Skip to content

Commit 2128c7a

Browse files
joaomagfreitasjoaomagfreitas
committed
Columnar Transposition Cipher with example usage
1 parent e44016c commit 2128c7a

File tree

1 file changed

+169
-0
lines changed

1 file changed

+169
-0
lines changed

‎ciphers/ColumnarTranspositionCipher.java

Lines changed: 169 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,169 @@
1+
/**
2+
* Columnar Transposition Cipher Encryption and Decryption.
3+
* @author <a href="https://github.com/freitzzz">freitzzz</a>
4+
*/
5+
public class ColumnarTranspositionCipher {
6+
private static String keyword;
7+
private static Object[][] table;
8+
private static String abecedarium;
9+
public static final String ABECEDARIUM="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789,.;:-@";
10+
private static final String ENCRYPTION_FIELD="≈";
11+
private static final char ENCRYPTION_FIELD_CHAR='≈';
12+
/**
13+
* Encrypts a certain String with the Columnar Transposition Cipher Rule
14+
* @param word Word being encrypted
15+
* @param keyword String with keyword being used
16+
* @return a String with the word encrypted by the Columnar Transposition Cipher Rule
17+
*/
18+
public static String encrpyter(String word,String keyword){
19+
ColumnarTranspositionCipher.keyword=keyword;
20+
abecedariumBuilder(500);
21+
table=tableBuilder(word);
22+
Object[][] sortedTable=sortTable(table);
23+
String wordEncrypted="";
24+
for(int i=0;i<sortedTable[0].length;i++){
25+
for(int j=1;j<sortedTable.length;j++){
26+
wordEncrypted+=sortedTable[j][i];
27+
}
28+
}
29+
return wordEncrypted;
30+
}
31+
32+
/**
33+
* Encrypts a certain String with the Columnar Transposition Cipher Rule
34+
* @param word Word being encrypted
35+
* @param keyword String with keyword being used
36+
* @param abecedarium String with the abecedarium being used. null for default one
37+
* @return a String with the word encrypted by the Columnar Transposition Cipher Rule
38+
*/
39+
public static String encrpyter(String word,String keyword,String abecedarium){
40+
ColumnarTranspositionCipher.keyword=keyword;
41+
if(abecedarium!=null){
42+
ColumnarTranspositionCipher.abecedarium=abecedarium;
43+
}else{
44+
ColumnarTranspositionCipher.abecedarium=ABECEDARIUM;
45+
}
46+
table=tableBuilder(word);
47+
Object[][] sortedTable=sortTable(table);
48+
String wordEncrypted="";
49+
for(int i=0;i<sortedTable[0].length;i++){
50+
for(int j=1;j<sortedTable.length;j++){
51+
wordEncrypted+=sortedTable[j][i];
52+
}
53+
}
54+
return wordEncrypted;
55+
}
56+
/**
57+
* Decryps a certain encrypted String with the Columnar Transposition Cipher Rule
58+
* @return a String decrypted with the word ecrypted by the Columnar Transpositiion Cipher Rule
59+
*/
60+
public static String decrypter(){
61+
String wordDecrypted="";
62+
for(int i=1;i<table.length;i++){
63+
for(int j=0;j<table[i].length;j++){
64+
wordDecrypted+=table[i][j];
65+
}
66+
}
67+
return wordDecrypted.replaceAll(ENCRYPTION_FIELD,"");
68+
}
69+
/**
70+
* Builds a table with the word to be encrpyted in rows by the Columnar Transposition Cipher Rule
71+
* @return An Object[][] with the word to be encrypted filled in rows and columns
72+
*/
73+
private static Object[][] tableBuilder(String word){
74+
Object[][] table=new Object[rows(word)+1][keyword.length()];
75+
char[] wordInChards=word.toCharArray();
76+
//Fils in the respective numbers
77+
table[0]=findElements();
78+
int charElement=0;
79+
for(int i=1;i<table.length;i++){
80+
for(int j=0;j<table[i].length;j++){
81+
if(charElement<wordInChards.length){
82+
table[i][j]=(char)wordInChards[charElement];
83+
charElement++;
84+
}else{
85+
table[i][j]=ENCRYPTION_FIELD_CHAR;
86+
}
87+
}
88+
}
89+
return table;
90+
}
91+
/**
92+
* Determines the number of rows the table should have regarding the Columnar Transposition Cipher Rule
93+
* @return an int with the number of rows that the table should have in order to respect the Columnar Transposition Cipher Rule.
94+
*/
95+
private static int rows(String word){
96+
if((double)word.length()/keyword.length()>word.length()/keyword.length()){
97+
return (word.length()/keyword.length())+1;
98+
}else{
99+
return word.length()/keyword.length();
100+
}
101+
}
102+
private static Object[] findElements(){
103+
Object[] charValues=new Object[keyword.length()];
104+
for(int i=0;i<charValues.length;i++){
105+
for(int j=0;j<abecedarium.length();j++){
106+
if(keyword.charAt(i)==abecedarium.charAt(j))charValues[i]=j;
107+
}
108+
}
109+
return charValues;
110+
}
111+
private static Object[][] sortTable(Object[][] table){
112+
Object[][] tableSorted=new Object[table.length][table[0].length];
113+
for(int i=0;i<tableSorted.length;i++){
114+
for(int j=0;j<tableSorted[i].length;j++){
115+
tableSorted[i][j]=table[i][j];
116+
}
117+
}
118+
for(int i=0;i<tableSorted[0].length;i++){
119+
for(int j=i+1;j<tableSorted[0].length;j++){
120+
if((int)tableSorted[0][i]>(int)table[0][j]){
121+
Object[] column=getColumn(tableSorted,tableSorted.length,i);
122+
switchColumns(tableSorted,j,i,column);
123+
}
124+
}
125+
}
126+
return tableSorted;
127+
}
128+
private static Object[] getColumn(Object[][] table,int rows,int column){
129+
Object[] columnArray=new Object[rows];
130+
for(int i=0;i<rows;i++){
131+
columnArray[i]=table[i][column];
132+
}
133+
return columnArray;
134+
}
135+
private static void switchColumns(Object[][] table, int firstColumnIndex,int secondColumnIndex,Object[] columnToSwitch){
136+
for(int i=0;i<table.length;i++){
137+
table[i][secondColumnIndex]=table[i][firstColumnIndex];
138+
table[i][firstColumnIndex]=columnToSwitch[i];
139+
}
140+
}
141+
/**
142+
* Creates an abecedarium with a specified ascii inded
143+
* @param value Number of characters being used based on the ASCII Table
144+
*/
145+
private static void abecedariumBuilder(int value){
146+
abecedarium="";
147+
for(int i=0;i<value;i++){
148+
abecedarium+=(char)i;
149+
}
150+
}
151+
private static void showTable(){
152+
for(int i=0;i<table.length;i++){
153+
for(int j=0;j<table[i].length;j++){
154+
System.out.print(table[i][j]+" ");
155+
}
156+
System.out.println();
157+
}
158+
}
159+
public static void main(String[] args){
160+
String keywordForExample="asd215";
161+
String wordBeingEncrypted="This is a test of the Columnar Transposition Cipher";
162+
System.out.println("### Example of Columnar Transposition Cipher ###\n");
163+
System.out.println("Word being encryped ->>> "+wordBeingEncrypted);
164+
System.out.println("Word encrypted ->>> "+ColumnarTranspositionCipher.encrpyter(wordBeingEncrypted,keywordForExample));
165+
System.out.println("Word decryped ->>> "+ColumnarTranspositionCipher.decrypter());
166+
System.out.println("\n### Encrypted Table ###");
167+
showTable();
168+
}
169+
}

0 commit comments

Comments
 (0)
pFad - Phonifier reborn

Pfad - The Proxy pFad of © 2024 Garber Painting. All rights reserved.

Note: This service is not intended for secure transactions such as banking, social media, email, or purchasing. Use at your own risk. We assume no liability whatsoever for broken pages.


Alternative Proxies:

Alternative Proxy

pFad Proxy

pFad v3 Proxy

pFad v4 Proxy