This is a java program to implement playfair cipher algorithm. The Playfair cipher or Playfair square is a manual symmetric encryption technique and was the first literal digraph substitution cipher.
Here is the source code of the Java Program to Decode a Message Encoded Using Playfair Cipher. The Java program is successfully compiled and run on a Windows system. The program output is also shown below.
package com.maixuanviet.setandstring; import java.util.Scanner; public class PlayfairCipherDecryption { private String KeyWord = new String(); private String Key = new String(); private char matrix_arr[][] = new char[5][5]; public void setKey(String k) { String K_adjust = new String(); boolean flag = false; K_adjust = K_adjust + k.charAt(0); for (int i = 1; i < k.length(); i++) { for (int j = 0; j < K_adjust.length(); j++) { if (k.charAt(i) == K_adjust.charAt(j)) { flag = true; } } if (flag == false) K_adjust = K_adjust + k.charAt(i); flag = false; } KeyWord = K_adjust; } public void KeyGen() { boolean flag = true; char current; Key = KeyWord; for (int i = 0; i < 26; i++) { current = (char) (i + 97); if (current == 'j') continue; for (int j = 0; j < KeyWord.length(); j++) { if (current == KeyWord.charAt(j)) { flag = false; break; } } if (flag) Key = Key + current; flag = true; } System.out.println(Key); matrix(); } private void matrix() { int counter = 0; for (int i = 0; i < 5; i++) { for (int j = 0; j < 5; j++) { matrix_arr[i][j] = Key.charAt(counter); System.out.print(matrix_arr[i][j] + " "); counter++; } System.out.println(); } } private String format(String old_text) { int i = 0; int len = 0; String text = new String(); len = old_text.length(); for (int tmp = 0; tmp < len; tmp++) { if (old_text.charAt(tmp) == 'j') { text = text + 'i'; } else text = text + old_text.charAt(tmp); } len = text.length(); for (i = 0; i < len; i = i + 2) { if (text.charAt(i + 1) == text.charAt(i)) { text = text.substring(0, i + 1) + 'x' + text.substring(i + 1); } } return text; } private String[] Divid2Pairs(String new_string) { String Original = format(new_string); int size = Original.length(); if (size % 2 != 0) { size++; Original = Original + 'x'; } String x[] = new String[size / 2]; int counter = 0; for (int i = 0; i < size / 2; i++) { x[i] = Original.substring(counter, counter + 2); counter = counter + 2; } return x; } public int[] GetDiminsions(char letter) { int[] key = new int[2]; if (letter == 'j') letter = 'i'; for (int i = 0; i < 5; i++) { for (int j = 0; j < 5; j++) { if (matrix_arr[i][j] == letter) { key[0] = i; key[1] = j; break; } } } return key; } public String encryptMessage(String Source) { String src_arr[] = Divid2Pairs(Source); String Code = new String(); char one; char two; int part1[] = new int[2]; int part2[] = new int[2]; for (int i = 0; i < src_arr.length; i++) { one = src_arr[i].charAt(0); two = src_arr[i].charAt(1); part1 = GetDiminsions(one); part2 = GetDiminsions(two); if (part1[0] == part2[0]) { if (part1[1] < 4) part1[1]++; else part1[1] = 0; if (part2[1] < 4) part2[1]++; else part2[1] = 0; } else if (part1[1] == part2[1]) { if (part1[0] < 4) part1[0]++; else part1[0] = 0; if (part2[0] < 4) part2[0]++; else part2[0] = 0; } else { int temp = part1[1]; part1[1] = part2[1]; part2[1] = temp; } Code = Code + matrix_arr[part1[0]][part1[1]] + matrix_arr[part2[0]][part2[1]]; } return Code; } public String decryptMessage(String Code) { String Original = new String(); String src_arr[] = Divid2Pairs(Code); char one; char two; int part1[] = new int[2]; int part2[] = new int[2]; for (int i = 0; i < src_arr.length; i++) { one = src_arr[i].charAt(0); two = src_arr[i].charAt(1); part1 = GetDiminsions(one); part2 = GetDiminsions(two); if (part1[0] == part2[0]) { if (part1[1] > 0) part1[1]--; else part1[1] = 4; if (part2[1] > 0) part2[1]--; else part2[1] = 4; } else if (part1[1] == part2[1]) { if (part1[0] > 0) part1[0]--; else part1[0] = 4; if (part2[0] > 0) part2[0]--; else part2[0] = 4; } else { int temp = part1[1]; part1[1] = part2[1]; part2[1] = temp; } Original = Original + matrix_arr[part1[0]][part1[1]] + matrix_arr[part2[0]][part2[1]]; } return Original; } public static void main(String[] args) { PlayfairCipherDecryption x = new PlayfairCipherDecryption(); Scanner sc = new Scanner(System.in); System.out.println("Enter a keyword:"); String keyword = sc.next(); x.setKey(keyword); x.KeyGen(); System.out .println("Enter word to encrypt: (Make sure length of message is even)"); String key_input = sc.next(); if (key_input.length() % 2 == 0) { System.out.println("Encryption: " + x.encryptMessage(key_input)); System.out.println("Decryption: " + x.decryptMessage(x.encryptMessage(key_input))); } else { System.out.println("Message length should be even"); } sc.close(); } }
Output:
$ javac PlayfairCipherDecryption.java $ java PlayfairCipherDecryption Enter a keyword: sanfoundry sanfoudrybceghiklmpqtvwxz s a n f o u d r y b c e g h i k l m p q t v w x z Enter word to encrypt: (Make sure length of message is even) learning Encryption: vlndogrm Decryption: learning
Related posts:
Spring Boot - File Handling
Automatic Property Expansion with Spring Boot
Removing Elements from Java Collections
Java Program to implement Sparse Vector
How to Change the Default Port in Spring Boot
Java Program to Check whether Directed Graph is Connected using DFS
Jackson Exceptions – Problems and Solutions
Spring MVC and the @ModelAttribute Annotation
Spring Cloud AWS – S3
Java Program to Implement Sieve Of Eratosthenes
Java – Generate Random String
Spring Boot - Build Systems
Introduction to Spliterator in Java
Function trong Java 8
Returning Custom Status Codes from Spring Controllers
Guava CharMatcher
Java Program to Implement Binary Search Tree
Java Program to Implement LinkedTransferQueue API
The Order of Tests in JUnit
Java Program to Generate Random Numbers Using Middle Square Method
Java Program to Check Whether a Weak Link i.e. Articulation Vertex Exists in a Graph
Java Program to Implement CopyOnWriteArrayList API
An Introduction to ThreadLocal in Java
Removing all duplicates from a List in Java
Java Program to Implement Shell Sort
Removing all Nulls from a List in Java
Spring Boot - Code Structure
Configure a Spring Boot Web Application
Java Program to Check if a Point d lies Inside or Outside a Circle Defined by Points a, b, c in a Pl...
The Difference Between Collection.stream().forEach() and Collection.forEach()
Getting Started with GraphQL and Spring Boot
Java Program to Implement Stack using Two Queues