hcrypto.analyzer
Class WordBasedAnalyzer

java.lang.Object
  hcrypto.analyzer.CryptoAnalyzer
      hcrypto.analyzer.WordBasedAnalyzer

All Implemented Interfaces:

Analyzer, java.lang.Runnable

public class WordBasedAnalyzer
extends CryptoAnalyzer

Analyzes traditional cryptograms of the sort you find in the newspaper. It assumes the text is a word-delimited cryptogram created using a simple substitution cipher. Credits: The algorithm here is based on the algorithm reported by George W. Hart in To decode short cryptograms, CACM 37(9), Sept. 1994, 102-108. At present this analyzer only works for the alphabet 'a' to 'z'. To compile and run from the TestAnalyzer application: cd ~crypto/hcryptoj/1.4/applications/testanalyzer javac -classpath ../../classes -d ../../classes ../../source/hcrypto/analyzer/NgramAnalyzer.java java -classpath ../../classes:. TestAnalyzer analyzers.NgramAnalyzer ga_paramfiles ngram.cgrams.txt

Field Summary

Fields inherited from class hcrypto.analyzer.CryptoAnalyzer

PERMUTATION, PLAYFAIR, RAILFENCE, SIMPLESUB

Fields inherited from interface hcrypto.analyzer.Analyzer

DECIPHER_LIMIT

Constructor Summary

WordBasedAnalyzer()

WordBasedAnalyzer(GaParameters params, AnalyzerFrame f)
WordBasedAnalyzer() -- this constructor is given an object containing parameter settings

Method Summary

void	doAnalysis() This method performs an analysis of the text.
java.lang.String	getReport() This method is part of the Analyzer interface.
void	init() This method is called by setup().
void	run() This method is part of the Analyzer interface.
void	setup(java.lang.String text) This method initializes the Analyzer.
java.lang.String	toString() This method returns the report generated by the analysis.

Methods inherited from class hcrypto.analyzer.CryptoAnalyzer

prettyPrint, setup, stopThread, threadIsStopped

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

WordBasedAnalyzer

public WordBasedAnalyzer(GaParameters params,
                         AnalyzerFrame f)

WordBasedAnalyzer() -- this constructor is given an object containing parameter settings

Parameters:

params - -- an object containing param1=val1 param2=val2 ...

WordBasedAnalyzer

public WordBasedAnalyzer()

Method Detail

setup

public void setup(java.lang.String text)

This method initializes the Analyzer. The text is broken into tokens that are stored in an array. Each token is associated with a pattern -- 'that' has the pattern '1231'. The tokens are sorted with those having the smallest (non empty) pattern set given preference.

Specified by:

setup in interface Analyzer

Overrides:

setup in class CryptoAnalyzer

Parameters:

text - a String pointing to the text being analyzed

init

public void init()

This method is called by setup().

run

public void run()

This method is part of the Analyzer interface. It runs the analysis.

Specified by:

run in interface Analyzer

Specified by:

run in interface java.lang.Runnable

Overrides:

run in class CryptoAnalyzer

getReport

public java.lang.String getReport()

This method is part of the Analyzer interface. It returns the report generated by the analysis.

Specified by:

getReport in interface Analyzer

Overrides:

getReport in class CryptoAnalyzer

toString

public java.lang.String toString()

This method returns the report generated by the analysis.

Overrides:

toString in class CryptoAnalyzer

doAnalysis

public void doAnalysis()

This method performs an analysis of the text. It assumes the text is a word-delimited cryptogram created using a simple substitution cipher. The anlysis is performed by a recursive backtracking search of the key space.