SIMPLIFIED DATA ENCRYPTION STANDARD (S-DES) implementation java

SDES.java

import java.awt.datatransfer.StringSelection;
import java.io.DataInputStream;
/*
 * Link For reference: https://www.brainkart.com/article/Simplified-Data-Encryption-Standard-(S-DES)_8343/
 */ // https://www.brainkart.com/article/Simplified-Data-Encryption-Standard-(S-DES)_8343/
public class SDES {

	public int K1,K2;
//Note: below matrics will be provided in lab(PICT)..
	//For performing P10 permutation
	public static final int P10[] = { 3, 5, 2, 7, 4, 10, 1, 9, 8, 6};  
    public static final int P10max = 10;
    //10 to 8 bit permutation
    public static final int P8[] = { 6, 3, 7, 4, 8, 5, 10, 9};
    public static final int P8max = 10;
    public static final int P4[] = { 2, 4, 3, 1};
    public static final int P4max = 4;
    //Performing initial permutaion
    public static final int IP[] = { 2, 6, 3, 1, 4, 8, 5, 7};
    public static final int IPmax = 8;
    //performing final permuttaion(Inverse of initial permutation)
    public static final int IPI[] = { 4, 1, 3, 5, 7, 2, 8, 6};
    public static final int IPImax = 8;
    //expansion/permutation operation:Used in F1 Function
    public static final int EP[] = { 4, 1, 2, 3, 2, 3, 4, 1};
    public static final int EPmax = 4;
    public static final int S0[][] = {{ 1, 0, 3, 2},{ 3, 2, 1, 0},{ 0, 2, 1,
                                                          3},{ 3, 1, 3, 2}};
    public static final int S1[][] = {{ 0, 1, 2, 3},{ 2, 0, 1, 3},{ 3, 0, 1,
                                                          2},{ 2, 1, 0, 3}};
    
    
    /*
     * Generic Function to perform all permutations
     */
    public static int permute(int x, int p[], int pmax) {
    	int y=0;
    	//System.out.println(Integer.toBinaryString(x));
    	/*
    	String binary=Integer.toBinaryString(x);
    	StringBuffer br=new StringBuffer(new String(new char[10]).replace("\0", "0"));
    	*/
    	for(int i=0;i<p.length;i++) {
    	//	br.setCharAt(i, binary.charAt(p[i]-1));
    		y=y<<1;
    		y=y|(x>>(pmax-p[i]))&1;
    	}
    	//System.out.println("Final :"+Integer.toBinaryString(y));
    	return y;
    }
    public static int F( int R, int K)
    {
       int t = permute( R, EP, EPmax) ^ K;
       int t0 = (t >> 4) & 0xF;
       int t1 = t & 0xF;
       t0 = S0[ ((t0 & 0x8) >> 2) | (t0 & 1) ][ (t0 >> 1) & 0x3 ];
       t1 = S1[ ((t1 & 0x8) >> 2) | (t1 & 1) ][ (t1 >> 1) & 0x3 ];
        t = permute( (t0 << 2) | t1, P4, P4max);
      return t;
    
}

public static int fK( int m, int K)
     {
         int L = (m >> 4) & 0xF;
         int R = m & 0xF;
         return ((L ^ F(R,K)) << 4) | R;
     }
    
public static int SW( int x)
{
return ((x & 0xF) << 4) | ((x >> 4) & 0xF);
}
    
    /*
     * Ciphertext = IP-1 (fK2 (SW (fk1 (IP (plaintext))))
     */
     public byte encrypt( int m)
    
     {
      System.out.println("\nEncryption Process Starts........\n\n"); 
       m = permute( m, IP, IPmax);
      System.out.print("\nAfter Initial Permutation(IP) : ");
       printData( m, 8);
       m = fK( m, K1);
       System.out.print("\nbefore Swap : ");
       printData( m, 8);
       m = SW( m);
       System.out.print("\nAfter Swap : ");
       printData( m, 8);
       m = fK( m, K2);
       System.out.print("\nbefore IP inverse : ");
       printData( m, 8);
       m = permute( m, IPI, IPImax);
       return (byte) m;
    
     }
    
    /*
     * Plaintext = IP-1 (fK1 (SW (fk2 (IP (ciphertext)))))
     */
     public byte decrypt( int m)
    
     {
       System.out.println("\nDecryption Process Starts........\n\n");
       printData( m, 8);
       m = permute( m, IP, IPmax);
       System.out.print("\nAfter Permutation : ");
       printData( m, 8);
       m = fK( m, K2);
       System.out.print("\nbefore Swap : ");
       printData( m, 8);
       m = SW( m);
       System.out.print("\nAfter Swap : ");
       printData( m, 8);
       m = fK( m, K1);
       System.out.print("\nBefore Extraction Permutation : ");
       printData( m, 4);
       m = permute( m, IPI, IPImax);
       System.out.print("\nAfter Extraction Permutation : ");
       printData( m, 8);
       return (byte) m;
    
     }
    
     public static void printData( int x, int n)
      {
        int mask = 1 << (n-1);
        while( mask > 0)
        {
        System.out.print( ((x & mask) == 0) ? '0' : '1');
        mask >>= 1;
        }
     }
    
    
    /*
     * 
     * K1 = P8 (Shift_1 (P10 (Key)))
	   K2 = P8 (Shift_2 (shift_1 (P10 (Key))))
     */
     public SDES( int K) //COnstructor generates key k1 & k2 used for encyption
   {
       K = permute( K, P10, P10max);
       int t1 = (K >> 5) & 0x1F;
       int t2 = K & 0x1F;
       t1 = ((t1 & 0xF) << 1) | ((t1 & 0x10) >> 4);
       t2 = ((t2 & 0xF) << 1) | ((t2 & 0x10) >> 4);
       K1 = permute( (t1 << 5)| t2, P8, P8max);
       t1 = ((t1 & 0x7) << 2) | ((t1 & 0x18) >> 3);
       t2 = ((t2 & 0x7) << 2) | ((t2 & 0x18) >> 3);
       K2 = permute( (t1 << 5)| t2, P8, P8max);
    
     }
    
   

	
     @SuppressWarnings("deprecation")
	public static void main( String args[]) throws Exception
     {
      DataInputStream inp=new DataInputStream(System.in);
      System.out.println("Enter the 10 Bit Key :"); //1011011010
       int K = Integer.parseInt(inp.readLine(),2);
       SDES A = new SDES( K);
       System.out.println("Enter the 8 Bit message To be Encrypt  : ");
       int m = Integer.parseInt(inp.readLine(),2); //10110110
       System.out.print("\nKey K1: ");
       SDES.printData( A.K1, 8);
       System.out.print("\nKey K2: ");
       SDES.printData( A.K2, 8);
       m = A.encrypt( m);
       System.out.print("\nEncrypted Message: ");
       SDES.printData( m, 8);
       m = A.decrypt( m);
       System.out.print("\nDecrypted Message: ");
       SDES.printData( m, 8);
    
     }
	
}

SDES_output.txt

/*
 * 
Enter the 10 Bit Key :
1011011010
Enter the 8 Bit message To be Encrypt  : 
10110110

Key K1: 11110101
Key K2: 01100011
Encryption Process Starts........



After Permutation : 01111001
before Swap : 00001001
After Swap : 10010000
before IP inverse : 10000000
Encrypted Message: 01000000
Decryption Process Starts........


01000000
After Permutation : 10000000
before Swap : 10010000
After Swap : 00001001
Before Extraction Permutation : 1001
After Extraction Permutation : 10110110
Decrypted Message: 10110110
 */