Sponge Class Reference

#include <sponge.h>

Inheritance diagram for Sponge:

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Collaboration diagram for Sponge:

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List of all members.

Public Member Functions
	Sponge (Transformation *aF, unsigned int aCapacity)
void	absorb (const UINT8 *input, unsigned int lengthInBits)
virtual void	pad ()
void	squeeze (UINT8 *output, unsigned int desiredLengthInBits)
unsigned int	getCapacity ()
unsigned int	getRate ()
virtual string	getDescription () const
Protected Member Functions
void	padCurrentBlock (unsigned int desiredLengthFactor)
void	absorbCurrentBlock ()
void	flushAndSwitchToSqueezingPhase ()
void	squeezeIntoCurrentBlock ()
Protected Attributes
Transformation *	f
unsigned int	capacity
unsigned int	rate
bool	squeezing
bool	validInput
auto_ptr< UINT8 >	state
deque< UINT8 >	currentBlock
unsigned int	bitsInCurrentBlock
Friends
ostream &	operator<< (ostream &a, const Sponge &sponge)

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Detailed Description

Class implementing the sponge construction. This class uses a given transformation (inherited from class Transformation or Permutation). The following restrictions are made:

• the rate must be a multiple of 8 bits;
• the input message can have any length (not necessarily a multiple of 8), but all calls to absorb() except the last one must give a multiple of 8 bits;
• the output stream can be given per byte only.

The capacity and the function width can have any value, provided that the rate is a multiple of 8 bits.

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Constructor & Destructor Documentation

Sponge::Sponge	(	Transformation *	aF,
		unsigned int	aCapacity
	)

The constructor. The transformation and capacity are given to the constructor, while the rate is computed from the function width and the requested capacity. The rate must be a multiple of 8. The sponge construction is set to the absorbing phase.

Parameters:

	aF	A pointer to the transformation used in the sponge construction.
	aCapacity	The desired value of the capacity.

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Member Function Documentation

void Sponge::absorb	(	const UINT8 *	input,
		unsigned int	lengthInBits
	)

Method that absorbs data. The data is given as a sequence of bytes. Within each byte, the bits are understood to be ordered from the least significant bit to the most significant bit. The last incomplete block is kept in attribute currentBlock.

Precondition:

This function must be used in the absorbing phase only.

Parameters:

	input	The data to absorb. When lengthInBits is not a multiple of 8, the last bits of data must be in the least significant bits of the last byte.
	lengthInBits	The length in bits of the data provided in input. When lengthInBits is not a multiple of 8, this function can no longer be used.

void Sponge::pad

(

)

[virtual]

Method to pad the data absorbed so far. By default, it calls padCurrentBlock(rate), but it can be overridden to provide other valid padding methods.

Precondition:

This function must be used in the absorbing phase only.

Reimplemented in Keccak.

void Sponge::squeeze	(	UINT8 *	output,
		unsigned int	desiredLengthInBits
	)

Method to extract data from the squeezing phase. If in the absorbing phase, this function also switches to the squeezing phase.

Parameters:

	output	The buffer where to store the squeezed data.
	desiredLengthInBits	The length in bits of the output. It must be a multiple of 8.

unsigned int Sponge::getCapacity

(

)

Method that returns the capacity of the sponge function.

unsigned int Sponge::getRate

(

)

Method that returns the rate of the sponge function.

string Sponge::getDescription

(

)

const [virtual]

Method that returns a string with a description of itself.

Reimplemented in Keccak.

void Sponge::padCurrentBlock

(

unsigned int

desiredLengthFactor

)

[protected]

Internal method to pad the data absorbed so far, by applying the simple padding. It appends a single bit 1, then the smallest number of bits 0 such that the data absorbed so far have a length that is a multiple of desiredLengthFactor.

Parameters:

desiredLengthFactor

The number of bits that divides the length of currentBlock after padding. It must be a strictly positive multiple of 8, and it must divide rate.

Precondition:

This function must be used in the absorbing phase only.

desiredLengthFactor must be a strictly positive multiple of 8, and it must divide rate.

void Sponge::absorbCurrentBlock

(

)

[protected]

Internal method that does the actual absorbing of the whole block in currentBlock. This method is called only when bitsInCurrentBlock is equal to the rate.

void Sponge::flushAndSwitchToSqueezingPhase

(

)

[protected]

Internal method that absorbs the data still in currentBlock, and then switches the sponge function to the squeezing phase.

void Sponge::squeezeIntoCurrentBlock

(

)

[protected]

Internal method that does the actual squeezing and stores the whole squeezed block into currentBlock.

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Friends And Related Function Documentation

ostream& operator<<	(	ostream &	a,
		const Sponge &	sponge
	)			[friend]

Method that prints a brief description of the sponge function.

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Member Data Documentation

Transformation* Sponge::f [protected]

The transformation (or permutation) used by the sponge construction. The memory allocated by f is assumed to belong to the caller; this class does not free the allocated memory.

unsigned int Sponge::capacity [protected]

The capacity of the sponge construction.

unsigned int Sponge::rate [protected]

The rate of the sponge construction.

bool Sponge::squeezing [protected]

Boolean indicating whether the sponge is in the squeezing phase (true) or in the absorbing phase (false).

bool Sponge::validInput [protected]

Boolean indicating whether a valid sponge input has been absorbed.

auto_ptr<UINT8> Sponge::state [protected]

The state of the sponge construction.

deque<UINT8> Sponge::currentBlock [protected]

Buffer containing the partial block before it is absorbed or the partial block that is being squeezed.

unsigned int Sponge::bitsInCurrentBlock [protected]

Number of bits in currentBlock.

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

• sponge.h
• sponge.cpp