DES 加/解密工具

import java.security.SecureRandom;
 
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
 
/**
 * 加解密工具类
 * @author Winter Lau
 */
public class CryptUtils {
 
    private final static String DES = "DES";
    
    /**
     * 加密
     * @param src 数据源
     * @param key 密钥，长度必须是8的倍数
     * @return    返回加密后的数据
     * @throws Exception
     */
    public static byte[] encrypt(byte[] src, byte[] key) throws RuntimeException {
        //DES算法要求有一个可信任的随机数源
        try{
            SecureRandom sr = new SecureRandom();
            // 从原始密匙数据创建DESKeySpec对象
            DESKeySpec dks = new DESKeySpec(key);
            // 创建一个密匙工厂，然后用它把DESKeySpec转换成
            // 一个SecretKey对象
            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
            SecretKey securekey = keyFactory.generateSecret(dks);
            // Cipher对象实际完成加密操作
            Cipher cipher = Cipher.getInstance(DES);
            // 用密匙初始化Cipher对象
            cipher.init(Cipher.ENCRYPT_MODE, securekey, sr);
            // 现在，获取数据并加密
            // 正式执行加密操作
            return cipher.doFinal(src);
        }catch(Exception e){
            throw new RuntimeException(e);
        }
    }
     
    /**
     * 解密
     * @param src   数据源
     * @param key   密钥，长度必须是8的倍数
     * @return      返回解密后的原始数据
     * @throws Exception
     */
    public static byte[] decrypt(byte[] src, byte[] key) throws RuntimeException {
        try{
            // DES算法要求有一个可信任的随机数源
            SecureRandom sr = new SecureRandom();
            // 从原始密匙数据创建一个DESKeySpec对象
            DESKeySpec dks = new DESKeySpec(key);
            // 创建一个密匙工厂，然后用它把DESKeySpec对象转换成
            // 一个SecretKey对象
            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
            SecretKey securekey = keyFactory.generateSecret(dks);
            // Cipher对象实际完成解密操作
            Cipher cipher = Cipher.getInstance(DES);
            // 用密匙初始化Cipher对象
            cipher.init(Cipher.DECRYPT_MODE, securekey, sr);
            // 现在，获取数据并解密
            // 正式执行解密操作
            return cipher.doFinal(src);
        }catch(Exception e){
            throw new RuntimeException(e);
        }
    }
    /**
     * 数据解密
     * @param data
     * @param key 密钥
     * @return
     * @throws Exception
     */
    public final static String decrypt(String data, String key) throws Exception{
        return new String(decrypt(hex2byte(data.getBytes()),key.getBytes()));
    }
    /**
     * 数据加密
     * @param data
     * @param key 密钥
     * @return
     * @throws Exception
     */
    public final static String encrypt(String data, String key){
        if(data!=null)
        try {
            return byte2hex(encrypt(data.getBytes(),key.getBytes()));
        }catch(Exception e) {
            throw new RuntimeException(e);
        }
        return null;
    }
 
    /**
     * 二行制转字符串
     * @param b
     * @return
     */
    private static String byte2hex(byte[] b) {
        StringBuilder hs = new StringBuilder();
        String stmp;
        for (int n = 0; b!=null && n < b.length; n++) {
            stmp = Integer.toHexString(b[n] & 0XFF);
            if (stmp.length() == 1)
                hs.append('0');
            hs.append(stmp);
        }
        return hs.toString().toUpperCase();
    }
     
    private static byte[] hex2byte(byte[] b) {
        if((b.length%2)!=0)
            throw new IllegalArgumentException();
        byte[] b2 = new byte[b.length/2];
        for (int n = 0; n < b.length; n+=2) {
            String item = new String(b,n,2);
            b2[n/2] = (byte)Integer.parseInt(item,16);
        }
        return b2;
    }
    
    public static void main(String[] args) {
		try {
			String cs = CryptUtils.encrypt("abcd", "12345678");
			String decs = CryptUtils.decrypt("94D4436BC3B5B693FEB959B7D4642FCB", "12345678");
			System.out.println("cs = "+cs);
			System.out.println("decs = "+decs);
			System.out.println("B1E1429AD11B22FB".length());
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
     
}