什么是RSA这里就不多说了，度娘上说的很详细，至于生成公钥私钥，建议使用linux来生成，前台使用公钥加密，后台使用私钥解密，这样只要私钥不泄露，黑客破解你的密码就只剩下理论上的可能；
一、首先前台
1、在你的登录页面引入一个js文件：jsencrypt.js，这个文件是用来在前台对用户名和密码进行RSA加密的
登陆页面代码如下：（自己测试用的页面，很low比，将就着看）
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<html>
<script src="/testRSA/js/jquery-2.0.3.min.js"></script>
<script src="/testRSA/js/jsencrypt.js"></script>
<body>
<h2>登录页面</h2>
<form action="session/login" method="post" id="loginForm">
用户名：<input type="text" name="username" id="username"><br>
密码：<input type="text" name="password" id="password"><br>
<input type="button" value="登陆" onclick="login();">
</form>
</body>
<script>
function login(){
var username = $("#username").val();
var password = $("#password").val();
var encrypt = new JSEncrypt();
var publicKey= "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDv3KdlnDqWXRcvAFy30QCgRzjB"+
"/816jOzfwk72lmD9IodUz9c0nqlCBxIUxCwQC9UF2a6aaj0sFLqOjFelNXKZB5Kc"+
"WlZTJhqrAUCaWJ4q/7ms34Befkm/9bp5LIU1KFmmeKQgqTjEEBA8JTeZOJu5tOlw"+
"kVAdJpKpH4JUZEr1bQIDAQAB";
encrypt.setPublicKey(publicKey);
$("#username").val(encrypt.encrypt(username));
$("#password").val(encrypt.encrypt(password));
console.log(encrypt.encrypt(username));
console.log(encrypt.encrypt(password));
$("#loginForm").submit();
}
</script>
</html>
二、在后台对接收的用户名和密码进行解密
package you.you.an.controller;
import com.jfinal.core.Controller;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.pkcs.RSAPrivateKeyStructure;
import org.bouncycastle.util.encoders.Base64;
import you.you.an.util.ConfigFileUtil;
import javax.crypto.Cipher;
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.spec.RSAPrivateKeySpec;
/**
*
*/
public class SessionController extends Controller{
// private static final Logger logger = Logger.getLogger(SessionController.class);
private static final String privateStr = ConfigFileUtil.getPrivateKey();
private static KeyFactory kf = null;
private static RSAPrivateKeyStructure asn1PrivKey = null;
private static RSAPrivateKeySpec rsaPrivKeySpec = null;
private static PrivateKey rsaPriKey = null;
private static Cipher cipher = null;
static {
try {
if (asn1PrivKey == null){
asn1PrivKey = new RSAPrivateKeyStructure((ASN1Sequence) ASN1Sequence.fromByteArray(Base64.decode(privateStr)));
if (rsaPrivKeySpec == null){
rsaPrivKeySpec = new RSAPrivateKeySpec(asn1PrivKey.getModulus(), asn1PrivKey.getPrivateExponent());
if (kf == null){
kf = KeyFactory.getInstance("RSA");
if (rsaPriKey == null){
rsaPriKey = kf.generatePrivate(rsaPrivKeySpec);
if (cipher == null){
cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, rsaPriKey);
}
}
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
public void login() {
String username = getPara("username");
String password = getPara("password");
System.out.println(username);
System.out.println(password);
try {
byte[] passwordByte = cipher.doFinal(Base64.decode(password));
byte[] usernameByte = cipher.doFinal(Base64.decode(username));
System.out.println("解密后密码为："+new String(passwordByte));
System.out.println("解密后用户名为："+new String(usernameByte));
} catch (Exception e) {
e.printStackTrace();
}
}
}
这里解释一下为什么要使用静态代码块来初始化Cipher对象，因为这个对象的初始化是非常慢的，即便是采用了静态，还是怕影响效率，最终采用了MD5来加密，上述方法是个好方法，但前提是得解决java环境下RSA的运行效率问题！
转载于:https://my.oschina.net/ayo123/blog/1543850