Update ( const byte * input, size_t length )

inlinevirtual

Updates a hash with additional input.

Parameters

input	the additional input as a buffer
length	the size of the buffer, in bytes

Implements HashTransformation.

Definition at line 46 of file trunhash.h.

DigestSize()

template<class T >

unsigned int TruncatedHashTemplate< T >::DigestSize ( ) const

inlinevirtual

Provides the digest size of the hash.

Returns

the digest size of the hash.

Implements HashTransformation.

Definition at line 48 of file trunhash.h.

TruncatedFinal()

template<class T >

void TruncatedHashTemplate< T >::TruncatedFinal ( byte * digest, size_t digestSize )

inlinevirtual

Computes the hash of the current message.

Parameters

digest	a pointer to the buffer to receive the hash
digestSize	the size of the truncated digest, in bytes

TruncatedFinal() calls Final() and then copies digestSize bytes to digest. The hash is restarted the hash for the next message.

Precondition

COUNTOF(digest) <= DigestSize() or COUNTOF(digest) <= HASH::DIGESTSIZE ensures the output byte buffer is a valid size.

Implements HashTransformation.

Definition at line 49 of file trunhash.h.

TruncatedVerify()

template<class T >

bool TruncatedHashTemplate< T >::TruncatedVerify ( const byte * digest, size_t digestLength )

inlinevirtual

Verifies the hash of the current message.

Parameters

digest	a pointer to the buffer of an existing hash
digestLength	the size of the truncated hash, in bytes

Returns

true if the existing hash matches the computed hash, false otherwise

Exceptions

InvalidArgument()

if digestLength exceeds DigestSize()

TruncatedVerify() is a truncated version of Verify(). It can operate on a buffer smaller than DigestSize(). However, digestLength cannot exceed DigestSize().

Verify() performs a bitwise compare on the buffers using VerifyBufsEqual(), which is a constant time comparison function. digestLength cannot exceed DigestSize().

TruncatedVerify() restarts the hash for the next message.

Precondition

digestLength <= DigestSize() or digestLength <= HASH::DIGESTSIZE ensures the input byte buffer is a valid size.

Reimplemented from HashTransformation.

Definition at line 51 of file trunhash.h.

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The documentation for this class was generated from the following file:

• trunhash.h