KeccakCore Class Reference

Keccak core sponge function. More...

#include <KeccakCore.h>

Public Member Functions
	KeccakCore ()
	Constructs a new Keccak sponge function. More...
	~KeccakCore ()
	Destroys this Keccak sponge function after clearing all sensitive information.
size_t	capacity () const
	Returns the capacity of the sponge function in bits. More...
void	setCapacity (size_t capacity)
	Sets the capacity of the Keccak sponge function in bits. More...
size_t	blockSize () const
	Returns the input block size for the sponge function in bytes. More...
void	reset ()
	Resets the Keccak sponge function ready for a new session. More...
void	update (const void *data, size_t size)
	Updates the Keccak sponge function with more input data. More...
void	pad (uint8_t tag)
	Pads the last block of input data to blockSize(). More...
void	extract (void *data, size_t size)
	Extracts data from the Keccak sponge function. More...
void	encrypt (void *output, const void *input, size_t size)
	Extracts data from the Keccak sponge function and uses it to encrypt a buffer. More...
void	clear ()
	Clears all sensitive data from this object.
void	setHMACKey (const void *key, size_t len, uint8_t pad, size_t hashSize)
	Sets a HMAC key for a Keccak-based hash algorithm. More...

Detailed Description

Keccak core sponge function.

KeccakCore provides the core sponge function for different capacities. It is used to implement algorithms such as SHA3 and SHAKE.

References: http://en.wikipedia.org/wiki/SHA-3

See also

SHA3_256, SHAKE256

Definition at line 29 of file KeccakCore.h.

Constructor & Destructor Documentation

KeccakCore()

KeccakCore::KeccakCore

(

)

Constructs a new Keccak sponge function.

The capacity() will initially be set to 1536, which normally won't be of much use to the caller. The constructor should be followed by a call to setCapacity() to select the capacity of interest.

Definition at line 54 of file KeccakCore.cpp.

Member Function Documentation

blockSize()

size_t KeccakCore::blockSize ( ) const

inline

Returns the input block size for the sponge function in bytes.

The block size is (1600 - capacity()) / 8.

See also

capacity()

Definition at line 38 of file KeccakCore.h.

capacity()

size_t KeccakCore::capacity

(

)

const

Returns the capacity of the sponge function in bits.

See also

setCapacity(), blockSize()

Definition at line 76 of file KeccakCore.cpp.

encrypt()

void KeccakCore::encrypt	(	void *	output,
		const void *	input,
		size_t	size
	)

Extracts data from the Keccak sponge function and uses it to encrypt a buffer.

Parameters

output	The output buffer to write to, which may be the same buffer as input. The output buffer must have at least as many bytes as the input buffer.
input	The input buffer to read from.
size	The number of bytes to encrypt.

This function extracts data from the sponge function and then XOR's it with input to generate the output.

If more than blockSize() bytes are required, the sponge function will be invoked to generate additional data.

See also

update(), reset(), extract()

Definition at line 240 of file KeccakCore.cpp.

extract()

void KeccakCore::extract	(	void *	data,
		size_t	size
	)

Extracts data from the Keccak sponge function.

Parameters

data	The data buffer to fill with extracted data.
size	The number number of bytes of extracted data that are required.

If more than blockSize() bytes are required, the sponge function will be invoked to generate additional data.

See also

update(), reset(), encrypt()

Definition at line 194 of file KeccakCore.cpp.

pad()

void KeccakCore::pad

(

uint8_t

tag

)

Pads the last block of input data to blockSize().

Parameters

tag	The tag byte to add to the padding to identify SHA3 (0x06), SHAKE (0x1F), or the plain pre-standardized version of Keccak (0x01).

The sponge function will be invoked to process the completed padding block.

See also

update(), extract()

Definition at line 167 of file KeccakCore.cpp.

reset()

void KeccakCore::reset

(

)

Resets the Keccak sponge function ready for a new session.

See also

update(), extract()

Definition at line 114 of file KeccakCore.cpp.

setCapacity()

void KeccakCore::setCapacity

(

size_t

capacity

)

Sets the capacity of the Keccak sponge function in bits.

Parameters

capacity

The capacity of the Keccak sponge function in bits which should be a multiple of 64 and between 64 and 1536.

Note

It is possible to create a sponge function with this constructor that doesn't strictly conform with the capacity and hash size constraints defined in the relevant standards. It is the responsibility of callers to only use standard parameter combinations.

See also

capacity(), blockSize()

Definition at line 94 of file KeccakCore.cpp.

setHMACKey()

void KeccakCore::setHMACKey	(	const void *	key,
		size_t	len,
		uint8_t	pad,
		size_t	hashSize
	)

Sets a HMAC key for a Keccak-based hash algorithm.

Parameters

key	Points to the HMAC key for the hashing process.
len	Length of the HMAC key in bytes.
pad	Inner (0x36) or outer (0x5C) padding value to XOR with the formatted HMAC key.
hashSize	The size of the output from the hash algorithm.

This function is intended to help classes implement Hash::resetHMAC() and Hash::finalizeHMAC() by directly formatting the HMAC key into the internal block buffer and resetting the hash.

Definition at line 293 of file KeccakCore.cpp.

update()

void KeccakCore::update	(	const void *	data,
		size_t	size
	)

Updates the Keccak sponge function with more input data.

Parameters

data	The extra input data to incorporate.
size	The size of the new data to incorporate.

This function will invoke the sponge function whenever a full blockSize() bytes of input data have been accumulated. Call pad() after the last block to finalize the input before calling extract().

See also

pad(), extract(), reset()

Definition at line 133 of file KeccakCore.cpp.

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

• KeccakCore.h
• KeccakCore.cpp