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Beaufort.java
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Beaufort.java
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public class Beaufort extends Vigenere
{
// A Vigenere variant - see
// http://en.wikipedia.org/w/index.php?title=Beaufort_cipher&oldid=564005770
/*
Copyright (C) 2019 S Combes
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
private String sKey;
// ----------------------------------------------------------------------
Beaufort(String sKey) { super(sKey); this.sKey=sKey; allowable();}
// ----------------------------------------------------------------------
Beaufort(Codespace cs,String sKey) { super(cs,sKey); allowable();}
// ----------------------------------------------------------------------
void allowable() { // Is this too tight a restriction ?
if (cs.PTspace.length()%2 !=0)
throw new IllegalArgumentException("Beaufort must have even alphabet");
}
// ----------------------------------------------------------------------
private String invertedText(String text)
{
StringBuilder sb=new StringBuilder();
for (int i=0;i<text.length();i++) {
int index=(cs.PTspace.length()-cs.PTspace.indexOf(text.charAt(i)))%cs.PTspace.length();
sb.append(cs.PTspace.charAt(index));
}
return sb.toString();
}
// ----------------------------------------------------------------------
@Override
public String toString()
{ return "Beaufort Cipher with key "+sKey+super.toString();}
// ----------------------------------------------------------------------
@Override
public String decode(String text)
{ return super.encode(invertedText(text)); }
// ----------------------------------------------------------------------
@Override
public String encode(String text) { return decode(text); } // Beaufort own inverse
// ----------------------------------------------------------------------
public static void main(String [] args)
{
// example from http://practicalcryptography.com/ciphers/beaufort-cipher/
String pt="DEFENDTHEEASTWALLOFTHECASTLE";
String ct="CKMPVCPVWPIWUJOGIUAPVWRIWUUK";
Beaufort b=new Beaufort("FORTIFICATION");
if (b.knownTest(pt,ct)) System.out.println("PASS");
else System.out.println("******** FAIL ***********");
}
}