import java.security.*;

import javax.crypto.*;

import java.io.*;

//对称加密器
public class CipherMessage {
    private String algorithm; // 算法，如DES
    private Key key; // 根据算法对应的密钥
    private String plainText; // 明文

    KeyGenerator keyGenerator;
    Cipher cipher;

    // 函数进行初始化
    CipherMessage(String alg, String msg) {
        algorithm = alg;
        plainText = msg;
    }

    // 加密函数，将原文加密成密文
    public byte[] CipherMsg() {
        byte[] cipherText = null;

        try {
            // 生成Cipher对象
            cipher = Cipher.getInstance(algorithm);
            // 用密钥加密明文(plainText),生成密文(cipherText)
            cipher.init(Cipher.ENCRYPT_MODE, key); // 操作模式为加密(Cipher.ENCRYPT_MODE),key为密钥
            cipherText = cipher.doFinal(plainText.getBytes()); // 得到加密后的字节数组
            // String str = new String(cipherText);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return cipherText;
    }

    // 解密函数，将密文解密回原文
    public String EncipherMsg(byte[] cipherText, Key k) {
        byte[] sourceText = null;

        try {
            cipher.init(Cipher.DECRYPT_MODE, k); // 操作模式为解密,key为密钥
            sourceText = cipher.doFinal(cipherText);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return new String(sourceText);

    }

    // 生成密钥
    public Key initKey() {
        try {
            // 初始化密钥key
            keyGenerator = KeyGenerator.getInstance(algorithm);
            keyGenerator.init(56); // 选择DES算法,密钥长度必须为56位
            key = keyGenerator.generateKey(); // 生成密钥
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return key;
    }

    /*
     * //从新设置密钥 public void setKey(Key k){ key = k; }
     */

    // 获取Key类型的密钥
    public Key getKey() {
        return key;
    }

    // 获取Key类型的密钥
    public Key getKey(byte[] k) {
        try {
            key = cipher.unwrap(k, algorithm, Cipher.DECRYPT_MODE);
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return key;
    }

    // 获取密钥包装成byte[]类型的
    public byte[] getBinaryKey(Key k) {
        byte[] bk = null;
        try {
            bk = cipher.wrap(k);
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return bk;
    }
}

import java.security.*;

import javax.crypto.*;

import java.io.*;

public class TestMain {

    public static void main(String[] args) {
        String algorithm = "DES"; // 定义加密算法,可用 DES,DESede,Blowfish
        String message = "Hello World. 这是待加密的信息"; // 生成个DES密钥
        Key key;

        CipherMessage cm = new CipherMessage(algorithm, message);
        key = cm.initKey();
        byte[] msg = cm.CipherMsg();
        System.out.println("加密后的密文为：" + new String(msg));
        // System.out.println("密钥为："+new String(cm.getBinaryKey(key)));

        /*byte[] bk = cm.getBinaryKey(key);
        System.out.println(bk);
        
        for (int i = 0; i < bk.length; i++)
            System.out.print(bk[i]);*/
        System.out.println(cm.getBinaryKey(key));
        System.out.println("解密密文为：" + cm.EncipherMsg(msg, key));

    }

}

    // 获取Key类型的密钥
    public Key getKey(byte[] k) {
        try {
            key = cipher.unwrap(k, algorithm, Cipher.DECRYPT_MODE);
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return key;
    }