hcrypto.analyzer
Class AffineAnalyzer

java.lang.Object
  hcrypto.analyzer.CryptoAnalyzer
      hcrypto.analyzer.AffineAnalyzer

All Implemented Interfaces:

Analyzer, ExpertAnalyzer, java.lang.Runnable

public class AffineAnalyzer
extends CryptoAnalyzer
implements ExpertAnalyzer

Description: This class assumes that the text it is passed is encrypted with an Affine engine.

Field Summary

Fields inherited from class hcrypto.analyzer.CryptoAnalyzer

PERMUTATION, PLAYFAIR, RAILFENCE, SIMPLESUB

Fields inherited from interface hcrypto.analyzer.Analyzer

DECIPHER_LIMIT

Constructor Summary

AffineAnalyzer()

AffineAnalyzer(AnalyzerFrame f)

AffineAnalyzer(TextStatistics ts)

Method Summary

void	doAnalysis() This method prints an analysis of the text assuming a Affine (linear) cipher was used.
void	doAnalysis(java.lang.String text)
double	getChiSquare(java.lang.String text)
java.lang.String	getKeywordString()
java.lang.String	getReport() Part of Analyzer interface.
void	run() Part of Analyzer and Runnable interface.
void	setup(java.lang.String text) setup() initializes the text and the result string.
java.lang.String	toString() Every class should have a toString() method.

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

AffineAnalyzer

public AffineAnalyzer()

AffineAnalyzer

public AffineAnalyzer(AnalyzerFrame f)

AffineAnalyzer

public AffineAnalyzer(TextStatistics ts)
               throws java.lang.NullPointerException

Throws:

java.lang.NullPointerException

Method Detail

setup

public void setup(java.lang.String text)

Description copied from class: CryptoAnalyzer

setup() initializes the text and the result string. Note that for files containing test cryptograms, the solution is sometimes also provided following the $$$ marker.

Specified by:

setup in interface Analyzer

Overrides:

setup in class CryptoAnalyzer

run

public void run()

Description copied from class: CryptoAnalyzer

Part of Analyzer and Runnable interface. Override this method in the subclass.

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()

Description copied from class: CryptoAnalyzer

Part of Analyzer interface.

Specified by:

getReport in interface Analyzer

Overrides:

getReport in class CryptoAnalyzer

getKeywordString

public java.lang.String getKeywordString()

Specified by:

getKeywordString in interface ExpertAnalyzer

toString

public java.lang.String toString()

Description copied from class: CryptoAnalyzer

Every class should have a toString() method.

Overrides:

toString in class CryptoAnalyzer

doAnalysis

public void doAnalysis(java.lang.String text)

Specified by:

doAnalysis in interface ExpertAnalyzer

doAnalysis

public void doAnalysis()

This method prints an analysis of the text assuming a Affine (linear) cipher was used. The goal is to find the values of A and B in y = Ax + B. If we assume an alphabet of a..z, then A can take on the values 1, 3, 5, 7, 9, 11, 15, 17, 19, 21, 23, 25. These are the values for which gcd(A, 26) = 1. B can take on the values 0..25. So there are 12 x 26 = 312 possible keys. This method does an exhaustive search of these keys using Chi-square test to identify the optimum key.

getChiSquare

public double getChiSquare(java.lang.String text)