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ClassicalCipher.java
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ClassicalCipher.java
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import java.util.List;
import java.util.ArrayList;
public class ClassicalCipher extends Encoding
{
// Generic Cipher utilities and base class for other ciphers
/*
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/>. */
// ----------------------------------------------------------------------
ClassicalCipher() { super(); }
ClassicalCipher(Codespace cs) { super(cs); }
// ----------------------------------------------------------------------
public ClassicalCipher copyInstance(ClassicalCipher c) // Copy factory method
{ return new ClassicalCipher(c.cs); }
// ----------------------------------------------------------------------
public String encode(String text) { return text; } // Functions as null cipher
public String decode(String text) { return text; } // Ditto
// ----------------------------------------------------------------------
public String seriateOn(String text,int rank)
{
StringBuilder sb=new StringBuilder();
int therank=rank; // start here
int x0=0; // ditto
while (x0<text.length()) {
int numberLeft=text.length()-x0;
if (numberLeft < therank*2) therank=(numberLeft+1)/2;
for (int r=0;r<therank;r++) {
sb.append(text.charAt(x0+r));
if (x0+r+therank < text.length())
sb.append(text.charAt(x0+r+therank));
}
x0+=(2*therank);
}
return sb.toString();
}
// ----------------------------------------------------------------------
public String seriateOff(String text,int rank)
{
StringBuilder sb=new StringBuilder();
int therank=rank; // start here
int x0=0; // ditto
while (x0<text.length()) {
int numberLeft=text.length()-x0;
if (numberLeft < therank*2) therank=(numberLeft+1)/2;
for (int r=0;r<therank*2;r+=2)
sb.append(text.charAt(x0+r));
for (int r=1;r<therank*2;r+=2)
if ((x0+r) < text.length())
sb.append(text.charAt(x0+r));
x0+=(2*therank);
}
return sb.toString();
}
// ----------------------------------------------------------------------
protected String regularise(String text,int rank,String nulls) {
// Pads a string to make a columnar cipher regular
if ((text.length()%rank)==0) return text;
StringBuilder reg=new StringBuilder(rank*(1+text.length()/rank));
reg.append(text);
for (int i=0;i<(rank-(text.length()%rank));i++)
reg.append(nulls.charAt(rand.nextInt(nulls.length())));
return (reg.toString());
}
// ----------------------------------------------------------------------
protected String pad(String word) {
// Pads a string to alphabet chars with unique letters in alphabetic order
StringBuilder pad=new StringBuilder();
for (int i=0;i<cs.PTspace.length();i++)
if (!word.contains(Character.toString(cs.PTspace.charAt(i))))
pad.append(Character.toString(cs.PTspace.charAt(i)));
return (pad.insert(0,word).toString());
}
// ----------------------------------------------------------------------
protected String dap(String word) {
// Pads a string to alphabet chars with unique letters in reverse
// alphabetic order (i.e. reverse of pad)
StringBuilder pad=new StringBuilder();
for (int i=0;i<cs.PTspace.length();i++)
if (!word.contains(Character.toString(cs.PTspace.charAt(cs.PTspace.length()-1-i))))
pad.append(Character.toString(cs.PTspace.charAt(cs.PTspace.length()-1-i)));
return (pad.insert(0,word).toString());
}// ----------------------------------------------------------------------
protected String padnull(String word) {
// Pads a string to alphabet chars with unique letters in alphabetic order
// and nulls in place of repeated letters
StringBuilder pad=new StringBuilder();
for (int i=0;i<cs.PTspace.length();i++)
if (!word.contains(Character.toString(cs.PTspace.charAt(i))))
pad.append(Character.toString(cs.PTspace.charAt(i)));
else
pad.append("_");
return (pad.insert(0,word).toString());
}
// ----------------------------------------------------------------------
public static String map(String text,int [] transpose)
{
// Example input : text ABCDE and order 42013, produces ECABD
// Inverting 42013 gives 23140
// Transposition cipher generic. When provided by the array that dictates
// that text2 1stletter in nth position to text2 letter m, construct text2
// Forces exact length match, otherwise same as permute.
if (text.length() != transpose.length) System.out.println("Length Mismatch");
return permute(text,transpose);
}
// ----------------------------------------------------------------------
public static String permute(String text,int [] transpose)
{
// Permutes the text string using the transpose array, repeats if
// text is longer than transpose.
// TODO : If not integer multiples, currently potentially shortens string
// because cannot map from beyond end
// Not obvious how to work if not multiple.
StringBuilder result=new StringBuilder(text.length());
for (int index=0;index<text.length();index++) {
int ti=transpose.length*(index/transpose.length)+
transpose[index%transpose.length];
if (ti<text.length())
result.append(Character.toString(text.charAt(ti)));
}
return result.toString();
}
// ----------------------------------------------------------------------
public static int[] getMap(int length,int [] order)
{
// Given a text of length 'length', return the mapping between original chars
// and new chars (new = transpose[old]) constructed by placing text in as many
// columns as are in the order array, and reading off from top to bottom of the
// columns in the order specified by order[].
// Constraints : order contains 0 to n-1 in some order. No repeats/omissions
// Assumes a regular array.
int [] transpose=new int[length];
int serial=0;
int ncol=order.length;
int nrow=(int)((length-1)/ncol)+1;
for (int col=0;col<ncol;col++)
for (int row=0;row<nrow;row++) {
//??? int index=(nrow-1-row)*ncol+order[col];
int index=row*ncol+order[col];
if (index < length)
transpose[index]=serial++;
}
return transpose;
}
// ----------------------------------------------------------------------
public static String invertByCols(String text,int [] order)
{ // Keyed columnar transposition
int [] transpose=getMap(text.length(),order);
return map(text,transpose); // map is the 'inverted' version anyway
}
// ----------------------------------------------------------------------
public static String byCols(String text,int [] order)
{ // Inverted Keyed columnar transposition
int [] transpose=getMap(text.length(),order);
return map(text,invert(transpose));
}
// ----------------------------------------------------------------------
public static int[] invert(int[] list)
{ // Inverts a mapping.
int [] inv=new int[list.length];
for (int i=0;i<list.length;i++)
inv[list[i]]=i;
return (inv);
}
// ----------------------------------------------------------------------
public int[] orderit(String word)
{ // Returns array keyed by order of letters with duplicates leading to
// same numbers. i.e. ACB returns [0,2,1]; ACCB is [0,2,2,1]
// May sometimes be helpful to call with words with unique letters (use unique())
// see also oneorderit()
int [] result=new int[word.length()];
int place=0;
for (int i=0;i<cs.PTspace.length();i++)
if (word.contains(Character.toString(cs.PTspace.charAt(i)))) {
for (int j=0;j<word.length();j++)
if (word.charAt(j)==cs.PTspace.charAt(i))
result[j]=place;
place++;
}
return result;
}
// ----------------------------------------------------------------------
public int[] oneorderit(String word)
{ // Returns array keyed by order of letters, with duplicates leading to
// consecutive numbers, i.e. all numbers are unique. e.g. ACB returns [0,2,1];
// ACCB is [0,2,3,1]
// May sometimes be helpful to use with words with unique letters. See also orderit()
int [] result=new int[word.length()];
int place=0;
for (int i=0;i<cs.PTspace.length();i++)
if (word.contains(Character.toString(cs.PTspace.charAt(i)))) {
for (int j=0;j<word.length();j++)
if (word.charAt(j)==cs.PTspace.charAt(i)) {
result[j]=place++;
}
}
return result;
}
// ----------------------------------------------------------------------
public static String uniquenull(String word) {
// Returns the unique letters of word in original order, with nulls ("_")
// in the repeat positions
StringBuilder unique=new StringBuilder(Character.toString(word.charAt(0)));
for (int i=1;i<word.length();i++)
if (unique.indexOf(word.substring(i,i+1))==(-1))
unique.append(Character.toString(word.charAt(i)));
else
unique.append("_");
return unique.toString();
}
// ----------------------------------------------------------------------
public String getCanonical(String word) {
// Returns a canonical monoalphabetic representation by replacing letters
// of word with ordered letters of PTspace. e.g. TEST = ABCA
StringBuilder canonical=new StringBuilder(word.length());
int index=0;
for (int i=0;i<word.length();i++) {
int place=word.substring(0,i).indexOf(word.substring(i,i+1));
if (place==(-1))
canonical.append(Character.toString(cs.PTspace.charAt(index++)));
else
canonical.append(canonical.substring(place,place+1));
}
return canonical.toString();
}
// ----------------------------------------------------------------------
public int [] getCanonicalInt(String word) {
// Returns a canonical monoalphabetic representation by replacing letters
// of word with ordered numbers e.g. TEST = [0,1,2,0]
int [] canonical=new int[word.length()];
int index=0;
for (int i=0;i<word.length();i++) {
int place=word.substring(0,i).indexOf(word.substring(i,i+1));
if (place==(-1))
canonical[i]=index++;
else
canonical[i]=canonical[place];
}
return canonical;
}
}