DES 加解密应用示例

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import junit.framework.TestCase;
import org.apache.commons.codec.binary.Base64;
import org.apache.commons.codec.binary.Hex;

public class DesCoder extends TestCase {
    
    /** 密钥 */
    private static final String DES_KEY = "12345678";
    
    /**
     * 测试 DES 加密解密字符串 
     * @author 张振伟 (2013-7-24)
     * @throws Exception
     */
    public static void desString() throws Exception {
        String data = "这是需要加密的数据";
        Key key = getKey(DES_KEY.getBytes());
        byte[] cryptograph = encryptByteArr(data.getBytes("GBK"), key);
        System.out.println(Arrays.toString(cryptograph));
        byte[] decryptData = decryptByteArr(cryptograph, key);
        System.out.println(new String(decryptData, "GBK"));
    }
    
    /**
     * 测试 DES 加密解密文件 
     * @author 张振伟 (2013-7-24)
     * @throws Exception
     */
    public static void desFile() throws Exception {
        String dataFilePath = "D:/data.txt";
        String cryptographFilePath = "D:/cryptographFilePath.txt";
        String decryptData = "D:/decryptData.txt";
        Key key = randomKey();
        encryptFile(new File(dataFilePath), new File(cryptographFilePath), key);
        decryptFile(new File(cryptographFilePath), new File(decryptData), key);
    }
    /**
     * 生成一个随机的 DES 密钥 
     * @author 张振伟 (2013-7-24)
     * @throws Exception
     */
    public static Key randomKey() throws Exception{
        KeyGenerator generator = KeyGenerator.getInstance("DES");
        SecretKey key = generator.generateKey();
        byte[] arrKey = key.getEncoded();
        System.out.println(Arrays.toString(arrKey));
        System.out.println("密钥 Base64 转码：" + Base64.encodeBase64String(arrKey));
        System.out.println("密钥 16 进制显示：" + Hex.encodeHexString(arrKey));
        return key;
    }
    
    /**
     * 根据 byte 数组获得密钥对象 
     * @author 张振伟 (2013-7-24)
     * @param arrKey
     * @return
     * @throws Exception
     */
    public static Key getKey(byte[] arrKey) throws Exception {
        // 实例化 DES 密钥材料 
        DESKeySpec spec = new DESKeySpec(arrKey);
        // 实例化 DES 密钥工厂 
        SecretKeyFactory factory = SecretKeyFactory.getInstance("DES");
        return factory.generateSecret(spec);
    }
    
    /**
     * 加密字节数组形式的数据 
     * @author 张振伟 (2013-7-24)
     * @param data
     * @param key
     * @return
     * @throws NoSuchAlgorithmException
     * @throws NoSuchPaddingException
     * @throws InvalidKeyException
     * @throws IllegalBlockSizeException
     * @throws BadPaddingException
     */
    public static byte[] encryptByteArr(byte[] data, Key key) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
        // using DES in ECB mode
        Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
        // 用密匙初始化 Cipher 对象 
        cipher.init(Cipher.ENCRYPT_MODE, key);
        return cipher.doFinal(data);
    }
    
    /**
     * 解密字节数组形式的密文 
     * @author 张振伟 (2013-7-24)
     * @param data
     * @param key
     * @return
     * @throws NoSuchAlgorithmException
     * @throws NoSuchPaddingException
     * @throws InvalidKeyException
     * @throws IllegalBlockSizeException
     * @throws BadPaddingException
     */
    public static byte[] decryptByteArr(byte[] data, Key key) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
        // using DES in ECB mode
        Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
        // 用密匙初始化 Cipher 对象 
        cipher.init(Cipher.DECRYPT_MODE, key);
        return cipher.doFinal(data);
    }
    
    /**
     * DES 加密文件 
     * @author 张振伟 (2013-7-24)
     * @param file 明文文件 
     * @param dest 加密后的密文文件 
     * @param key 密钥 
     * @throws NoSuchAlgorithmException
     * @throws NoSuchPaddingException
     * @throws InvalidKeyException
     * @throws IOException
     */
    public static void encryptFile(File file, File dest, Key key) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IOException {
        Cipher cipher = Cipher.getInstance("DES");
        cipher.init(Cipher.ENCRYPT_MODE, key);
        InputStream is = new FileInputStream(file);
        OutputStream out = new FileOutputStream(dest);
        CipherInputStream cis = new CipherInputStream(is, cipher);
        byte[] buffer = new byte[1024];
        int r;
        while ((r = cis.read(buffer)) > 0) {
            out.write(buffer, 0, r);
        }
        cis.close();
        is.close();
        out.close();
    }
    
    /**
     * DES 解密文件 
     * @author 张振伟 (2013-7-24)
     * @param file 需要解密的密文文件 
     * @param dest 解密出的明文文件 
     * @param key 密钥 
     * @throws NoSuchAlgorithmException
     * @throws NoSuchPaddingException
     * @throws InvalidKeyException
     * @throws IOException
     */
    public static void decryptFile(File file, File dest, Key key) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IOException {
        Cipher cipher = Cipher.getInstance("DES");
        cipher.init(Cipher.DECRYPT_MODE, key);
        InputStream is = new FileInputStream(file);
        OutputStream out = new FileOutputStream(dest);
        CipherInputStream cis = new CipherInputStream(is, cipher);
        byte[] buffer = new byte[1024];
        int r;
        while ((r = cis.read(buffer)) > 0) {
            out.write(buffer, 0, r);
        }
        cis.close();
        is.close();
        out.close();
    }
}