java加解密算法--DES

• ECB

import javax.crypto.*;

import javax.crypto.spec.DESKeySpec;

import java.io.IOException;

import java.security.InvalidAlgorithmParameterException;

import java.security.InvalidKeyException;

import java.security.NoSuchAlgorithmException;

import java.security.spec.InvalidKeySpecException;

public class Decrypt {

    public static byte[] initSecretKey() throws NoSuchAlgorithmException {

        //指定算法秘钥生成器

        KeyGenerator kg = KeyGenerator.getInstance("des");

        //初始化秘钥生成器，使其具有确定到秘钥大小

        kg.init(56);

        //生成秘钥

        SecretKey secretkey = kg.generateKey();

        return secretkey.getEncoded();

    }

    public static byte[] encrypt(byte[] key, String src) throws InvalidKeyException, NoSuchAlgorithmException, InvalidKeySpecException, NoSuchPaddingException, BadPaddingException, IllegalBlockSizeException, InvalidAlgorithmParameterException {

        //jdk初始化秘钥转化des秘钥

        DESKeySpec desKeySpec = new DESKeySpec(key);

        //创建秘钥工厂实例

        SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance("des");

        //生成秘钥

        SecretKey secretKey = secretKeyFactory.generateSecret(desKeySpec);

        /**

         * 加密实际操作Cipher

         */

        //创建Cipher对象

        Cipher cipher = Cipher.getInstance("des/cbc/PKCS5Padding");

        //初始化Cipher

        cipher.init(Cipher.ENCRYPT_MODE,secretKey);

        byte[] data = src.getBytes();

        //加密

        byte[] encryptedData = cipher.doFinal(data);

        return encryptedData;

    }

    public static void main(String[] args) throws NoSuchAlgorithmException, IllegalBlockSizeException, NoSuchPaddingException, BadPaddingException, InvalidKeySpecException, InvalidKeyException, IOException, InvalidAlgorithmParameterException {

        //byte[] secretKey = initSecretKey();

        //或者代码中约定key

        String key = "YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4";

        byte[] secretKey = key.getBytes();

        String str = "abc";

        byte[] encryptedData = encrypt(secretKey, str);

        String decrypteData = decrypt(secretKey, encryptedData);

    }

    public static String decrypt(byte[] key,byte[] encryptedData) throws InvalidKeyException, NoSuchAlgorithmException, InvalidKeySpecException, NoSuchPaddingException, BadPaddingException, IllegalBlockSizeException, InvalidAlgorithmParameterException {

        //jdk初始化秘钥转化des秘钥

        DESKeySpec desKeySpec = new DESKeySpec(key);

        //创建秘钥工厂实例

        SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance("des");

        //生成秘钥

        SecretKey secretKey = secretKeyFactory.generateSecret(desKeySpec);

        /** * 解密实际操作Cipher */

        //创建Cipher对象

        Cipher cipher = Cipher.getInstance("des/cbc/PKCS5Padding");

        //初始化Cipher

        cipher.init(Cipher.DECRYPT_MODE,secretKey);

        //加密

        byte[] dencryptedData = cipher.doFinal(encryptedData);

        return new String(dencryptedData);

    }

}　　　

• CBC

与ECB差别，加解密都要使用初始化向量，且初始化向量一致　　　

import javax.crypto.*;

import javax.crypto.spec.DESKeySpec;

import javax.crypto.spec.IvParameterSpec;

import java.io.IOException;

import java.security.InvalidAlgorithmParameterException;

import java.security.InvalidKeyException;

import java.security.NoSuchAlgorithmException;

import java.security.spec.InvalidKeySpecException;

public class encrypt {

    public static byte[] initSecretKey() throws NoSuchAlgorithmException {

        //指定算法秘钥生成器

        KeyGenerator kg = KeyGenerator.getInstance("des");

        //初始化秘钥生成器，使其具有确定到秘钥大小

        kg.init(56);

        //生成秘钥

        SecretKey secretkey = kg.generateKey();

        return secretkey.getEncoded();

    }

    public static byte[] encrypt(byte[] key, String src,byte[] keyIv) throws InvalidKeyException, NoSuchAlgorithmException, InvalidKeySpecException, NoSuchPaddingException, BadPaddingException, IllegalBlockSizeException, InvalidAlgorithmParameterException {

        //jdk初始化秘钥转化des秘钥

        DESKeySpec desKeySpec = new DESKeySpec(key);

        //创建秘钥工厂实例

        SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance("des");

        //生成秘钥

        SecretKey secretKey = secretKeyFactory.generateSecret(desKeySpec);

        /**

         * 加密实际操作Cipher

         */

        //创建Cipher对象

        Cipher cipher = Cipher.getInstance("des/cbc/PKCS5Padding");

        //创建初始化向量

        IvParameterSpec iv = new IvParameterSpec(keyIv);

        //初始化Cipher

        cipher.init(Cipher.ENCRYPT_MODE,secretKey,iv);

        byte[] data = src.getBytes();

        //加密

        byte[] encryptedData = cipher.doFinal(data);

        return encryptedData;

    }

    public static void main(String[] args) throws NoSuchAlgorithmException, IllegalBlockSizeException, NoSuchPaddingException, BadPaddingException, InvalidKeySpecException, InvalidKeyException, IOException, InvalidAlgorithmParameterException {

        //byte[] secretKey = initSecretKey();

        //或者代码中约定key

        String key = "YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4";

        byte[] secretKey = key.getBytes();

        byte[] iv = {1, 2, 3, 4, 5, 6, 7, 8};

        String str = "abc";

        byte[] encryptedData = encrypt(secretKey, str,iv);

        String decrypteData = decrypt(secretKey, encryptedData,iv);

    }

    public static String decrypt(byte[] key,byte[] encryptedData,byte[] keyIv) throws InvalidKeyException, NoSuchAlgorithmException, InvalidKeySpecException, NoSuchPaddingException, BadPaddingException, IllegalBlockSizeException, InvalidAlgorithmParameterException {

        //jdk初始化秘钥转化des秘钥

        DESKeySpec desKeySpec = new DESKeySpec(key);

        //创建秘钥工厂实例

        SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance("des");

        //生成秘钥

        SecretKey secretKey = secretKeyFactory.generateSecret(desKeySpec);

        /** * 解密实际操作Cipher */

        //创建Cipher对象

        Cipher cipher = Cipher.getInstance("des/cbc/PKCS5Padding");

        //创建初始化向量

        IvParameterSpec iv = new IvParameterSpec(keyIv);

        //初始化Cipher

        cipher.init(Cipher.DECRYPT_MODE,secretKey,iv);

        //加密

        byte[] dencryptedData = cipher.doFinal(encryptedData);

        return new String(dencryptedData);

    }

}

　　

DES与3DES同样到工作模式和填充模式相同，它们加解密区别：

• jdk初始化秘钥转化des秘钥

　　DES：

DESKeySpec desKeySpec = new DESKeySpec(key);

　　3DES：

DESedeKeySpec spec = new DESedeKeySpec(key);

• 创建秘钥工厂实例　　

　　DES：

SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance("des");

　　3DES：

SecretKeyFactory keyfactory = SecretKeyFactory.getInstance("desede");

• 密钥长度

　　DES：56

　　3DES：168