edu.wisc.cs.stego.lib
Class PPCTScanner

java.lang.Object
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  +--edu.wisc.cs.stego.Scanner
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        +--edu.wisc.cs.stego.lib.PPCTScanner

public class PPCTScanner

extends Scanner

This is a scanner which tries to locate a watermark encoded with PPCTEncoder using Planted Plane Cubic Tree algorithm. The scanner takes one input -- the size of the PPCT class and tries to locate possible watermarks based on the input.

See Also:

PPCTEncoder, PPCTLookup

Constructor Summary

protected

PPCTScanner(java.lang.String[] argv) Protected constructor.

Method Summary

static Scanner	buildScanner(java.lang.String[] args) This method build a PPCTScanner object
java.lang.String[]	scanHeap(HeapProfile heap) This method will scan the heap and try to locate the watermark represented using PPCT encoding scheme
static boolean	traverse(HObject start, java.util.HashSet cycle, java.util.LinkedList sequence, java.lang.String left, java.lang.String right, int max, boolean isLeft) This method tries to do a post order traverse starting from the root node start and it checks the validity of the PPCT tree it has built so far along the way.

Methods inherited from class java.lang.Object

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

Constructor Detail

PPCTScanner

protected PPCTScanner(java.lang.String[] argv)

Protected constructor. It requires one input, the catalan number. Technically, it is not the catalan number C(n), it is n, which is the number of nodes in the tree (not counting root and its direct decendent.

Method Detail

buildScanner

public static Scanner buildScanner(java.lang.String[] args)

This method build a PPCTScanner object

Tags copied from class: Scanner

Parameters:

params - parameters for the initialization of the new Scanner object.

Returns:

a newly constructed and initialized Scanner object.

Throws:

NoSuchMethodError - if this is not overridden by the subclass.

scanHeap

public java.lang.String[] scanHeap(HeapProfile heap)

This method will scan the heap and try to locate the watermark represented using PPCT encoding scheme

Overrides:

scanHeap in class Scanner

Tags copied from class: Scanner

Parameters:

hp - a heap in which to search for possible watermarks.

Returns:

an array of strings which are possible watermarks.

traverse

public static boolean traverse(HObject start,
                               java.util.HashSet cycle,
                               java.util.LinkedList sequence,
                               java.lang.String left,
                               java.lang.String right,
                               int max,
                               boolean isLeft)

This method tries to do a post order traverse starting from the root node start and it checks the validity of the PPCT tree it has built so far along the way. Upon finish, sequence may, or may not, contain a sequence representing a PPCT which belongs to the class C(n)

Parameters:

start - first node

cycle - all the leaves plus root node form a cycle

sequence - sequence representing the graph

left - left node

right - right node

catalan - catalan number

isLeft - searching left or right, with respect to parent node