BadPaddingException: Data must start with zero

[Anita Singh]

Hi,
I have saved the password in database in Encrypted form successfully.But it shows me "javax.crypto.BadPaddingException: Data must start with zero" Exception while Decryption.I m posting here both the Encryption & Decryption code.Please Help Me.

//Code For Encryption
package PracticeApplication1;
import java.util.Date;
import java.util.*;
import java.security.*;
import javax.crypto.*; 
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import java.sql.*;
 
public class RSAPasswordEncryption {
    
    public static void main(String args[])
    {
        String uname="AnitaSingh";
        String password="AnitaSingh";
         try{  
          //Security for password encryption
            Security.addProvider(new BouncyCastleProvider()); 
            KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
            SecureRandom random = SecureRandom.getInstance("SHA1PRNG", "SUN");
            keyGen.initialize(1024, random);
            KeyPair pair = keyGen.generateKeyPair();
            PrivateKey priv = pair.getPrivate();
            PublicKey pub = pair.getPublic();
   
   
            /* Create the cipher */
            Cipher rsaCipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
    
            // Initialize the cipher for encryption
            rsaCipher.init(Cipher.ENCRYPT_MODE, pub);
    
            // Cleartext
            byte[] cleartext = null;
            cleartext = password.getBytes();
            String theString = new String(cleartext); 
            System.out.println("Original String:"+theString);
            
            // Encrypt the cleartext
            byte[] ciphertext = null;
            ciphertext = rsaCipher.doFinal(cleartext);
            System.out.println("the encrypted text is: " + ciphertext.toString()); 
 
            Class.forName("org.gjt.mm.mysql.Driver");
          
            Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/anita","root","root");
            PreparedStatement pstmt=con.prepareStatement("insert into upassword values(?,?)");
            pstmt.setString(1,uname);
            System.out.println(ciphertext);
            pstmt.setString(2,ciphertext.toString());
            pstmt.execute();
            System.out.println("Hello from backing .. 2");
            System.out.println(uname);
             rsaCipher.init(Cipher.DECRYPT_MODE, priv);
         
            }  
       catch(Exception e){System.out.println(e);}
        
    }  
 
  } 

/*Encryption program is working fine*/
************************************************************************

//CODE For Decryption
package PracticeApplication1;
import java.util.Date;
import java.util.*;
import java.security.*;
import javax.crypto.*; 
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import java.sql.*;
import org.bouncycastle.util.encoders.Base64Encoder;
 
public class RSAPasswordDecryption {
    public static void main(String args[])
    {
       
      String uname="AnitaSingh";        
        try {
            System.out.println("Inside Try");
            Class.forName("org.gjt.mm.mysql.Driver");    
            Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/anita","root","root");
            PreparedStatement pstmt=con.prepareStatement("select * from upassword where uname=?");
            pstmt.setString(1,uname);
            ResultSet rs= pstmt.executeQuery();
            System.out.println("After Query Execution");
            while(rs.next())
            {   
                System.out.println("Inside rs.next()");
                System.out.println(rs.getString("password"));
                byte[] password1=rs.getBytes("password");
                System.out.println(password1);
                Security.addProvider(new BouncyCastleProvider()); 
    KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
    SecureRandom random = SecureRandom.getInstance("SHA1PRNG", "SUN");
    keyGen.initialize(1024, random);
    KeyPair pair = keyGen.generateKeyPair();
    PrivateKey priv = pair.getPrivate();
    PublicKey pub = pair.getPublic();
   
    /* Create the cipher */
    Cipher rsaCipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
    
       // Initialize the same cipher for decryption
    rsaCipher.init(Cipher.DECRYPT_MODE, priv);
   
    // Decrypt the ciphertext
    byte[] cleartext1 = rsaCipher.doFinal(password1);
    System.out.println("After dofinal");
    String theString1 = new String(cleartext1); 
    System.out.println("the final cleartext is: " + theString1);
         }
        }
       catch(Exception e){System.out.println(e);
       }
        
    }  
 
}

Please help me
Thanks in Advance

[Rahul Bhattacharjee]

It seems like you are using one set of key pair for encrypting and another for decrypting.

[Anita Singh]

Thanks Rahul
I got it.