Java包Cipher类,关于DES加密有关问题

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;    }