JAVAX crypto sealedobject example

 

Here is an example of using SealedObject in the javax. crypto package to encrypt and decrypt an object:

import java.io.Serializable;

import java. security.Key;

import javax. crypto.Cipher;

import javax. crypto.SealedObject;

public class Encryptor {

  private Cipher cipher;

  public Encryptor(Key key) throws Exception {

    cipher = Cipher.getInstance("AES");

    cipher.init(Cipher.ENCRYPT_MODE, key);

  }

  public SealedObject encrypt(Serializable object) throws Exception {

    return new SealedObject(object, cipher);

  }

}

public class Decryptor {

  private Cipher cipher;

  public Decryptor(Key key) throws Exception {

    cipher = Cipher.getInstance("AES");

    cipher.init(Cipher.DECRYPT_MODE, key);

  }

  public Object decrypt(SealedObject sealedObject) throws Exception {

    return sealedObject.getObject(cipher);

  }

}

To use these classes, you would first create an instance of Encryptor with a secret key and then use the encrypt method to encrypt an object and get a SealedObject. You can then send the SealedObject to someone else, who can use an instance of Decryptor initialized with the same secret key to decrypt the object.

Note that SealedObject only works with objects that implement the Serializable interface, as it requires the object to be converted to a stream of bytes in order to be encrypted.

Here's an example of how to use the SealedObject class in the javax.crypto package to encrypt and decrypt an object in Java:

import javax.crypto.Cipher;

import javax.crypto.SealedObject;

import javax.crypto.SecretKey;

import javax.crypto.SecretKeyFactory;

import javax.crypto.spec.PBEKeySpec;

import javax.crypto.spec.PBEParameterSpec;

import java.security.spec.KeySpec;

public class SealedObjectExample {

    private static Cipher ecipher;

    private static Cipher dcipher;

    // 8-byte Salt

    private static byte[] salt = {

        (byte) 0xA9, (byte) 0x9B, (byte) 0xC8, (byte) 0x32,

        (byte) 0x56, (byte) 0x34, (byte) 0xE3, (byte) 0x03

    };

    // Iteration count

    private static int iterationCount = 19;

    public static void main(String[] args) throws Exception {

        String secretString = "This is a secret message";

        // Create the key

        KeySpec keySpec = new PBEKeySpec("myPassword".toCharArray(), salt, iterationCount);

        SecretKey key = SecretKeyFactory.getInstance("PBEWithMD5AndDES").generateSecret(keySpec);

        // Create the sealed object

        SealedObject sealedObject = new SealedObject(secretString, ecipher);

        // Encrypt the object

        ecipher = Cipher.getInstance(key.getAlgorithm());

        ecipher.init(Cipher.ENCRYPT_MODE, key, new PBEParameterSpec(salt, iterationCount));

        byte[] encryptedObject = ecipher.doFinal(sealedObject.getObject(key).toString().getBytes());

        // Decrypt the object

        dcipher = Cipher.getInstance(key.getAlgorithm());

        dcipher.init(Cipher.DECRYPT_MODE, key, new PBEParameterSpec(salt, iterationCount));

        String decryptedObject = (String) sealedObject.getObject(key);

        System.out.println("Original object: " + secretString);

        System.out.println("Encrypted object: " + encryptedObject.toString());

        System.out.println("Decrypted object: " + decryptedObject);

    }

}

The SealedObject class is used to encrypt an object and store it in a secure manner. It can only be decrypted with the correct key, which is generated using a password-based key derivation function (PBKDF). In this example, the key is generated using the PBEWithMD5AndDES algorithm and a salt value, and the object is encrypted using the PBEWithMD5AndDES algorithm as well. The encrypted object is then decrypted using the same key and algorithm.

Related Reading