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Bifid.java
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Bifid.java
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public class Bifid extends ClassicalCipher
{
// Conducts Bifid encryption and decryption.
/*
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/>. */
protected String key;
protected int period;
protected static final int ALL_MESSAGE=0; // Keep as 0
// ----------------------------------------------------------------------
Bifid(String word) { this(word,ALL_MESSAGE); }
// ----------------------------------------------------------------------
Bifid(String word,int period) // word can specify all 25 if required
{ this(new Codespace(Codespace.StockAlphabet.MERGED_IJ),word,period); }
// ----------------------------------------------------------------------
Bifid(Codespace cs,String word)
{
super(cs);
if (cs.PTspace.length() != 25)
throw new IllegalArgumentException("Bifid needs a 25 letter alphabet");
key=new Keyword().new Simple(cs,word).getKey();
}
// ----------------------------------------------------------------------
Bifid(Codespace cs,String word,int period)
{ this(cs,word); this.period=period; }
// ----------------------------------------------------------------------
@Override
public Bifid copyInstance(ClassicalCipher c)
{ return new Bifid(cs,((Bifid)c).key,((Bifid)c).period); }
// ----------------------------------------------------------------------
public String toString()
{ return (this.getClass().getName()+" Cipher : Key "+key+" Period = "+
((period<=0)?"ALL MESSAGE":period)+nL+super.toString());}
// ----------------------------------------------------------------------
@Override
public String encode(String PT)
{
String flat=cs.flattenToPT(PT);
if (period <= 0) return periodEncode(flat);
StringBuilder sb=new StringBuilder();
for (int i=0;i<((flat.length()-1)/period)+1;i++) {
int end=((i+1)*period > flat.length())?flat.length():(i+1)*period;
sb.append(periodEncode(flat.substring(i*period,end)));
}
return sb.toString();
}
// ----------------------------------------------------------------------
private String periodEncode(String PT)
{
int [][] coords=new int[2][PT.length()];
StringBuilder sb=new StringBuilder();
for (int i=0;i<PT.length();i++) {
int l1=key.indexOf(PT.charAt(i));
coords[0][i]=l1/5;
coords[1][i]=l1%5;
}
for (int i=0;i<PT.length();i++)
sb.append(key.charAt(coords[(2*i)/PT.length()][(2*i)%PT.length()]*5+
coords[(2*i+1)/PT.length()][(2*i+1)%PT.length()]));
return sb.toString();
}
// ----------------------------------------------------------------------
@Override
public String decode(String CT)
{
String flat=cs.flattenToCT(CT);
if (period <= 0) return periodDecode(flat);
StringBuilder sb=new StringBuilder();
for (int i=0;i<((flat.length()-1)/period)+1;i++) {
int end=((i+1)*period > flat.length())?flat.length():(i+1)*period;
sb.append(periodDecode(flat.substring(i*period,end)));
}
return sb.toString();
}
// ----------------------------------------------------------------------
private String periodDecode(String CT)
{
int [][] coords=new int[2][CT.length()];
StringBuilder sb=new StringBuilder();
for (int i=0;i<CT.length();i++) {
int l1=key.indexOf(CT.charAt(i));
coords[(2*i)/CT.length()][(2*i)%CT.length()]=l1/5;
coords[(2*i+1)/CT.length()][(2*i+1)%CT.length()]=l1%5;
}
for (int i=0;i<CT.length();i++)
sb.append(key.charAt(coords[0][i]*5+coords[1][i]));
return sb.toString();
}
// ----------------------------------------------------------
public static void main(String [] args) {
Bifid bifid=new Bifid(new Codespace(Codespace.StockAlphabet.MERGED_IJ),"BGWKZQPNDSIOAXEFCLUMTHYVR");
String target="UAEOLWRINS";
String PT="FLEEATONCE";
if (bifid.multiTest() && bifid.knownTest(PT,target)) System.out.println("PASS");
else System.out.println("***** FAIL *******");
}
}