Decrypt cypher text 

 http://www.bouncycastle.org/.../bcprov-ext-jdk15on-151.jar

bcprov-ext-jdk15on-151-jar

Add this jar to library folder.

Start a java application.

Get a jframe and name it as main.java,

Add three text fields

type-To type the value

encypt-To display encyted code.

decrypt-To display decrypted cod.

public class Main extends javax.swing.JFrame {
    /**
     * encryption and decryption
     */
 
    byte[] input;
    byte[] keyBytes = "12345678".getBytes(); // our own key
    byte[] ivBytes = "input123".getBytes();
 
    SecretKeySpec key = new SecretKeySpec(keyBytes, "DES");
    IvParameterSpec ivSpec = new IvParameterSpec(ivBytes);
    Cipher cipher;
    byte[] chiperText;
    int ctLenght;
    /**
     * Creates new form Main
     */
    public Main() {
        initComponents();
    }

--------------------------------Encryption-----------------------------------------------------------------------------

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         

        try {

            Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider()); //type of security

            input = type.getText().getBytes();

            SecretKeySpec key = new SecretKeySpec(keyBytes, "DES");

            IvParameterSpec ivSpec = new IvParameterSpec(ivBytes);

            

            cipher = Cipher.getInstance("DES/CTR/NoPadding", "BC"); //CTR of encryption

            cipher.init(Cipher.ENCRYPT_MODE, key, ivSpec);

            chiperText = new byte[cipher.getOutputSize(input.length)];

            ctLenght = cipher.update(input, 0, input.length, chiperText, 0);

            

            ctLenght += cipher.doFinal(chiperText, ctLenght);

            encrypt.setText(new String(chiperText));

        } catch (Exception e) {

            JOptionPane.showMessageDialog(null, e);

        }

    }             

------------------------------------------------------------Decription------------------------------------

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         

        try {

            cipher.init(Cipher.DECRYPT_MODE, key,ivSpec);

            byte[] plainText = new byte[cipher.getOutputSize(ctLenght)];

            int ptLength = cipher.update(chiperText, 0,ctLenght,plainText,0);

            

            ptLength += cipher.doFinal(plainText, ptLength);

            decrypt.setText(new String(plainText));

        } catch (Exception e) {

            JOptionPane.showMessageDialog(null, e);

        }

    }                                        

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