java 加密解密

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本文介绍了一个使用Java实现的DES（Data Encryption Standard）加密和解密算法的示例。该示例通过KeyGenerator生成密钥，并利用Cipher类进行加密与解密操作，展示了如何在Java中使用DES算法。

import java.security.InvalidKeyException;   
import java.security.NoSuchAlgorithmException;     

import javax.crypto.BadPaddingException;   
import javax.crypto.Cipher;   
import javax.crypto.IllegalBlockSizeException;   
import javax.crypto.KeyGenerator;   
import javax.crypto.NoSuchPaddingException;   
import javax.crypto.SecretKey;   

public class EncrypDES {   

    //KeyGenerator 提供对称密钥生成器的功能，支持各种算法   
    private KeyGenerator keygen;   
    //SecretKey 负责保存对称密钥   
    private SecretKey deskey;   
    //Cipher负责完成加密或解密工作   
    private Cipher c;   
    //该字节数组负责保存加密的结果   
    private byte[] cipherByte;   
    private final static String algorithm = "DESede";

    public EncrypDES() throws NoSuchAlgorithmException, NoSuchPaddingException{   
//        //Security.addProvider(new com.sun.crypto.provider.SunJCE());   
//        //实例化支持DES算法的密钥生成器(算法名称命名需按规定，否则抛出异常)   
//        keygen = KeyGenerator.getInstance(algorithm);   
//        //生成密钥   
//        deskey = keygen.generateKey();   
//        //生成Cipher对象,指定其支持的DESede算法   
        c = Cipher.getInstance(algorithm); 

    	 KeyGenerator _generator = KeyGenerator.getInstance("DESede");

    	 deskey = _generator.generateKey();
         _generator = null;
    }   

    /**  
     * 对字符串加密  
     *   
     * @param str  
     * @return  
     * @throws InvalidKeyException  
     * @throws IllegalBlockSizeException  
     * @throws BadPaddingException  
     */  
    public byte[] Encrytor(String str) throws InvalidKeyException,   
            IllegalBlockSizeException, BadPaddingException {   
        // 根据密钥，对Cipher对象进行初始化，ENCRYPT_MODE表示加密模式   
        c.init(Cipher.ENCRYPT_MODE, deskey);   
        byte[] src = str.getBytes();   
        // 加密，结果保存进cipherByte   
        cipherByte = c.doFinal(src);   
        return cipherByte;   
    }   

    /**  
     * 对字符串解密  
     *   
     * @param buff  
     * @return  
     * @throws InvalidKeyException  
     * @throws IllegalBlockSizeException  
     * @throws BadPaddingException  
     */  
    public byte[] Decryptor(byte[] buff) throws InvalidKeyException,   
            IllegalBlockSizeException, BadPaddingException {   
        // 根据密钥，对Cipher对象进行初始化，DECRYPT_MODE表示加密模式   
        c.init(Cipher.DECRYPT_MODE, deskey);   
        cipherByte = c.doFinal(buff);   
        return cipherByte;   
    }   

    /**  
     * @param args  
     * @throws NoSuchPaddingException   
     * @throws NoSuchAlgorithmException   
     * @throws BadPaddingException   
     * @throws IllegalBlockSizeException   
     * @throws InvalidKeyException   
     */  
    public static void main(String[] args) throws Exception {   
        EncrypDES de1 = new EncrypDES();   
        String msg ="郭XX-搞笑相声全集";  
        msg = "adfasfas";
        msg = "http://www.agrilink.cn";
        byte[] encontent = de1.Encrytor(msg);   
        byte[] decontent = de1.Decryptor(encontent);   
        System.out.println("明文是:" + msg);   
        System.out.println("加密后:" + new String(encontent));   
        System.out.println("解密后:" + new String(decontent));   
    }   

}