关于使用JS前台加密、JAVA后台解密的RSA实现，RSA加密和签名

需求环境：

西安项目中，客户要求保护用户的密码信息，不允许在http中传递明文的密码信息。

 

实现：

用RSA非对称加密方式实现。后台生成rsa密钥对，然后在登陆页面设置rsa公钥，提交时用公钥加密密码，生成的密文传到后台，用私钥解密，获取密码明文。

这样客户端只需要知道rsa加密方式和公钥，前台不知道私钥是无法解密的，此解决方案还是相对比较安全的。

附件是参照网友资料的Java+JS的实现，放在这里供大家下载。访问方式/RSA/login.jsp。

需要到http://www.bouncycastle.org下载bcprov-jdk14-123.jar文件。

因为后台要转换成bigint，所以对明文长度有些限制：

总长度不超过126（1汉字长度为9），如下两个字符串：

阿送大法散得阿送大法散得阿送
1232132131231231232131232K1232132131231231232131232K1232132131231231232131232K1232132131231231232131232K1234567890123456789012

 

 

RSA速度  
 * 由于进行的都是大数计算，使得RSA最快的情况也比DES慢上100倍，无论 是软件还是硬件实现。  
 * 速度一直是RSA的缺陷。一般来说只用于少量数据 加密。

 

 

Util.java

 

 package RSA;

 /**
  *
  */

 import java.io.ByteArrayOutputStream;
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 import java.math.BigInteger;
 import java.security.KeyFactory;
 import java.security.KeyPair;
 import java.security.KeyPairGenerator;
 import java.security.NoSuchAlgorithmException;
 import java.security.PrivateKey;
 import java.security.PublicKey;
 import java.security.SecureRandom;
 import java.security.interfaces.RSAPrivateKey;
 import java.security.interfaces.RSAPublicKey;
 import java.security.spec.InvalidKeySpecException;
 import java.security.spec.RSAPrivateKeySpec;
 import java.security.spec.RSAPublicKeySpec;

 import javax.crypto.Cipher;

 /**
  * RSA 工具类。提供加密，解密，生成密钥对等方法。
  * 需要到http://www.bouncycastle.org下载bcprov-jdk14-123.jar。
  *
  */
 public class RSAUtil {

     private static String RSAKeyStore = "C:/RSAKey.txt";
     /**
      * * 生成密钥对 *
      *
      * @return KeyPair *
      * @throws EncryptException
      */
     public static KeyPair generateKeyPair() throws Exception {
         try {
             KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA",
                     new org.bouncycastle.jce.provider.BouncyCastleProvider());
             final int KEY_SIZE = 1024;// 没什么好说的了，这个值关系到块加密的大小，可以更改，但是不要太大，否则效率会低
             keyPairGen.initialize(KEY_SIZE, new SecureRandom());
             KeyPair keyPair = keyPairGen.generateKeyPair();

             System.out.println(keyPair.getPrivate());
             System.out.println(keyPair.getPublic());

             saveKeyPair(keyPair);
             return keyPair;
         } catch (Exception e) {
             throw new Exception(e.getMessage());
         }
     }

     public static KeyPair getKeyPair() throws Exception {
         FileInputStream fis = new FileInputStream(RSAKeyStore);
         ObjectInputStream oos = new ObjectInputStream(fis);
         KeyPair kp = (KeyPair) oos.readObject();
         oos.close();
         fis.close();
         return kp;
     }

     public static void saveKeyPair(KeyPair kp) throws Exception {

         FileOutputStream fos = new FileOutputStream(RSAKeyStore);
         ObjectOutputStream oos = new ObjectOutputStream(fos);
         // 生成密钥
         oos.writeObject(kp);
         oos.close();
         fos.close();
     }

     /**
      * * 生成公钥 *
      *
      * @param modulus *
      * @param publicExponent *
      * @return RSAPublicKey *
      * @throws Exception
      */
     public static RSAPublicKey generateRSAPublicKey(byte[] modulus,
             byte[] publicExponent) throws Exception {
         KeyFactory keyFac = null;
         try {
             keyFac = KeyFactory.getInstance("RSA",
                     new org.bouncycastle.jce.provider.BouncyCastleProvider());
         } catch (NoSuchAlgorithmException ex) {
             throw new Exception(ex.getMessage());
         }

         RSAPublicKeySpec pubKeySpec = new RSAPublicKeySpec(new BigInteger(
                 modulus), new BigInteger(publicExponent));
         try {
             return (RSAPublicKey) keyFac.generatePublic(pubKeySpec);
         } catch (InvalidKeySpecException ex) {
             throw new Exception(ex.getMessage());
         }
     }

     /**
      * * 生成私钥 *
      *
      * @param modulus *
      * @param privateExponent *
      * @return RSAPrivateKey *
      * @throws Exception
      */
     public static RSAPrivateKey generateRSAPrivateKey(byte[] modulus,
             byte[] privateExponent) throws Exception {
         KeyFactory keyFac = null;
         try {
             keyFac = KeyFactory.getInstance("RSA",
                     new org.bouncycastle.jce.provider.BouncyCastleProvider());
         } catch (NoSuchAlgorithmException ex) {
             throw new Exception(ex.getMessage());
         }

         RSAPrivateKeySpec priKeySpec = new RSAPrivateKeySpec(new BigInteger(
                 modulus), new BigInteger(privateExponent));
         try {
             return (RSAPrivateKey) keyFac.generatePrivate(priKeySpec);
         } catch (InvalidKeySpecException ex) {
             throw new Exception(ex.getMessage());
         }
     }

     /**
      * * 加密 *
      *
      * @param key
      *            加密的密钥 *
      * @param data
      *            待加密的明文数据 *
      * @return 加密后的数据 *
      * @throws Exception
      */
     public static byte[] encrypt(PublicKey pk, byte[] data) throws Exception {
         try {
             Cipher cipher = Cipher.getInstance("RSA",
                     new org.bouncycastle.jce.provider.BouncyCastleProvider());
             cipher.init(Cipher.ENCRYPT_MODE, pk);
             int blockSize = cipher.getBlockSize();// 获得加密块大小，如：加密前数据为128个byte，而key_size=1024
             // 加密块大小为127
             // byte,加密后为128个byte;因此共有2个加密块，第一个127
             // byte第二个为1个byte
             int outputSize = cipher.getOutputSize(data.length);// 获得加密块加密后块大小
             int leavedSize = data.length % blockSize;
             int blocksSize = leavedSize != 0 ? data.length / blockSize + 1
                     : data.length / blockSize;
             byte[] raw = new byte[outputSize * blocksSize];
             int i = 0;
             while (data.length - i * blockSize > 0) {
                 if (data.length - i * blockSize > blockSize)
                     cipher.doFinal(data, i * blockSize, blockSize, raw, i
                             * outputSize);
                 else
                     cipher.doFinal(data, i * blockSize, data.length - i
                             * blockSize, raw, i * outputSize);
                 // 这里面doUpdate方法不可用，查看源代码后发现每次doUpdate后并没有什么实际动作除了把byte[]放到
                 // ByteArrayOutputStream中，而最后doFinal的时候才将所有的byte[]进行加密，可是到了此时加密块大小很可能已经超出了
                 // OutputSize所以只好用dofinal方法。

                 i++;
             }
             return raw;
         } catch (Exception e) {
             throw new Exception(e.getMessage());
         }
     }

     /**
      * * 解密 *
      *
      * @param key
      *            解密的密钥 *
      * @param raw
      *            已经加密的数据 *
      * @return 解密后的明文 *
      * @throws Exception
      */
     public static byte[] decrypt(PrivateKey pk, byte[] raw) throws Exception {
         try {
             Cipher cipher = Cipher.getInstance("RSA",
                     new org.bouncycastle.jce.provider.BouncyCastleProvider());
             cipher.init(cipher.DECRYPT_MODE, pk);
             int blockSize = cipher.getBlockSize();
             ByteArrayOutputStream bout = new ByteArrayOutputStream(64);
             int j = 0;

             while (raw.length - j * blockSize > 0) {
                 bout.write(cipher.doFinal(raw, j * blockSize, blockSize));
                 j++;
             }
             return bout.toByteArray();
         } catch (Exception e) {
             throw new Exception(e.getMessage());
         }
     }

     /**
      * * *
      *
      * @param args *
      * @throws Exception
      */
     public static void main(String[] args) throws Exception {
         RSAPublicKey rsap = (RSAPublicKey) RSAUtil.generateKeyPair().getPublic();
         String test = "hello world";
         byte[] en_test = encrypt(getKeyPair().getPublic(), test.getBytes());
         byte[] de_test = decrypt(getKeyPair().getPrivate(), en_test);
         System.out.println(new String(de_test));
     }
 }

 

LoginAction.java

 package RSA;

 //login
 /*
  * Generated by MyEclipse Struts
  * Template path: templates/java/JavaClass.vtl
  */
 import java.math.BigInteger;
 import java.net.URLDecoder;
 import java.net.URLEncoder;

 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 import RSA.RSAUtil;

 /**
  * MyEclipse Struts Creation date: 06-28-2008
  *
  * XDoclet definition:
  *
  * @struts.action path="/login" name="loginForm" input="/login.jsp"
  *                scope="request" validate="true"
  * @struts.action-forward name="error" path="/error.jsp"
  * @struts.action-forward name="success" path="/success.jsp"
  */
 public class LoginAction {
     /*
      * Generated Methods
      */

     /**
      * Method execute
      *
      * @param mapping
      * @param form
      * @param request
      * @param response
      * @return ActionForward
      */
     public boolean execute(HttpServletRequest request,
             HttpServletResponse response) throws Exception {
         String pwd ;
         String result = request.getParameter("result");
         System.out.println("原文加密后为：");
         System.out.println(result);
         byte[] en_result = new BigInteger(result, 16).toByteArray();
         //System.out.println("转成byte[]" + new String(en_result));
         byte[] de_result = RSAUtil.decrypt(RSAUtil.getKeyPair().getPrivate(),
                 en_result);
         System.out.println("还原密文：");
         System.out.println(new String(de_result));
         StringBuffer sb = new StringBuffer();
         sb.append(new String(de_result));
         pwd = sb.reverse().toString();
         System.out.println(sb);
         System.out.println("=================================");
         pwd = URLDecoder.decode(pwd,"UTF-8");//
         System.out.println(pwd);
         request.setAttribute("pwd", pwd);
         return true;
     }
 }

 

登陆login.jsp

 <%@ page language="java" pageEncoding="UTF-8" contentType="text/html; charset=UTF-8"%>

 >
 <html:html lang="true">
 <head>
     <title>logintitle>

     <script type="text/javascript" src="js/RSA.js">script>
     <script type="text/javascript" src="js/BigInt.js">script>
     <script type="text/javascript" src="js/Barrett.js">script>

     <script type="text/javascript">
 function rsalogin(){
     var thisPwd = document.getElementById("password").value;
     bodyRSA();
     var result = encryptedString(key, encodeURIComponent(thisPwd));
     //alert(encodeURIComponent(thisPwd)+"\r\n"+result);
     loginForm.action="loginCHK.jsp?result="+result;
     loginForm.submit();
 }
 var key ;
 function bodyRSA(){
     setMaxDigits(130);
     key = new RSAKeyPair("10001","","8246a46f44fc4d961e139fd70f4787d272d374532f4d2d9b7cbaad6a15a8c1301319aa6b3f30413b859351c71938aec516fa7147b69168b195e81df46b6bed7950cf3a1c719d42175f73d7c97a85d7d20a9e83688b92f05b3059bb2ff75cd7190a042cd2db97ebc2ab4da366f2a7085556ed613b5a39c9fdd2bb2595d1dc23b5");
 }
 script>
 head>

 <body>
     <form method="post" name="loginForm" target=_blank>
         <table border="0">
             <tr>
                 <td>
                     Password:
                 td>
                 <td>
                     <input type='text' name="password" id=password style='width:400px' value="my passwd"/>
                 td>
             tr>
             <tr>
                 <td colspan="2" align="center">
                     <input type="button" value="SUBMIT" onclick="rsalogin();" />
                 td>
             tr>
         table>
     form>
 body>
 html:html>

 

登陆校验loginCHK.jsp

 <%@ page language="java" pageEncoding="UTF-8" contentType="text/html; charset=UTF-8"%>

 <jsp:directive.page import="RSA.LoginAction"/>

 <%
 LoginAction la = new LoginAction();
 la.execute(request ,response);
 %>
 pwd is [<%=request.getAttribute("pwd")%>]

 

 

================================================

 

另外，通过RSA还可以实现数字签名 ：用私钥签名、公钥验证即可。具体可以看代码：

 package encode;

 import java.security.KeyPair;
 import java.security.KeyPairGenerator;
 import java.security.Signature;

 public class DigitalSignature2Example {
     public static void main(String[] args) {
         args = new String[] { "中国" };

         if (args.length != 1) {
             System.err.println("Usage:java DigitalSignature2Example ");
             System.exit(1);
         }

         try {
             byte[] plainText = args[0].getBytes("UTF-8");
             System.out.println("\nStart generating RSA key.");
             // 生成RSA密钥对
             KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
             // 初始化密钥长度
             keyGen.initialize(1024);
             // 生成密钥对
             KeyPair pair = keyGen.generateKeyPair();
             System.out.println("\nFinish generating RSA key.");
             // 使用私钥签名
             Signature sig = Signature.getInstance("SHA1WithRSA");
             // 用指定的私钥进行初始化
             sig.initSign(pair.getPrivate());
             // 添加要签名的信息
             sig.update(plainText);
             // 返回签名的字节数组
             byte[] signature = sig.sign();
             System.out.println(sig.getProvider().getInfo());
             System.out.println("\nSignature: ");
             System.out.println(new String(signature, "UTF-8"));

             // 使用公钥验证
             System.out.println("\nStart signature verification.");
             sig.initVerify(pair.getPublic());
             // 添加要验证的信息
             sig.update(plainText);
             if (sig.verify(signature)) {
                 System.out.println("Signature verificated.");
             } else {
                 System.out.println("Signature failed.");
             }
         } catch (Exception e) {
             e.printStackTrace();
         }
     }
 }