Java加密技术（九）

  在Java加密技术（八）中，我们模拟了一个基于RSA非对称加密网络的安全通信。现在我们深度了解一下现有的安全网络通信——SSL。 
    我们需要构建一个由CA机构签发的有效证书，这里我们使用上文中生成的自签名证书zlex.cer 
    这里，我们将证书导入到我们的密钥库。 

 keytool -import -alias www.zlex.org -file d:/zlex.cer -keystore d:/zlex.keystore

其中 
-import表示 导入 
-alias指定别名，这里是 www.zlex.org 
-file指定算法，这里是 d:/zlex.cer 
-keystore指定存储位置，这里是 d:/zlex.keystore 
在这里我使用的密码为 654321 

控制台输出： 

 输入keystore密码：
 再次输入新密码:
 所有者:CN=www.zlex.org, OU=zlex, O=zlex, L=BJ, ST=BJ, C=CN
 签发人:CN=www.zlex.org, OU=zlex, O=zlex, L=BJ, ST=BJ, C=CN
 序列号:4a1e48df
 有效期: Thu May 28 16:18:39 CST 2009 至Wed Aug 26 16:18:39 CST 2009
 证书指纹:
          MD5:19:CA:E6:36:E2:DF:AD:96:31:97:2F:A9:AD:FC:37:6A
          SHA1:49:88:30:59:29:45:F1:69:CA:97:A9:6D:8A:CF:08:D2:C3:D5:C0:C4
          签名算法名称:SHA1withRSA
          版本: 3
 信任这个认证？ [否]：  y
 认证已添加至keystore中

OK，最复杂的准备工作已经完成。 
接下来我们将域名 www.zlex.org定位到本机上。打开 C:\Windows\System32\drivers\etc\hosts文件，将 www.zlex.org绑定在本机上。在文件末尾追加 127.0.0.1       www.zlex.org。现在通过地址栏访问 http://www.zlex.org，或者通过 ping命令，如果能够定位到本机，域名映射就搞定了。 
现在，配置tomcat。先将 zlex.keystore拷贝到tomcat的conf目录下，然后配置 server.xml。将如下内容加入配置文件

 <Connector
     SSLEnabled="true"
     URIEncoding="UTF-8"
     clientAuth="false"
     keystoreFile="conf/zlex.keystore"
     keystorePass="123456"
     maxThreads="150"
     port="443"
     protocol="HTTP/1.1"
     scheme="https"
     secure="true"
     sslProtocol="TLS" />

注意 clientAuth="false"测试阶段，置为 false，正式使用时建议使用 true。现在启动tomcat，访问 https://www.zlex.org/。  
显然，证书未能通过认证，这个时候你可以选择安装证书（上文中的 zlex.cer文件就是证书），作为 受信任的根证书颁发机构导入，再次重启浏览器（IE，其他浏览器对于域名www.zlex.org不支持本地方式访问），访问 https://www.zlex.org/，你会看到地址栏中会有个小锁 ，就说明安装成功。所有的浏览器联网操作已经在RSA加密解密系统的保护之下了。但似乎我们感受不到。 
这个时候很多人开始怀疑，如果我们要手工做一个这样的https的访问是不是需要把浏览器的这些个功能都实现呢？不需要！ 

接着上篇内容，给出如下代码实现： 

 import java.io.FileInputStream;
 import java.security.KeyStore;
 import java.security.PrivateKey;
 import java.security.PublicKey;
 import java.security.Signature;
 import java.security.cert.Certificate;
 import java.security.cert.CertificateFactory;
 import java.security.cert.X509Certificate;
 import java.util.Date;

 import javax.crypto.Cipher;
 import javax.net.ssl.HttpsURLConnection;
 import javax.net.ssl.KeyManagerFactory;
 import javax.net.ssl.SSLContext;
 import javax.net.ssl.SSLSocketFactory;
 import javax.net.ssl.TrustManagerFactory;

 /**
  * 证书组件
  *
  * @author 梁栋
  * @version 1.0
  * @since 1.0
  */
 public abstract class CertificateCoder extends Coder {

     /**
      * Java密钥库(Java Key Store，JKS)KEY_STORE
      */
     public static final String KEY_STORE = "JKS";

     public static final String X509 = "X.509";
     public static final String SunX509 = "SunX509";
     public static final String SSL = "SSL";

     /**
      * 由KeyStore获得私钥
      *
      * @param keyStorePath
      * @param alias
      * @param password
      * @return
      * @throws Exception
      */
     private static PrivateKey getPrivateKey(String keyStorePath, String alias,
             String password) throws Exception {
         KeyStore ks = getKeyStore(keyStorePath, password);
         PrivateKey key = (PrivateKey) ks.getKey(alias, password.toCharArray());
         return key;
     }

     /**
      * 由Certificate获得公钥
      *
      * @param certificatePath
      * @return
      * @throws Exception
      */
     private static PublicKey getPublicKey(String certificatePath)
             throws Exception {
         Certificate certificate = getCertificate(certificatePath);
         PublicKey key = certificate.getPublicKey();
         return key;
     }

     /**
      * 获得Certificate
      *
      * @param certificatePath
      * @return
      * @throws Exception
      */
     private static Certificate getCertificate(String certificatePath)
             throws Exception {
         CertificateFactory certificateFactory = CertificateFactory
                 .getInstance(X509);
         FileInputStream in = new FileInputStream(certificatePath);

         Certificate certificate = certificateFactory.generateCertificate(in);
         in.close();

         return certificate;
     }

     /**
      * 获得Certificate
      *
      * @param keyStorePath
      * @param alias
      * @param password
      * @return
      * @throws Exception
      */
     private static Certificate getCertificate(String keyStorePath,
             String alias, String password) throws Exception {
         KeyStore ks = getKeyStore(keyStorePath, password);
         Certificate certificate = ks.getCertificate(alias);

         return certificate;
     }

     /**
      * 获得KeyStore
      *
      * @param keyStorePath
      * @param password
      * @return
      * @throws Exception
      */
     private static KeyStore getKeyStore(String keyStorePath, String password)
             throws Exception {
         FileInputStream is = new FileInputStream(keyStorePath);
         KeyStore ks = KeyStore.getInstance(KEY_STORE);
         ks.load(is, password.toCharArray());
         is.close();
         return ks;
     }

     /**
      * 私钥加密
      *
      * @param data
      * @param keyStorePath
      * @param alias
      * @param password
      * @return
      * @throws Exception
      */
     public static byte[] encryptByPrivateKey(byte[] data, String keyStorePath,
             String alias, String password) throws Exception {
         // 取得私钥
         PrivateKey privateKey = getPrivateKey(keyStorePath, alias, password);

         // 对数据加密
         Cipher cipher = Cipher.getInstance(privateKey.getAlgorithm());
         cipher.init(Cipher.ENCRYPT_MODE, privateKey);

         return cipher.doFinal(data);

     }

     /**
      * 私钥解密
      *
      * @param data
      * @param keyStorePath
      * @param alias
      * @param password
      * @return
      * @throws Exception
      */
     public static byte[] decryptByPrivateKey(byte[] data, String keyStorePath,
             String alias, String password) throws Exception {
         // 取得私钥
         PrivateKey privateKey = getPrivateKey(keyStorePath, alias, password);

         // 对数据加密
         Cipher cipher = Cipher.getInstance(privateKey.getAlgorithm());
         cipher.init(Cipher.DECRYPT_MODE, privateKey);

         return cipher.doFinal(data);

     }

     /**
      * 公钥加密
      *
      * @param data
      * @param certificatePath
      * @return
      * @throws Exception
      */
     public static byte[] encryptByPublicKey(byte[] data, String certificatePath)
             throws Exception {

         // 取得公钥
         PublicKey publicKey = getPublicKey(certificatePath);
         // 对数据加密
         Cipher cipher = Cipher.getInstance(publicKey.getAlgorithm());
         cipher.init(Cipher.ENCRYPT_MODE, publicKey);

         return cipher.doFinal(data);

     }

     /**
      * 公钥解密
      *
      * @param data
      * @param certificatePath
      * @return
      * @throws Exception
      */
     public static byte[] decryptByPublicKey(byte[] data, String certificatePath)
             throws Exception {
         // 取得公钥
         PublicKey publicKey = getPublicKey(certificatePath);

         // 对数据加密
         Cipher cipher = Cipher.getInstance(publicKey.getAlgorithm());
         cipher.init(Cipher.DECRYPT_MODE, publicKey);

         return cipher.doFinal(data);

     }

     /**
      * 验证Certificate
      *
      * @param certificatePath
      * @return
      */
     public static boolean verifyCertificate(String certificatePath) {
         return verifyCertificate(new Date(), certificatePath);
     }

     /**
      * 验证Certificate是否过期或无效
      *
      * @param date
      * @param certificatePath
      * @return
      */
     public static boolean verifyCertificate(Date date, String certificatePath) {
         boolean status = true;
         try {
             // 取得证书
             Certificate certificate = getCertificate(certificatePath);
             // 验证证书是否过期或无效
             status = verifyCertificate(date, certificate);
         } catch (Exception e) {
             status = false;
         }
         return status;
     }

     /**
      * 验证证书是否过期或无效
      *
      * @param date
      * @param certificate
      * @return
      */
     private static boolean verifyCertificate(Date date, Certificate certificate) {
         boolean status = true;
         try {
             X509Certificate x509Certificate = (X509Certificate) certificate;
             x509Certificate.checkValidity(date);
         } catch (Exception e) {
             status = false;
         }
         return status;
     }

     /**
      * 签名
      *
      * @param keyStorePath
      * @param alias
      * @param password
      *
      * @return
      * @throws Exception
      */
     public static String sign(byte[] sign, String keyStorePath, String alias,
             String password) throws Exception {
         // 获得证书
         X509Certificate x509Certificate = (X509Certificate) getCertificate(
                 keyStorePath, alias, password);
         // 获取私钥
         KeyStore ks = getKeyStore(keyStorePath, password);
         // 取得私钥
         PrivateKey privateKey = (PrivateKey) ks.getKey(alias, password
                 .toCharArray());

         // 构建签名
         Signature signature = Signature.getInstance(x509Certificate
                 .getSigAlgName());
         signature.initSign(privateKey);
         signature.update(sign);
         return encryptBASE64(signature.sign());
     }

     /**
      * 验证签名
      *
      * @param data
      * @param sign
      * @param certificatePath
      * @return
      * @throws Exception
      */
     public static boolean verify(byte[] data, String sign,
             String certificatePath) throws Exception {
         // 获得证书
         X509Certificate x509Certificate = (X509Certificate) getCertificate(certificatePath);
         // 获得公钥
         PublicKey publicKey = x509Certificate.getPublicKey();
         // 构建签名
         Signature signature = Signature.getInstance(x509Certificate
                 .getSigAlgName());
         signature.initVerify(publicKey);
         signature.update(data);

         return signature.verify(decryptBASE64(sign));

     }

     /**
      * 验证Certificate
      *
      * @param keyStorePath
      * @param alias
      * @param password
      * @return
      */
     public static boolean verifyCertificate(Date date, String keyStorePath,
             String alias, String password) {
         boolean status = true;
         try {
             Certificate certificate = getCertificate(keyStorePath, alias,
                     password);
             status = verifyCertificate(date, certificate);
         } catch (Exception e) {
             status = false;
         }
         return status;
     }

     /**
      * 验证Certificate
      *
      * @param keyStorePath
      * @param alias
      * @param password
      * @return
      */
     public static boolean verifyCertificate(String keyStorePath, String alias,
             String password) {
         return verifyCertificate(new Date(), keyStorePath, alias, password);
     }

     /**
      * 获得SSLSocektFactory
      *
      * @param password
      *            密码
      * @param keyStorePath
      *            密钥库路径
      *
      * @param trustKeyStorePath
      *            信任库路径
      * @return
      * @throws Exception
      */
     private static SSLSocketFactory getSSLSocketFactory(String password,
             String keyStorePath, String trustKeyStorePath) throws Exception {
         // 初始化密钥库
         KeyManagerFactory keyManagerFactory = KeyManagerFactory
                 .getInstance(SunX509);
         KeyStore keyStore = getKeyStore(keyStorePath, password);
         keyManagerFactory.init(keyStore, password.toCharArray());

         // 初始化信任库
         TrustManagerFactory trustManagerFactory = TrustManagerFactory
                 .getInstance(SunX509);
         KeyStore trustkeyStore = getKeyStore(trustKeyStorePath, password);
         trustManagerFactory.init(trustkeyStore);

         // 初始化SSL上下文
         SSLContext ctx = SSLContext.getInstance(SSL);
         ctx.init(keyManagerFactory.getKeyManagers(), trustManagerFactory
                 .getTrustManagers(), null);
         SSLSocketFactory sf = ctx.getSocketFactory();

         return sf;
     }

     /**
      * 为HttpsURLConnection配置SSLSocketFactory
      *
      * @param conn
      *            HttpsURLConnection
      * @param password
      *            密码
      * @param keyStorePath
      *            密钥库路径
      *
      * @param trustKeyStorePath
      *            信任库路径
      * @throws Exception
      */
     public static void configSSLSocketFactory(HttpsURLConnection conn,
             String password, String keyStorePath, String trustKeyStorePath)
             throws Exception {
         conn.setSSLSocketFactory(getSSLSocketFactory(password, keyStorePath,
                 trustKeyStorePath));
     }
 }

增加了 configSSLSocketFactory方法供外界调用，该方法为HttpsURLConnection配置了SSLSocketFactory。当HttpsURLConnection配置了SSLSocketFactory后，我们就可以通过HttpsURLConnection的getInputStream、getOutputStream，像往常使用HttpURLConnection做操作了。尤其要说明一点，未配置SSLSocketFactory前，HttpsURLConnection的getContentLength()获得值永远都是 -1。 

给出相应测试类： 

 import static org.junit.Assert.*;

 import java.io.DataInputStream;
 import java.io.InputStream;
 import java.net.URL;

 import javax.net.ssl.HttpsURLConnection;

 import org.junit.Test;

 /**
  *
  * @author 梁栋
  * @version 1.0
  * @since 1.0
  */
 public class CertificateCoderTest {
     private String password = "123456";
     private String alias = "www.zlex.org";
     private String certificatePath = "d:/zlex.cer";
     private String keyStorePath = "d:/zlex.keystore";
     private String clientKeyStorePath = "d:/zlex-client.keystore";
     private String clientPassword = "654321";

     @Test
     public void test() throws Exception {
         System.err.println("公钥加密——私钥解密");
         String inputStr = "Ceritifcate";
         byte[] data = inputStr.getBytes();

         byte[] encrypt = CertificateCoder.encryptByPublicKey(data,
                 certificatePath);

         byte[] decrypt = CertificateCoder.decryptByPrivateKey(encrypt,
                 keyStorePath, alias, password);
         String outputStr = new String(decrypt);

         System.err.println("加密前: " + inputStr + "\n\r" + "解密后: " + outputStr);

         // 验证数据一致
         assertArrayEquals(data, decrypt);

         // 验证证书有效
         assertTrue(CertificateCoder.verifyCertificate(certificatePath));

     }

     @Test
     public void testSign() throws Exception {
         System.err.println("私钥加密——公钥解密");

         String inputStr = "sign";
         byte[] data = inputStr.getBytes();

         byte[] encodedData = CertificateCoder.encryptByPrivateKey(data,
                 keyStorePath, alias, password);

         byte[] decodedData = CertificateCoder.decryptByPublicKey(encodedData,
                 certificatePath);

         String outputStr = new String(decodedData);
         System.err.println("加密前: " + inputStr + "\n\r" + "解密后: " + outputStr);
         assertEquals(inputStr, outputStr);

         System.err.println("私钥签名——公钥验证签名");
         // 产生签名
         String sign = CertificateCoder.sign(encodedData, keyStorePath, alias,
                 password);
         System.err.println("签名:\r" + sign);

         // 验证签名
         boolean status = CertificateCoder.verify(encodedData, sign,
                 certificatePath);
         System.err.println("状态:\r" + status);
         assertTrue(status);

     }

     @Test
     public void testHttps() throws Exception {
         URL url = new URL("https://www.zlex.org/examples/");
         HttpsURLConnection conn = (HttpsURLConnection) url.openConnection();

         conn.setDoInput(true);
         conn.setDoOutput(true);

         CertificateCoder.configSSLSocketFactory(conn, clientPassword,
                 clientKeyStorePath, clientKeyStorePath);

         InputStream is = conn.getInputStream();

         int length = conn.getContentLength();

         DataInputStream dis = new DataInputStream(is);
         byte[] data = new byte[length];
         dis.readFully(data);

         dis.close();
         System.err.println(new String(data));
         conn.disconnect();
     }
 }

注意 testHttps方法，几乎和我们往常做HTTP访问没有差别，我们来看控制台输出： 

 "-//W3C//DTD HTML 4.0 Transitional//EN">
 Apache Tomcat Examples
 "text/html">



 Apache Tomcat Examples

    
     "servlets">Servlets examples   
     "jsp">JSP Examples

通过浏览器直接访问 https://www.zlex.org/examples/你也会获得上述内容。也就是说应用甲方作为服务器构建tomcat服务，乙方可以通过上述方式访问甲方受保护的SSL应用，并且不需要考虑具体的加密解密问题。甲乙双方可以经过相应配置，通过双方的tomcat配置有效的SSL服务，简化上述代码实现，完全通过证书配置完成SSL双向认证！