org.spongycastle.crypto.macs

Class SipHash

java.lang.Object

org.spongycastle.crypto.macs.SipHash

All Implemented Interfaces:

Mac

public class SipHash
extends java.lang.Object
implements Mac

Implementation of SipHash as specified in "SipHash: a fast short-input PRF", by Jean-Philippe Aumasson and Daniel J. Bernstein (https://131002.net/siphash/siphash.pdf).

"SipHash is a family of PRFs SipHash-c-d where the integer parameters c and d are the number of compression rounds and the number of finalization rounds. A compression round is identical to a finalization round and this round function is called SipRound. Given a 128-bit key k and a (possibly empty) byte string m, SipHash-c-d returns a 64-bit value..."

Field Summary

Fields

Modifier and Type	Field and Description
protected int	c
protected int	d
protected long	k0
protected long	k1
protected long	m
protected long	v0
protected long	v1
protected long	v2
protected long	v3
protected int	wordCount
protected int	wordPos

Constructor Summary

Constructors

Constructor and Description
SipHash() SipHash-2-4
SipHash(int c, int d) SipHash-c-d

Method Summary

Modifier and Type	Method and Description
protected void	applySipRounds(int n)
long	doFinal()
int	doFinal(byte[] out, int outOff) Compute the final stage of the MAC writing the output to the out parameter.
java.lang.String	getAlgorithmName() Return the name of the algorithm the MAC implements.
int	getMacSize() Return the block size for this MAC (in bytes).
void	init(CipherParameters params) Initialise the MAC.
protected void	processMessageWord()
void	reset() Reset the MAC.
protected static long	rotateLeft(long x, int n)
void	update(byte input) add a single byte to the mac for processing.
void	update(byte[] input, int offset, int length)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

c

protected final int c

d

protected final int d

k0

protected long k0

k1

protected long k1

v0

protected long v0

v1

protected long v1

v2

protected long v2

v3

protected long v3

m

protected long m

wordPos

protected int wordPos

wordCount

protected int wordCount

Constructor Detail

SipHash

public SipHash()

SipHash-2-4

SipHash

public SipHash(int c,
               int d)

SipHash-c-d

Parameters:

c - the number of compression rounds

d - the number of finalization rounds

Method Detail

getAlgorithmName

public java.lang.String getAlgorithmName()

Description copied from interface: Mac

Return the name of the algorithm the MAC implements.

Specified by:

getAlgorithmName in interface Mac

Returns:

the name of the algorithm the MAC implements.

getMacSize

public int getMacSize()

Description copied from interface: Mac

Return the block size for this MAC (in bytes).

Specified by:

getMacSize in interface Mac

Returns:

the block size for this MAC in bytes.

init

public void init(CipherParameters params)
          throws java.lang.IllegalArgumentException

Description copied from interface: Mac

Initialise the MAC.

Specified by:

init in interface Mac

Parameters:

params - the key and other data required by the MAC.

Throws:

java.lang.IllegalArgumentException - if the params argument is inappropriate.

update

public void update(byte input)
            throws java.lang.IllegalStateException

Description copied from interface: Mac

add a single byte to the mac for processing.

Specified by:

update in interface Mac

Parameters:

input - the byte to be processed.

Throws:

java.lang.IllegalStateException - if the MAC is not initialised.

update

public void update(byte[] input,
                   int offset,
                   int length)
            throws DataLengthException,
                   java.lang.IllegalStateException

Specified by:

update in interface Mac

Parameters:

input - the array containing the input.

offset - the index in the array the data begins at.

length - the length of the input starting at inOff.

Throws:

DataLengthException - if there isn't enough data in in.

java.lang.IllegalStateException - if the MAC is not initialised.

doFinal

public long doFinal()
             throws DataLengthException,
                    java.lang.IllegalStateException

Throws:

DataLengthException

java.lang.IllegalStateException

doFinal

public int doFinal(byte[] out,
                   int outOff)
            throws DataLengthException,
                   java.lang.IllegalStateException

Description copied from interface: Mac

Compute the final stage of the MAC writing the output to the out parameter.

doFinal leaves the MAC in the same state it was after the last init.

Specified by:

doFinal in interface Mac

Parameters:

out - the array the MAC is to be output to.

outOff - the offset into the out buffer the output is to start at.

Throws:

DataLengthException - if there isn't enough space in out.

java.lang.IllegalStateException - if the MAC is not initialised.

reset

public void reset()

Description copied from interface: Mac

Reset the MAC. At the end of resetting the MAC should be in the in the same state it was after the last init (if there was one).

Specified by:

reset in interface Mac

processMessageWord

protected void processMessageWord()

applySipRounds

protected void applySipRounds(int n)

rotateLeft

protected static long rotateLeft(long x,
                                 int n)