Playfair-Cipher-Encryption.java

import java.util.Scanner;

public class MyProgram{
	
	static void encrypt(String pt, String key) {
		char[] pt_arr=pt.toCharArray();
		char[] key_arr=key.toCharArray();
		char[] alpha={'A','B','C','D','E','F','G','H','I','K','L','M',
		'N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
		char[][] table=new char[5][5];
		char[] encpt_arr = new char[100];
		int encpt_arr_ctr=0;
		int ctr=-1;
		
		for(int i=0;i<key_arr.length;i++)
			for(int j=0;j<25;j++)
				if(key_arr[i]==alpha[j])
				{
					ctr++;
					int round = ctr/5;
					table[round][ctr%5]=alpha[j];
					alpha[j]='0';
					break;
				}
		for(int i=0;i<alpha.length;i++)
		{
			if(alpha[i]!='0')
			{
				ctr++;
				int round = ctr/5;
				table[round][ctr%5]=alpha[i];
			}
		}
		
		
		char[] any=new char[100];
		int c=0;
		for(int i=0;i<pt_arr.length;i++)
		{
			if(i==0 && pt_arr[i]!=pt_arr[i+1] && i+1<pt_arr.length)
			{
				any[c++]=pt_arr[i];
				continue;
			}
			if(i==1 && pt_arr[i]!=pt_arr[i+1] && i+1<pt_arr.length)
			{
				any[c++]=pt_arr[i];
				continue;
			}
			
			
			
			if(i==pt_arr.length-2 && i%2==0 && pt_arr[i]!=pt_arr[i-1]
			&& pt_arr[i]!=pt_arr[i+1])
			{
				any[c++]=pt_arr[i];
				continue;
			}
			if(i==pt_arr.length-2 && i%2==0 && pt_arr[i]!=pt_arr[i-1]
			&& pt_arr[i]==pt_arr[i+1])
			{
				any[c++]=pt_arr[i];
				any[c++]='X';
				continue;
			}
			if(i==pt_arr.length-2 && i%2==0 && pt_arr[i]==pt_arr[i-1]
			&& pt_arr[i]!=pt_arr[i+1])
			{
				any[c++]=pt_arr[i];
				continue;
			}
			if(i==pt_arr.length-2 && i%2==0 && pt_arr[i]==pt_arr[i-1]
			&& pt_arr[i]==pt_arr[i+1])
			{
				any[c++]=pt_arr[i];
				any[c++]='X';
				continue;
			}
			if(i==pt_arr.length-2 && i%2!=0 && pt_arr[i]!=pt_arr[i-1]
			&& pt_arr[i]!=pt_arr[i+1])
			{
				any[c++]=pt_arr[i];
				continue;
			}
			if(i==pt_arr.length-2 && i%2!=0 && pt_arr[i]!=pt_arr[i-1]
			&& pt_arr[i]==pt_arr[i+1])
			{
				any[c++]=pt_arr[i];
				any[c++]='X';
				continue;
			}
			if(i==pt_arr.length-2 && i%2!=0 && pt_arr[i]==pt_arr[i-1]
			&& pt_arr[i]!=pt_arr[i+1])
			{
				any[c++]=pt_arr[i];
				continue;
			}
			if(i==pt_arr.length-2 && i%2!=0 && pt_arr[i]==pt_arr[i-1]
			&& pt_arr[i]==pt_arr[i+1])
			{
				any[c++]=pt_arr[i];
				any[c++]='X';
				continue;
			}
			
			
			if(i==pt_arr.length-1 && i%2==0 && pt_arr[i]!=pt_arr[i-1])
			{
				any[c++]=pt_arr[i];
				continue;
			}
			if(i==pt_arr.length-1 && i%2==0 && pt_arr[i]==pt_arr[i-1])
			{
				any[c++]=pt_arr[i];
				any[c++]='X';
				continue;
			}
			if(i==pt_arr.length-1 && i%2!=0 && pt_arr[i]!=pt_arr[i-1])
			{
				any[c++]=pt_arr[i];
				continue;
			}
			if(i==pt_arr.length-1 && i%2!=0 && pt_arr[i]==pt_arr[i-1])
			{
				any[c++]=pt_arr[i];
				any[c++]='X';
				continue;
			}
			
			
			if(i%2==0 && pt_arr[i]!=pt_arr[i-1] && pt_arr[i]==pt_arr[i+1])
			{
				any[c++]=pt_arr[i];
				any[c++]='X';
				continue;
			}
			if(i%2==0 && pt_arr[i]!=pt_arr[i-1] && pt_arr[i]!=pt_arr[i+1])
			{
				any[c++]=pt_arr[i];
				continue;
			}
			if(i%2==0 && pt_arr[i]==pt_arr[i-1] && pt_arr[i]!=pt_arr[i+1])
			{
				any[c++]=pt_arr[i];
				continue;
			}
			if(i%2==0 && pt_arr[i]==pt_arr[i-1] && pt_arr[i]==pt_arr[i+1])
			{
				any[c++]=pt_arr[i];
				any[c++]='X';
				continue;
			}
			
			
			if(i%2!=0 && pt_arr[i]!=pt_arr[i-1] && pt_arr[i]==pt_arr[i+1])
			{
				any[c++]=pt_arr[i];
				any[c++]='X';
				continue;
			}
			if(i%2!=0 && pt_arr[i]!=pt_arr[i-1] && pt_arr[i]!=pt_arr[i+1])
			{
				any[c++]=pt_arr[i];
				continue;
			}
			if(i%2!=0 && pt_arr[i]==pt_arr[i-1] && pt_arr[i]!=pt_arr[i+1])
			{
				any[c++]=pt_arr[i];
				continue;
			}
			if(i%2!=0 && pt_arr[i]==pt_arr[i-1] && pt_arr[i]==pt_arr[i+1])
			{
				any[c++]=pt_arr[i];
				any[c++]='X';
				continue;
			}
		}
		if(c%2!=0)
			any[c++]='X';
		
		System.out.print("\nThe Intermediate Text is: ");
		for(int i=0;i<c;i++)
			System.out.print(any[i]);
		System.out.println();
		
		for(int i=0;i<c;i=i+2)
		{
			if(any[i]=='J')
				any[i]='I';
			if(any[i+1]=='J')
				any[i+1]='I';
			int row1=0,row2=0,col1=0,col2=0;
			for(int j=0;j<5;j++)
			{
				for(int k=0;k<5;k++)
				{
					if(any[i]==table[j][k])
					{
						row1=j;
						col1=k;
						break;
					}
				}
			}
			for(int j=0;j<5;j++)
			{
				for(int k=0;k<5;k++)
				{
					if(any[i+1]==table[j][k])
					{
						row2=j;
						col2=k;
						break;
					}
				}
			}
			if(row1==row2)
			{
				col1=(col1+1)%5;
				col2=(col2+1)%5;
				encpt_arr[encpt_arr_ctr++]=table[row1][col1];
				encpt_arr[encpt_arr_ctr++]=table[row2][col2];
			}
			else if(col1==col2)
			{
				row1=(row1+1)%5;
				row2=(row2+1)%5;
				encpt_arr[encpt_arr_ctr++]=table[row1][col1];
				encpt_arr[encpt_arr_ctr++]=table[row2][col2];
			}
			else if(row1!=row2 && col1!=col2)
			{
				int row=0,col=0;
				row=row1;
				col=col2;
				encpt_arr[encpt_arr_ctr++]=table[row][col];
				row=row2;
				col=col1;
				encpt_arr[encpt_arr_ctr++]=table[row][col];
			}
			else
			{
				
			}
		}

		System.out.println("\nThe Reference Table is: ");
		for(int i=0;i<5;i++)
		{
			for(int j=0;j<5;j++)
				System.out.print(table[i][j]+" ");
			System.out.print("\n");
		}
		
		System.out.print("\nThe Encrypted text is: ");
		for(int i=0;i<encpt_arr_ctr;i++)
			System.out.print(encpt_arr[i]);
	}
	
	public static void main(String[] args) {
		String pt, key;
		System.out.print("Enter plaintext: ");
		Scanner scanner = new Scanner(System.in);
		pt=scanner.nextLine();
		System.out.print("Enter key: ");
		key=scanner.nextLine();
		scanner.close();
		
		encrypt(pt,key);
		
	}
}