Axis 运行时动态选择 证书（select a certifiate at runtime）

 

目 錄

1. The Motivation
2. The Problem
3. The Solution
4. Usage / Configuration
5. Getting the code
6. Shortcomings
7. Comments, Feedback, Support

 

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The following describes a setup for dynamically choosing the client certificate used for SSL Authentication from an Axis Client.

This method has been tested using Axis 1.4 and Java 1.5 under Tomcat 5.5.20 and WebSphere 6.1.

 

The Motivation

Generally, a client will use one client certificate to identify itself to services it is accessing. Depending on the application, the client certificate will belong to the user of the application, or will be part of the installation of the application client itself.

Sometimes this model is insufficient:

• Perhaps more than one service needs to be accessed by the client, and the client is not free to choose the certificates used for access. In this case the client will need to work with the (multiple) certificates provided.
• In some cases the client will be acting "on behalf" of more than one user, and will want to employ the different user's different certificates to authenticate against backend systems.

Whatever the reason, sometimes the "one client, one certificate" model is not applicable. In this case, the client has to work, dynamically at run-time, with more than one certificate at a time.

 

The Problem

In its current implementation, the SSL Transport for Axis has several shortcomings:

• The base SecureSocketFactory (JSSE!SocketFactory) cannot be configured dynamically. It is configured using environment variables, which is not suitable if it is desired to change the client certificate at run-time.

• The SunJSSE!SocketFactory is more configurable, accepting a keyfile parameter from the Axis configuration at run-time. This is the one to use, however, by itself it does not do all that we need, so we have provided an extension of this class (see below)...

• Even the SunJSSE!SocketFactory does not accept all the configurations we need (eg: truststore config)

• Even were the SocketFactory fully configurable to our desires, dynamic configuration at runtime would not be possible. This is beacause Axis caches the instantiated SocketFactories, meaning settings are applied only once.

• The cacheing of SocketFactories occurs in a component called SocketFactoryFactory, the cache remembers one entry per protocol. So, the moment you make the first call over https, a SocketFactory is created for the protocol https using the currently configured parameters. After this no new SocketFactories are created for https, even if the parameters (eg keystore name) change.

So, it seems we are in a bind if we want to enable dynamic runtime selection of the client certificate.

 

The Solution

The solution depends on a few modified classes for Apache Axis. In particular the solution consists of:

• A modified SocketFactoryFactory, which implements a cacheing scheme in which the keystore name is considered

• An extension to SunJSSE!SocketFactory which allows more configuration from Axis

• An Axis EngineConfiguration class, SSL!ClientAxisConfig, which holds the SSL paramters, and sets everything up

Together, use of these components allows the desired dynamic configuration.

 

Usage / Configuration

To set up dynamic certificates for your axis client, proceed as follows:

1. Replace the SocketFactoryFactory class with your new version. This can be done in one of three ways (method 1 is safest):

   1. Find the original class file within axis.jar (it lives in org/apache/axis/components/net) and delete it, replace it with the modified class file
   2. Place the modified class file in a new JAR, and make sure this JAR loads before axis.jar (eg call it _axis.jar)
   3. For webapps, place the modified class file within your WEB-INF/classes folder. It seems tomcat loads these before axis.jar
2. Add the remaining classes to your application

3. Use the SSL!ClientAxisConfig class to initialize your Axis client before making a call (see example below)

4. When you want to use a different certificate, create a new SSL!ClientAxisConfig, with updated paramters, and use it to create a new Axis client. This client will use the new certificate.

Example usage of the SSL!ClientAxisConfig:

切換行號

   1 // create config
   2 boolean logging = false; // no logging
   3 SSLClientAxisEngineConfig axisConfig = new SSLClientAxisEngineConfig();
   4 axisConfig.setKeystore("/path/to/clientkey.p12");
   5 axisConfig.setKeystoreType("PKCS12");
   6 axisConfig.setKeystorePassword("changeit");
   7 axisConfig.setTruststore("/path/to/truststore.jks");
   8 axisConfig.setTruststoreType("JKS");
   9 axisConfig.setTruststorePassword("changeit");
  10 if (logging)
  11     axisConfig.setDebugBaseDir("/path/to/logs");
  12 axisConfig.initialize(logging);
  13 // initialize service
  14 URL soapURL = new URL("https://myserver.com/myapp/services/mywebserviceport");
  15 MyWebServiceServiceLocator locator = new MyServiceLocator(axisConfig);
  16 MyWebServicePort port = locator.getMyWebServicePort(soapURL);
  17 MyWebServiceBindingStub stub = (MyWebServiceBindingStub) port;
  18 // make a call to the webservice (assume no params for this operation)
  19 MyResultType result = stub.myoperation1();

Note: In the example above it is assumed that you have created the client stubs for the web service "MyWebService" using the Axis WSD!L2Java tool.

Note: For an explanation of the logging features, please see FrontPage/Axis/Logging/Logging_with_SSL and FrontPage/Axis/Logging/In_Memory_Logging

Should you have questions about the code, please feel free to contact me (the Author) at: runger --AT-- aon.at