java - 为什么 SSL 的性能在 java 中的循环值中不同

Question

我想计算 ssl(客户端)与服务器建立连接并进行握手所需的时间。这是我的代码，它工作正常。

private boolean SslTlsConnection() throws IOException, NoSuchAlgorithmException, KeyStoreException, CertificateException, UnrecoverableKeyException, KeyManagementException {

        KeyStore client = KeyStore.getInstance("JKS");
        client.load(new FileInputStream(currentPath + "clientcert.keystore"), Password.toCharArray());

        KeyStore trust = KeyStore.getInstance("JKS");
        trust.load(new FileInputStream(currentPath + "myTrustStore.keystore"), Password.toCharArray());

        KeyManagerFactory kmf = KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm());
        kmf.init(client, Password.toCharArray());

        TrustManagerFactory tmf = TrustManagerFactory.getInstance("X509");
        tmf.init(trust);

        SSLContext sc = SSLContext.getInstance("SSL");
        TrustManager[] trustManagers = tmf.getTrustManagers();
        sc.init(kmf.getKeyManagers(), trustManagers, new java.security.SecureRandom());

        SSLSocketFactory ssf = sc.getSocketFactory();
        sslsocket = (SSLSocket) ssf.createSocket(Properties.host, Properties.portNumber);

        sslsocket.startHandshake();
        System.out.println("Handshaking Complete");
        System.out.println("Just connected to " + sslsocket.getInetAddress() + "\n");

        transport = new IOTransport(sslsocket);
        return false;
}


private void close(){
 sslsocket.close();
}

我只是对性能感到好奇。我在一个循环中运行多个连接，我正在计算 ssl 需要进行握手的时间。我的问题是，与其他客户端相比，为什么客户端第一次连接 ssl 需要花费如此长的时间。我做错了什么吗？

for (int i = 1; i < loopvalue; i++) {
   long elapseTime = System.currentTimeMillis();
   SslTlsConnection()
   long elapseTime = (System.currentTimeMillis() - elapseTime);
   close();
}

我已经尝试过测试。这是结果

SSL_Execution_Time
First Execution Time 453ms
Second Execution Time 85ms
Third Execution Time 90ms

Answer 1

最初的 ssl 握手只发生一次。客户端和服务器就协议(protocol)(ssl vs tls)和密码达成一致，然后他们交换 key 。因此，在初始握手时会受到打击。之后唯一发生的事情就是使用已经交换的 key 进行加密和解密。

http://www.ibm.com/support/knowledgecenter/SSFKSJ_7.1.0/com.ibm.mq.doc/sy10660_.htm