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Monoalphabetic.java
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Monoalphabetic.java
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import java.util.Date;
public class Monoalphabetic extends ClassicalCipher
{
// Specifically monoalphabetic ciphers - can have generic encode and decode
/*
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 int[] key; // The encryption mappings
// ----------------------------------------------------------------------
Monoalphabetic() { super(); key=new int[cs.PTspace.length()];} // Key needs setting later
// ----------------------------------------------------------------------
Monoalphabetic(Codespace cs)
{
super(cs);
key=new int[cs.PTspace.length()]; // Key needs setting later
}
// ----------------------------------------------------------------------
Monoalphabetic(Codespace cs,String skey)
{
super(cs);
if (skey.length()!=cs.PTspace.length()) throw new IllegalArgumentException(
"Key does not cover all of PT space");
key=orderit(skey);
}
// ----------------------------------------------------------------------
Monoalphabetic(Monoalphabetic from)
{
super(from.cs);
key=new int[cs.PTspace.length()];
assignKey(from.key);
}
// --------------------------------------------------------------
@Override
public Monoalphabetic copyInstance(ClassicalCipher c) // Copy factory method
{ return new Monoalphabetic((Monoalphabetic)c); }
// --------------------------------------------------------------
protected void assignKey(int [] keytobe)
{
for (int i=0;i<cs.PTspace.length();i++)
key[i]=keytobe[i];
return;
}
// --------------------------------------------------------------
public boolean equals(Monoalphabetic ma)
{
if (!cs.PTspace.equals(ma.cs.PTspace)) return false;
if (!cs.PTmap.equals(ma.cs.PTmap)) return false;
for (int i=0;i<key.length;i++)
if (key[i]!=ma.key[i]) return false;
return true;
}
// --------------------------------------------------------------
public String toString()
{ return (this.getClass().getName()+" Cipher : Key "+showKey()+
super.toString());}
// --------------------------------------------------------------
public String showKey() { return encode(cs.PTspace); }
// --------------------------------------------------------------
public void randomiseKey() // Sets a fully random key
{
key=new int[cs.PTspace.length()];
boolean [] used=new boolean[key.length];
for (int i=0;i<key.length;i++) {
key[i]=rand.nextInt(key.length);
while (used[key[i]]) key[i]=rand.nextInt(key.length);
used[key[i]]=true;
}
return;
}
// --------------------------------------------------------------
public void randomiseMirrorKey() // Forces a mirrored key i.e. A<->B etc
// If odd number of chars, has one instance of a <-> a
{
int same;
key=new int[cs.PTspace.length()];
boolean [] used=new boolean[key.length];
if ((key.length % 2)==1) {
same=rand.nextInt(key.length);
used[same]=true;
key[same]=same;
}
int nkeys=key.length/2; // designed to round and lose odd
int index=rand.nextInt(key.length);
for (int i=0;i<nkeys;i++) {
while (used[index]) index=rand.nextInt(key.length);
used[index]=true;
key[index]=rand.nextInt(key.length);
while (used[key[index]]) key[index]=rand.nextInt(key.length);
used[key[index]]=true;
key[key[index]]=index; // Recripocal
index=rand.nextInt(key.length);
}
return;
}
// ----------------------------------------------------------------------
@Override
public String encode(String PT)
{
String flat=cs.flattenToPT(PT);
StringBuilder sb=new StringBuilder();
for (int i=0;i<flat.length();i++)
sb.append(cs.CTspace.charAt(key[cs.PTspace.indexOf(flat.charAt(i))]));
return sb.toString();
}
// ----------------------------------------------------------------------
@Override
public String decode(String CT)
{
String flat=cs.flattenToCT(CT);
StringBuilder sb=new StringBuilder();
int[] invkey=invert(key); // Only used here, so set before use
for (int i=0;i<flat.length();i++)
sb.append(cs.PTspace.charAt(invkey[cs.CTspace.indexOf(flat.charAt(i))]));
return sb.toString();
}
// ----------------------------------------------------------------------
public static void main(String [] args) {
Monoalphabetic mo=new Monoalphabetic(new Codespace(Codespace.StockAlphabet.CAPITALS));
}
}