org.cryptimeleon.craco.secretsharing.accessstructure.visitors

Class MinimalFulfillingSubsetVisitor

java.lang.Object

org.cryptimeleon.craco.secretsharing.accessstructure.visitors.MinimalFulfillingSubsetVisitor

All Implemented Interfaces:

Visitor<ComparablePair<java.lang.Integer,java.util.ArrayList<java.lang.Integer>>>

public class MinimalFulfillingSubsetVisitor
extends java.lang.Object
implements Visitor<ComparablePair<java.lang.Integer,java.util.ArrayList<java.lang.Integer>>>

Given a set of shares (with identifiers between 0 and n-1 (inclusive)), this visitor computes a minimal subset that can be used to reconstruct a shared secret.

Constructor Summary

Constructors

Constructor and Description
MinimalFulfillingSubsetVisitor(java.util.Set<java.lang.Integer> setOfShareIdentifers)

Method Summary

Modifier and Type	Method and Description
ComparablePair<java.lang.Integer,java.util.ArrayList<java.lang.Integer>>	getResultOfCurrentNode() If the threshold of the visited node is fulfilled, this method computes a pair containing the number of fulfilled leaf nodes reachable from the visited node (at most the node's threshold), as well a ArrayList containing the share identifiers of the fulfilled leaves.
MinimalFulfillingSubsetVisitor	getVisitorForNextChild() Returns a visitor for the next child.
void	putResultOfChild(ComparablePair<java.lang.Integer,java.util.ArrayList<java.lang.Integer>> result) If the given result contains a fulfilled child, numberOfFulfilledChildren is incremented, and, if the current node's threshold is reached, it is marked as fulfilled.
void	visit(TreeNode currentNode) Sets threshold to the threshold of the given tree node.

Methods inherited from class java.lang.Object

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

Constructor Detail

MinimalFulfillingSubsetVisitor

public MinimalFulfillingSubsetVisitor(java.util.Set<java.lang.Integer> setOfShareIdentifers)

Method Detail

getResultOfCurrentNode

public ComparablePair<java.lang.Integer,java.util.ArrayList<java.lang.Integer>> getResultOfCurrentNode()

If the threshold of the visited node is fulfilled, this method computes a pair containing the number of fulfilled leaf nodes reachable from the visited node (at most the node's threshold), as well a ArrayList containing the share identifiers of the fulfilled leaves. This identifies a minimal subset of shares necessary to fulfill this node.

Specified by:

getResultOfCurrentNode in interface Visitor<ComparablePair<java.lang.Integer,java.util.ArrayList<java.lang.Integer>>>

getVisitorForNextChild

public MinimalFulfillingSubsetVisitor getVisitorForNextChild()

Description copied from interface: Visitor

Returns a visitor for the next child. The resulting visitor is functionally the same, but any state that was mutated while visiting the current child may be reset.

Specified by:

getVisitorForNextChild in interface Visitor<ComparablePair<java.lang.Integer,java.util.ArrayList<java.lang.Integer>>>

Returns:

a visitor of the same kind

putResultOfChild

public void putResultOfChild(ComparablePair<java.lang.Integer,java.util.ArrayList<java.lang.Integer>> result)

If the given result contains a fulfilled child, numberOfFulfilledChildren is incremented, and, if the current node's threshold is reached, it is marked as fulfilled. Furthermore, the result is added to fulfilledChildrenInfo.

Specified by:

putResultOfChild in interface Visitor<ComparablePair<java.lang.Integer,java.util.ArrayList<java.lang.Integer>>>

Parameters:

result - the result of visiting the child of the node currently being visited

visit

public void visit(TreeNode currentNode)
           throws WrongAccessStructureException

Sets threshold to the threshold of the given tree node. If the given node is a leaf node (threshold is zero), this method additionally uses the set of share identifiers specified in this MinimalFulfillingSubsetVisitor instance to check whether one of them fulfills the share requirement of the given leaf node.

Specified by:

visit in interface Visitor<ComparablePair<java.lang.Integer,java.util.ArrayList<java.lang.Integer>>>

Parameters:

currentNode - The tree node to visit.

Throws:

WrongAccessStructureException - if an inner node in the tree has threshold 0