com.guardtime.ksi.tree

Class HashTreeBuilder

java.lang.Object

com.guardtime.ksi.tree.HashTreeBuilder

All Implemented Interfaces:

TreeBuilder<ImprintNode>

Direct Known Subclasses:

CanonicalHashTreeBuilder

public class HashTreeBuilder
extends Object
implements TreeBuilder<ImprintNode>

Hash tree (aka Merkle tree) builder implementation.

Hash tree is a tree in which every non-leaf node is labelled with the hash of the labels or values (in case of leaves) of its child nodes.

Note that HashTreeBuilder works only with ImprintNode objects. Current implementation calculates the parent hash by connecting the child node values and the parent node height before hashing.

This builder can not be used multiple times.

Constructor Summary

Constructors

Constructor and Description
HashTreeBuilder() Creates a new hash tree builder with Util.DEFAULT_AGGREGATION_ALGORITHM hash algorithm.
HashTreeBuilder(HashAlgorithm algorithm) Creates a new hash tree builder with given hash algorithm.

Method Summary

Modifier and Type	Method and Description
void	add(ImprintNode... nodes) Adds a new array of child nodes to the hash tree.
void	add(ImprintNode node) Adds a new single child node to the hash tree.
void	add(ImprintNode node, IdentityMetadata metadata) Adds a new leaf with its metadata to the hash tree.
protected ImprintNode	aggregate(ImprintNode left, ImprintNode right)
ImprintNode	build() Builds the hash tree and returns the root hash of the tree.
long	calculateHeight(ImprintNode node) Calculates the height of the hash tree in case a new node would be added.
long	calculateHeight(ImprintNode node, IdentityMetadata metadata) Calculates the height of the hash tree in case a new node with metadata would be added.
protected ImprintNode	getRootNode(LinkedList<ImprintNode> heads)

Methods inherited from class java.lang.Object

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

Constructor Detail

HashTreeBuilder

public HashTreeBuilder(HashAlgorithm algorithm)

Creates a new hash tree builder with given hash algorithm.

Parameters:

algorithm - hash algorithm to be used to calculate tree node hashes.

HashTreeBuilder

public HashTreeBuilder()

Creates a new hash tree builder with Util.DEFAULT_AGGREGATION_ALGORITHM hash algorithm.

Method Detail

add

public void add(ImprintNode node)
         throws HashException

Adds a new single child node to the hash tree.

Specified by:

add in interface TreeBuilder<ImprintNode>

Parameters:

node - child node to be added.

Throws:

HashException

add

public void add(ImprintNode node,
                IdentityMetadata metadata)
         throws HashException,
                KSIException

Adds a new leaf with its metadata to the hash tree.

Specified by:

add in interface TreeBuilder<ImprintNode>

Parameters:

node - leaf node to be added, must not be null.

metadata - node's metadata, must not be null

Throws:

HashException

KSIException

calculateHeight

public long calculateHeight(ImprintNode node)
                     throws HashException

Calculates the height of the hash tree in case a new node would be added.

Specified by:

calculateHeight in interface TreeBuilder<ImprintNode>

Parameters:

node - a leaf to be added to the tree, must not be null.

Returns:

Height of the hash tree.

Throws:

HashException

calculateHeight

public long calculateHeight(ImprintNode node,
                            IdentityMetadata metadata)
                     throws HashException,
                            KSIException

Calculates the height of the hash tree in case a new node with metadata would be added.

Specified by:

calculateHeight in interface TreeBuilder<ImprintNode>

Parameters:

node - a leaf to be added to the tree, must not be null.

metadata - metadata associated with the node.

Returns:

Height of the hash tree.

Throws:

HashException

KSIException

add

public void add(ImprintNode... nodes)
         throws HashException

Adds a new array of child nodes to the hash tree.

Specified by:

add in interface TreeBuilder<ImprintNode>

Parameters:

nodes - array of nodes to be added.

Throws:

HashException

build

public ImprintNode build()
                  throws HashException

Builds the hash tree and returns the root hash of the tree.

Specified by:

build in interface TreeBuilder<ImprintNode>

Returns:

Root hash of the finished tree.

Throws:

HashException

getRootNode

protected ImprintNode getRootNode(LinkedList<ImprintNode> heads)

aggregate

protected ImprintNode aggregate(ImprintNode left,
                                ImprintNode right)
                         throws HashException

Throws:

HashException