java加密與解密-對稱算法DES（4）

對稱加密算法

​ 對於大多數對稱 加密算法而言，解密算法是加密算法的逆運算，加密密鑰和解密密鑰相同，對稱加密算法家族以DES加密算法最具有代表性，由於密鑰長度的不滿足，也在此基礎上衍生出了DESede算法（3DES算法）

• DES算法的實現：

**
 * @Author: zxx
 * @Description: DES加解密
 */
public class DESUtil {

    /**
     * 算法常量： DES
     */
    private static final String ALGORITHM_DES = "DES";
    /**
     * 加密/解密算法/工作模式/填充方式
     */
    private static final String ALGORITHM_CIPHER = "DES/ECB/PKCS5Padding";

    /**
     * 轉換密鑰
     * @param key
     * @return
     */
    private static Key toKey(byte[] key){
        SecretKey secretKey = null;
        try {
            //實例化DES密鑰材料
            DESKeySpec dks = new DESKeySpec(key);
            //實例化工廠密鑰
            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM_DES);
            //生成祕密密鑰
            secretKey = keyFactory.generateSecret(dks);
        }catch (Exception e){
            e.printStackTrace();
        }
       return  secretKey;
    }

    /**
     * 加密
     * @param data 加密數據
     * @param key 密鑰
     * @return
     */
    public static byte[] encrypt(byte[] data,byte[] key){
        byte[] rbyte = null;
        try {
            Key k=toKey(key);
            //加密類實例化
            Cipher cipher=Cipher.getInstance(ALGORITHM_DES);
            cipher.init(Cipher.ENCRYPT_MODE, k);
            //執行加密操作
            rbyte = cipher.doFinal(data);
        }catch (Exception e){
            e.printStackTrace();
        }
        return rbyte;
    }


    /**
     * 解密
     * @param data 解密數據
     * @param key 密鑰
     * @return
     */
    public static byte[] decrypt(byte[] data,byte[] key){
        byte[] rbyte = null;
        try {
            Key k=toKey(key);
            //加密類實例化
            Cipher cipher=Cipher.getInstance(ALGORITHM_DES);
            cipher.init(Cipher.DECRYPT_MODE, k);
            //執行加密操作
            rbyte = cipher.doFinal(data);
        }catch (Exception e){
            e.printStackTrace();
        }
        return rbyte;
    }

}

• 3DES加密解密實現

/**
 * @Author: zxx
 * @Description: 3DES加密解密
 */
public class ThreeDESUtil {

    /**
     * 算法常量： DES
     */
    private static final String ALGORITHM_DES = "DESede";
    /**
     * 加密/解密算法/工作模式/填充方式
     */
    private static final String ALGORITHM_CIPHER = "DESede/ECB/PKCS5Padding";


    /**
     * 轉換密鑰
     * @param key
     * @return
     */
    private static Key toKey(byte[] key){
        SecretKey secretKey = null;
        try {
            //實例化DES密鑰材料
            DESedeKeySpec dks = new DESedeKeySpec(key);
            //實例化工廠密鑰
            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM_DES);
            //生成祕密密鑰
            secretKey = keyFactory.generateSecret(dks);
        }catch (Exception e){
            e.printStackTrace();
        }
       return  secretKey;
    }

    /**
     * 加密
     * @param data 加密數據
     * @param key 密鑰
     * @return
     */
    public static byte[] encrypt(byte[] data,byte[] key){
        byte[] rbyte = null;
        try {
            Key k=toKey(key);
            //加密類實例化
            Cipher cipher=Cipher.getInstance(ALGORITHM_CIPHER);
            cipher.init(Cipher.ENCRYPT_MODE, k);
            //執行加密操作
            rbyte = cipher.doFinal(data);
        }catch (Exception e){
            e.printStackTrace();
        }
        return rbyte;
    }


    /**
     * 解密
     * @param data 解密數據
     * @param key 密鑰
     * @return
     */
    public static byte[] decrypt(byte[] data,byte[] key){
        byte[] rbyte = null;
        try {
            Key k=toKey(key);
            //加密類實例化
            Cipher cipher=Cipher.getInstance(ALGORITHM_CIPHER);
            cipher.init(Cipher.DECRYPT_MODE, k);
            //執行加密操作
            rbyte = cipher.doFinal(data);
        }catch (Exception e){
            e.printStackTrace();
        }
        return rbyte;
    }

}

• 測試

/**
 * @Author: zxx
 * @Description: 測試
 */
public class DESTest {
    public static void main(String[] args) throws Exception {

        String deskey = "12345678901234567890123456789012";
        String desstr = "des要加密的數據";
        byte[] desdatastr = desstr.getBytes("utf-8");

        byte[] desenstr = DESUtil.encrypt(desdatastr,deskey.getBytes("utf-8"));
        System.out.println(Base64.encodeBase64String(desenstr));
        byte[] desdestr = DESUtil.decrypt(desenstr,deskey.getBytes("utf-8"));
        String dess = new String(desdestr,"utf-8");
        System.out.println(dess.toString());


        String key = "123456789012345678901234";
        String str = "3des要加密的數據";
        byte[] datastr = str.getBytes("utf-8");

        byte[] enstr = ThreeDESUtil.encrypt(datastr,key.getBytes("utf-8"));
        System.out.println(Base64.encodeBase64String(enstr));
        byte[] destr = ThreeDESUtil.decrypt(enstr,key.getBytes("utf-8"));
        String s = new String(destr,"utf-8");
        System.out.println(s.toString());
    }
}