java客戶端代碼實現
在Java中要訪問Https鏈接時,會用到一個關鍵類HttpsURLConnection;參見如下實現代碼:
// 創建URL對象 URL myURL = new URL("https://www.sun.com"); // 創建HttpsURLConnection對象,並設置其SSLSocketFactory對象 HttpsURLConnection httpsConn = (HttpsURLConnection) myURL.openConnection(); // 取得該連接的輸入流,以讀取響應內容 InputStreamReader insr = new InputStreamReader(httpsConn.getInputStream()); // 讀取服務器的響應內容並顯示 int respInt = insr.read(); while (respInt != -1) { System.out.print((char) respInt); respInt = insr.read(); }
在取得connection的時候和正常瀏覽器訪問一樣,仍然會驗證服務端的證書是否被信任(權威機構發行或者被權威機構簽名);如果服務端證書不被信任,則默認的實現就會有問題,一般來說,用SunJSSE會拋如下異常信息:
javax.net.ssl.SSLHandshakeException:
sun.security.validator.ValidatorException: PKIX path building |
failed:
sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target |
上面提到SunJSSE,JSSE(Java Secure Socket Extension)是實現Internet安全通信的一系列包的集合。它是一個SSL和TLS的純Java實現,可以透明地提供數據加密、服務器認證、信息完整性等功能,可以使我們像使用普通的套接字一樣使用JSSE建立的安全套接字。JSSE是一個開放的標準,不只是Sun公司才能實現一個SunJSSE,事實上其他公司有自己實現的JSSE,然後通過JCA就可以在JVM中使用。
關於JSSE的詳細信息參考官網Reference:http://java.sun.com/j2se/1.5.0/docs/guide/security/jsse/JSSERefGuide.html;
以及Java Security Guide:http://java.sun.com/j2se/1.5.0/docs/guide/security/;
在深入瞭解JSSE之前,需要了解一個有關Java安全的概念:客戶端的TrustStore文件。客戶端的TrustStore文件中保存着被客戶端所信任的服務器的證書信息。客戶端在進行SSL連接時,JSSE將根據這個文件中的證書決定是否信任服務器端的證書。在SunJSSE中,有一個信任管理器類負責決定是否信任遠端的證書,這個類有如下的處理規則:
1)若系統屬性javax.net.sll.trustStore指定了TrustStore文件,那麼信任管理器就去jre安裝路徑下的lib/security/目錄中尋找並使用這個文件來檢查證書。
2)若該系統屬性沒有指定TrustStore文件,它就會去jre安裝路徑下尋找默認的TrustStore文件,這個文件的相對路徑爲:lib/security/jssecacerts。
3)若jssecacerts不存在,但是cacerts存在(它隨J2SDK一起發行,含有數量有限的可信任的基本證書),那麼這個默認的TrustStore文件就是lib/security/cacerts。
那遇到這種情況,怎麼處理呢?有以下兩種方案:
1)按照以上信任管理器的規則,將服務端的公鑰導入到jssecacerts,或者是在系統屬性中設置要加載的trustStore文件的路徑;證書導入可以用如下命令:keytool -import -file src_cer_file –keystore dest_cer_store;至於證書可以通過瀏覽器導出獲得;
2)、實現自己的證書信任管理器類,比如MyX509TrustManager,該類必須實現X509TrustManager接口中的三個method;然後在HttpsURLConnection中加載自定義的類,可以參見如下兩個代碼片段,其一爲自定義證書信任管理器,其二爲connect時的代碼:
package test; import java.io.FileInputStream; import java.security.KeyStore; import java.security.cert.CertificateException; import java.security.cert.X509Certificate; import javax.net.ssl.TrustManager; import javax.net.ssl.TrustManagerFactory; import javax.net.ssl.X509TrustManager; public class MyX509TrustManager implements X509TrustManager { /* * The default X509TrustManager returned by SunX509. We'll delegate * decisions to it, and fall back to the logic in this class if the * default X509TrustManager doesn't trust it. */ X509TrustManager sunJSSEX509TrustManager; MyX509TrustManager() throws Exception { // create a "default" JSSE X509TrustManager. KeyStore ks = KeyStore.getInstance("JKS"); ks.load(new FileInputStream("trustedCerts"), "passphrase".toCharArray()); TrustManagerFactory tmf = TrustManagerFactory.getInstance("SunX509", "SunJSSE"); tmf.init(ks); TrustManager tms [] = tmf.getTrustManagers(); /* * Iterate over the returned trustmanagers, look * for an instance of X509TrustManager. If found, * use that as our "default" trust manager. */ for (int i = 0; i < tms.length; i++) { if (tms[i] instanceof X509TrustManager) { sunJSSEX509TrustManager = (X509TrustManager) tms[i]; return; } } /* * Find some other way to initialize, or else we have to fail the * constructor. */ throw new Exception("Couldn't initialize"); } /* * Delegate to the default trust manager. */ public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException { try { sunJSSEX509TrustManager.checkClientTrusted(chain, authType); } catch (CertificateException excep) { // do any special handling here, or rethrow exception. } } /* * Delegate to the default trust manager. */ public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException { try { sunJSSEX509TrustManager.checkServerTrusted(chain, authType); } catch (CertificateException excep) { /* * Possibly pop up a dialog box asking whether to trust the * cert chain. */ } } /* * Merely pass this through. */ public X509Certificate[] getAcceptedIssuers() { return sunJSSEX509TrustManager.getAcceptedIssuers(); } } // 創建SSLContext對象,並使用我們指定的信任管理器初始化 TrustManager[] tm = { new MyX509TrustManager() }; SSLContext sslContext = SSLContext.getInstance("SSL", "SunJSSE"); sslContext.init(null, tm, new java.security.SecureRandom()); // 從上述SSLContext對象中得到SSLSocketFactory對象 SSLSocketFactory ssf = sslContext.getSocketFactory(); // 創建URL對象 URL myURL = new URL("https://ebanks.gdb.com.cn/sperbank/perbankLogin.jsp"); // 創建HttpsURLConnection對象,並設置其SSLSocketFactory對象 HttpsURLConnection httpsConn = (HttpsURLConnection) myURL.openConnection(); httpsConn.setSSLSocketFactory(ssf); // 取得該連接的輸入流,以讀取響應內容 InputStreamReader insr = new InputStreamReader(httpsConn.getInputStream()); // 讀取服務器的響應內容並顯示 int respInt = insr.read(); while (respInt != -1) { System.out.print((char) respInt); respInt = insr.read(); }
對於以上兩種實現方式,各有各的優點,第一種方式不會破壞JSSE的安全性,但是要手工導入證書,如果服務器很多,那每臺服務器的JRE都必須做相同的操作;第二種方式靈活性更高,但是要小心實現,否則可能會留下安全隱患;