EncryptUtils.java

package com.minggo.pluto.util;

import android.annotation.SuppressLint;

import java.security.Key;
import java.security.MessageDigest;
import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.Cipher;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.spec.IvParameterSpec;

/**
 * 加密工具类
 * @author minggo
 * @time 2014-12-2下午2:15:02
 */
@SuppressLint({ "DefaultLocale", "TrulyRandom" })
public class EncryptUtils {

	public static final String ALGORITHM_DES = "DES/CBC/PKCS5Padding";
	
	public static final String PARSE_RULE_KEY = "pluto";
	
	/**
	 * md5加密
	 * @param str
	 * @return
	 */
	public String getMD5Str(String str) {

		MessageDigest md5 = null;
		try {
			md5 = MessageDigest.getInstance("MD5");
		} catch (Exception e) {
			e.printStackTrace();
			return "";
		}

		char[] charArray = str.toCharArray();
		byte[] byteArray = new byte[charArray.length];

		for (int i = 0; i < charArray.length; i++) {
			byteArray[i] = (byte) charArray[i];
		}
		byte[] md5Bytes = md5.digest(byteArray);

		StringBuffer hexValue = new StringBuffer();
		for (int i = 0; i < md5Bytes.length; i++) {
			int val = ((int) md5Bytes[i]) & 0xff;
			if (val < 16) {
				hexValue.append("0");
			}
			hexValue.append(Integer.toHexString(val));
		}
		return hexValue.toString();

	}
	
	/**
     * DES算法，加密
     *
     * @param data 待加密字符串
     * @param key  加密私钥，长度不能够小于8位
     * @return 加密后的字节数组，一般结合Base64编码使用
     * @throws InvalidAlgorithmParameterException 
     * @throws Exception 
     */
    public static String encode(String key,String data) {
    	if(data == null)
    		return null;
    	try{
	    	DESKeySpec dks = new DESKeySpec(key.getBytes());	    	
	    	SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
	        //key的长度不能够小于8位字节
	        Key secretKey = keyFactory.generateSecret(dks);
	        Cipher cipher = Cipher.getInstance(ALGORITHM_DES);
	        IvParameterSpec iv = new IvParameterSpec(key.getBytes());
	        AlgorithmParameterSpec paramSpec = iv;
	        cipher.init(Cipher.ENCRYPT_MODE, secretKey,paramSpec);           
	        byte[] bytes = cipher.doFinal(data.getBytes());            
	        return byte2hex(bytes);
    	}catch(Exception e){
    		e.printStackTrace();
    		return data;
    	}
    }

    /**
     * DES算法，解密
     *
     * @param data 待解密字符串
     * @param key  解密私钥，长度不能够小于8位
     * @return 解密后的字节数组
     * @throws Exception 异常
     */
    public static String decode(String key,String data) {
    	if(data == null)
    		return null;
        try {
	    	DESKeySpec dks = new DESKeySpec(key.getBytes());
	    	SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
            //key的长度不能够小于8位字节
            Key secretKey = keyFactory.generateSecret(dks);
            Cipher cipher = Cipher.getInstance(ALGORITHM_DES);
            IvParameterSpec iv = new IvParameterSpec(key.getBytes());
            AlgorithmParameterSpec paramSpec = iv;
            cipher.init(Cipher.DECRYPT_MODE, secretKey, paramSpec);
            return new String(cipher.doFinal(hex2byte(data.getBytes())));
        } catch (Exception e){
    		e.printStackTrace();
    		return data;
        }
    }

	/**
	 * 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;
    }    
    
}