客户端JavaScript加密数据，服务端Java解密数据

原文：http://blog.csdn.net/peterwanghao/article/details/43303807

在普通的页面提交时，如果没有使用SSL，提交的数据将使用纯文本的方式发送。如果使用抓包工具可以轻易地截获一些关键数据。

jCryption是一个jQuery插件，能够加密由Forms提交的POST/GET数据。官网地址：http://www.jcryption.org/

未加密处理的效果如下：可很容易地看到登录时的用户名和口令。

使用jCryption后效果如下，提交的数据为密文。

本例中服务端使用Java进行解密，使用了一个开源项目JavaCription，官网地址：https://jcryptionforjava.wordpress.com/。实现了针对jCryption2.0的Java解密。

处理机制如下：

1、客户端从服务端请求一个RSA公钥

2、客户端产生一个随机数作为AES密钥，用RSA公钥进行加密，发送到服务端

3、服务端用RSA私钥进行解密，同时将AES密钥保持到会话中

4、服务端用AES算法加密AES密钥并送回给客户端

5、客户端用AES算法解密，并与本地保存的AES密钥做比对，如果相符就认为服务端是合法的

6、客户端提交数据，数据用AES密钥进行加密

在此版本里为提供效率，只使用RSA非对称算法进行密钥交换，数据的加解密使用AES对称算法。

客户端

引入两个js文件

<script type="text/JavaScript" src="js/jquery-2.1.3.min.js"></script>
<script type="text/javascript" src="js/jquery.jcryption.js"></script>

表单加密，设定两个地址：1）获取公钥 2）握手交换AES密钥

<script type="text/javascript">
$(function() {
$("#form1").jCryption();
});
$.jCryption.defaultOptions.getKeysURL="encrypt?generateKeyPair=true";
$.jCryption.defaultOptions.handshakeURL="encrypt?handshake=true";
</script>

服务端

密钥服务Servlet

public class CryptoServlet extends HttpServlet{
    /**
     * serialVersionUID
     */
    private static final long serialVersionUID = 4510110365995157499L;

    /**
     * Handles a POST request
     * 
     * @see HttpServlet
     */
    public void doPost(HttpServletRequest req, HttpServletResponse res) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) res;

        /** Generates a KeyPair for RSA **/
        if (req.getParameter("generateKeyPair") != null && req.getParameter("generateKeyPair").equals("true")) {

            JCryption jc = new JCryption();
            KeyPair keys = jc.getKeyPair();
            request.getSession().getServletContext().setAttribute("jCryptionKeys", keys);
            String e = jc.getPublicExponent();
            String n = jc.getKeyModulus();
            String md = String.valueOf(jc.getMaxDigits());

            /** Sends response **/
            PrintWriter out = response.getWriter();
            out.print("{"e":"" + e + "","n":"" + n + "","maxdigits":"" + md + ""}");
            return;
        }
        /** jCryption handshake **/
        else if (req.getParameter("handshake") != null && req.getParameter("handshake").equals("true")) {

            /** Decrypts password using private key **/
            JCryption jc = new JCryption((KeyPair) request.getSession().getServletContext()
                    .getAttribute("jCryptionKeys"));
            String a = req.getParameter("key");
            System.out.println(a);
            String key = jc.decrypt(req.getParameter("key"));

            request.getSession().getServletContext().removeAttribute("jCryptionKeys");
            request.getSession().getServletContext().setAttribute("jCryptionKey", key);

            /** Encrypts password using AES **/
            String ct = AesCtr.encrypt(key, key, 256);

            /** Sends response **/
            PrintWriter out = response.getWriter();
            out.print("{"challenge":"" + ct + ""}");

            return;
        }
        /** jCryption request to decrypt a String **/
        else if (req.getParameter("decryptData") != null && req.getParameter("decryptData").equals("true")
                && req.getParameter("jCryption") != null) {

            /** Decrypts the request using password **/
            String key = (String) request.getSession().getServletContext().getAttribute("jCryptionKey");

            String pt = AesCtr.decrypt(req.getParameter("jCryption"), key, 256);

            /** Sends response **/
            PrintWriter out = response.getWriter();
            out.print("{"data":"" + pt + ""}");
            return;
        }
        /** jCryption request to encrypt a String **/
        else if (req.getParameter("encryptData") != null && req.getParameter("encryptData").equals("true")
                && req.getParameter("jCryption") != null) {

            /** Encrypts the request using password **/
            String key = (String) request.getSession().getServletContext().getAttribute("jCryptionKey");

            String ct = AesCtr.encrypt(req.getParameter("jCryption"), key, 256);

            /** Sends response **/
            PrintWriter out = response.getWriter();
            out.print("{"data":"" + ct + ""}");
            return;
        }
        /** A test request from jCryption **/
        else if (req.getParameter("decryptTest") != null && req.getParameter("decryptTest").equals("true")) {

            /** Encrypts a timestamp **/
            String key = (String) request.getSession().getServletContext().getAttribute("jCryptionKey");

            String date = DateFormat.getInstance().format(new Date());

            String ct = AesCtr.encrypt(date, key, 256);

            /** Sends response **/
            PrintWriter out = response.getWriter();
            out.print("{"encrypted":"" + ct + "", "unencrypted":"" + date + ""}");
            return;
        }
    }

    /**
     * Handles a GET request
     * 
     * @see HttpServlet
     */
    public void doGet(HttpServletRequest req, HttpServletResponse res) throws IOException, ServletException {
        doPost(req, res);
    }
}

过虑器，进行数据解密

密文：5QN8EsTjylTGSyvrmYGXDUD/MjF3qcl58pZtI7xhCk5HMUYFjf7kJe/leQLAuqzW4dPUNw==
明文：loginName=admin&password=admin&Submit=提交

public class SecureFilter implements Filter{
    private FilterConfig conf;
    
    public void destroy() {
        // TODO Auto-generated method stub
        
    }

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException,
            ServletException {
        String jCryption = request.getParameter("jCryption");
        System.out.println(jCryption);
        String key = (String) conf.getServletContext().getAttribute("jCryptionKey");

        String source = AesCtr.decrypt(jCryption, key, 256);
        System.out.println(source);
        
        String[] params = source.split("&");
        for(int i=0;i<params.length;i++){
            String [] aparam = params[i].split("=");
            request.setAttribute(aparam[0], aparam[1]);
        }
        
        chain.doFilter(request, response);
        
    }

    public void init(FilterConfig filterConfig) throws ServletException {
        this.conf = filterConfig;
        
    }

}

处理器，从request.getAttribute中获取数据

String loginName = passwordAuthcInfo.getLoginName();
        String loginPassword = passwordAuthcInfo.getPassword();
        if(loginName == null && loginPassword == null){
            loginName = (String)request.getAttribute("loginName");
            loginPassword = (String)request.getAttribute("password");
        }