java加密算法

不可逆加密

MD5加密

package com.system.util;

import java.security.MessageDigest;

public class MD5Util {
    public final static String MD5(String s) {
        char hexDigits[]={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};       
        try {
            byte[] btInput = s.getBytes();
            // 获得MD5摘要算法 MessageDigest 对象
            MessageDigest mdInst = MessageDigest.getInstance("MD5");
            // 使用指定的字节更新摘要
            mdInst.update(btInput);
            // 获得密文
            byte[] md = mdInst.digest();
            // 把密文转换成十六进制的字符串形式
            int j = md.length;
            char str[] = new char[j * 2];
            int k = 0;
            for (int i = 0; i < j; i++) {
                byte byte0 = md[i];
                str[k++] = hexDigits[byte0 >>> 4 & 0xf];
                str[k++] = hexDigits[byte0 & 0xf];
            }
            return new String(str);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
}

对称加密

DES加密

package com.gmtx.system.tools;

import java.security.SecureRandom;
import java.util.Random;
import javax.crypto.*;
import javax.crypto.spec.DESKeySpec;
import org.apache.commons.codec.binary.Base64;

/**
 DES加密介绍
 DES是一种对称加密算法，所谓对称加密算法即：加密和解密使用相同密钥的算法。DES加密算法出自IBM的研究，
 后来被美国政府正式采用，之后开始广泛流传，但是近些年使用越来越少，因为DES使用56位密钥，以现代计算能力，
 24小时内即可被破解。虽然如此，在某些简单应用中，我们还是可以使用DES加密算法
 注意：DES加密和解密过程中，密钥长度都必须是8的倍数
 */
public class DES {

    public static void main(String[] args) throws Exception {
        //动态创建16位秘钥,可以写死
        String password = createSecKey(16);
        System.out.println(password);

        String str = "测试内容";
        /*测试加密*/
        String rs = encrypt(str, password);
        System.out.println("加密后: "+rs);

        /*测试解密*/
        String rs_des = decrypt(rs,password);
        System.out.println("解密后: "+rs_des);

    }

    private static String[] ss = { "a", "b", "c", "d", "e", "f", "g", "h", "i",
            "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v",
            "w", "x", "y", "z", "A", "B", "C", "D", "E", "F", "G", "H", "I",
            "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V",
            "W", "X", "Y", "Z", "1", "2", "3", "4", "5", "6", "7", "8", "9",
            "0" };

    /**
     * 根据长度生成密钥
     * @param length 长度须是8
     * @return
     * @throws Exception
     */
    public static String createSecKey(int length) {
        if (length % 8 != 0) {
            return null;
        }
        String result = "";
        for (int i = 0; i < length; i++) {
            Random r = new Random();
            int n = r.nextInt(ss.length);
            result += ss[n];
        }
        return result;
    }

    /**
     * 加密
     * @param data 待加密数据
     * @param key  秘钥
     * @return
     * @throws Exception
     */
    public static String encrypt(String data, String key){
        try {
            byte[] bt = encrypt(data.getBytes("utf-8"), key);
            String strs = Base64.encodeBase64String(bt);
            return strs;
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return "";
    }

    /**
     * 解密
     * @param data 待解密字符串
     * @param key 秘钥
     * @return
     * @throws Exception
     */
    public static String decrypt(String data, String key) throws Exception {
        byte[] buf = Base64.decodeBase64(data);
        byte[] bt = decrypt(buf, key);
        return new String(bt, "UTF-8");
    }

    /**
     * 加密 - byte数组
     * @param datasource
     * @param password
     * @return
     */
    private static byte[] encrypt(byte[] datasource, String password) {
        try {
            SecureRandom random = new SecureRandom();
            DESKeySpec desKey = new DESKeySpec(password.getBytes());
            //创建一个密匙工厂，然后用它把DESKeySpec转换成SecretKey
            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
            SecretKey securekey = keyFactory.generateSecret(desKey);
            //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, random);
            //现在，获取数据并加密
            //正式执行加密操作
            return cipher.doFinal(datasource);
        } catch (Throwable e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 解密 - byte数组
     * @param src 加密字符串的二进制数组
     * @param password 解密密码
     * @return 原字符串的二进制数组
     * @throws Exception
     */
    private static byte[] decrypt(byte[] src, String password) throws Exception {
        //DES算法要求有一个可信任的随机数源
        SecureRandom random = new SecureRandom();
        //创建一个DESKeySpec对象
        DESKeySpec desKey = new DESKeySpec(password.getBytes());
        //创建一个密匙工厂
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
        //将DESKeySpec对象转换成SecretKey对象
        SecretKey securekey = keyFactory.generateSecret(desKey);
        //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, random);
        // 真正开始解密操作
        return cipher.doFinal(src);
    }
}

测试内容