pet.orca.saph

Class Saph

java.lang.Object

pet.orca.saph.Saph

public class Saph
extends Object

Saph hasher.

This class is a configurable implementation of the Saph hashing algorithm. Parts may be added using the add methods (such as add(java.lang.String) or add(byte[])), and then finalized using the hash() method.

An example for calculating the test vector 1 would be:

 // New instance with memory size = 4 and iterations = 2
 Saph saph = new Saph(4, 2);
 saph.add("just");
 saph.add("a");
 saph.add("test");
 byte[] hash = saph.hash();
 

For convenience, add methods support return the current instance, for call chaining, so the above code may also be written as:

 byte[] hash = (new Saph(4, 2)).add("just").add("a").add("test").hash();
 

Once the hash() method has been called, no further additions are supported.

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_ITERATIONS Default number of iterations.
static int	DEFAULT_MEMORY_SIZE Default memory size, in 64-byte blocks.

Constructor Summary

Constructors

Constructor and Description
Saph() Creates a new instance with default memory and iteration count.
Saph(int memorySize, int iterations) Creates a new instance with the specified memory and iterations count.

Method Summary

Modifier and Type	Method and Description
Saph	add(byte[] part) Adds the given part to the Saph hash.
Saph	add(byte[] buffer, int offset, int length) Adds a chunk of the given buffer as a part of the Saph hash.
Saph	add(ByteBuffer part) Adds the given part to the Saph hash.
Saph	add(String part) Encodes the given string to UTF-8 and adds it to the Saph hash.
byte[]	getHash() Returns the calculated hash.
int	getIterations() Returns the configured number of iterations.
int	getMemorySize() Returns the configured memory size, in 64-byte blocks.
byte[]	hash() Calculates and returns the hash for the parts.
boolean	isCalculated() Returns true if the hash has been already calculated.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_MEMORY_SIZE

public static final int DEFAULT_MEMORY_SIZE

Default memory size, in 64-byte blocks.

See Also:

Constant Field Values

DEFAULT_ITERATIONS

public static final int DEFAULT_ITERATIONS

Default number of iterations.

See Also:

Constant Field Values

Constructor Detail

Saph

public Saph()

Creates a new instance with default memory and iteration count.

Saph

public Saph(int memorySize,
            int iterations)

Creates a new instance with the specified memory and iterations count.

Parameters:

memorySize - memory size, in 64-byte blocks

iterations - iteration count

Throws:

IllegalArgumentException - if memory or iterations are less than one

Method Detail

add

public Saph add(String part)

Encodes the given string to UTF-8 and adds it to the Saph hash.

Parameters:

part - part to add

Returns:

this instance, for chaining

Throws:

NullPointerException - if part is null

IllegalStateException - if the hash has been already calculated

add

public Saph add(byte[] part)

Adds the given part to the Saph hash.

Parameters:

part - part to add

Returns:

this instance, for chaining

Throws:

NullPointerException - if part is null

IllegalStateException - if the hash has been already calculated

add

public Saph add(byte[] buffer,
                int offset,
                int length)

Adds a chunk of the given buffer as a part of the Saph hash.

Parameters:

buffer - buffer containing the part

offset - offset of data in given buffer

length - chunk length

Returns:

this instance, for chaining

Throws:

NullPointerException - if part is null

IllegalStateException - if the hash has been already calculated

add

public Saph add(ByteBuffer part)

Adds the given part to the Saph hash.

Parameters:

part - the buffer containing the part

Returns:

this instance, for chaining

Throws:

NullPointerException - if part is null

IllegalStateException - if the hash has been already calculated

hash

public byte[] hash()

Calculates and returns the hash for the parts.

This call supports being called several times, but would be only calculated on the first call.

Returns:

the hash for the added parts

getMemorySize

public int getMemorySize()

Returns the configured memory size, in 64-byte blocks.

Returns:

the configured memory size, in 64-byte blocks.

getIterations

public int getIterations()

Returns the configured number of iterations.

Returns:

the configured number of iterations.

isCalculated

public boolean isCalculated()

Returns true if the hash has been already calculated.

Returns:

true if the hash has been already calculated.

getHash

public byte[] getHash()

Returns the calculated hash.

Returns:

the calculated hash.

Throws:

IllegalStateException - if the hash has not been yet calculated.