IBM Support

Trust authentication interceptor



The IWS server has been enhanced in the area of authentication by allowing for the definition of a user-defined authentication mechanism called the trust association interceptor (TAI).


What is it?

When a web service is protected using basic authentication, but selected requests do not present the required credential, a trust authentication interceptor (TAI) can be developed, configured, and deployed in the server to allow selected "unauthenticated" requests to be processed.
For example, where an API gateway component has already authenticated requests that presented a credential, and no associated credential is available for the onward request to the server, a TAI can be developed to identify such requests and allow them to be processed under a fixed application or task identity. Requests that do not match the criteria of the TAI must still present the required credential to proceed. The criteria by which a TAI decides to block or allow a request is entirely due to the design of the TAI implementation.

The web administration GUI has been enhanced to show the following panel for configuring a TAI:
image 7712
  • Interceptor class name. In order to configure a TAI, you need specify a fully qualified package name of the interceptor class.  
  • Invoke TAI for unprotected applications.  Whether the TAI should be invoked for all web services or just for protected web services.  
  • Allow fallback to application authentication. Whether to fall back to application authentication (assuming it is protected) if the TAI fails to authenticate.
  • Libraries for interceptor. The JAR file that contains the TAI, in addition to any additional libraries that the TAI is depends on.
  • Interceptor properties.  Properties that are to be passed to the TAI.
Changes to the user TAI configuration require the server to be in a stopped state.

Here is a sample TAI class called SimpleTAI, which also lists all available methods from the TrustAssociationInterceptor interface:

import java.util.Properties;

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


public class SimpleTAI implements TrustAssociationInterceptor 
   public SimpleTAI()

   public boolean isTargetInterceptor(HttpServletRequest req)
                  throws WebTrustAssociationException 
      //Add logic to determine whether to intercept this request
      return true;

   public TAIResult negotiateValidateandEstablishTrust(HttpServletRequest req,
                    HttpServletResponse resp) throws WebTrustAssociationFailedException 
        // Add logic to authenticate a request and return a TAI result.
        String tai_user = "taiUser";
        return TAIResult.create(HttpServletResponse.SC_OK, tai_user);

   public int initialize(Properties arg0) throws WebTrustAssociationFailedException 
        return 0;

   public String getVersion() 
        return "1.0";

   public String getType() 
        return this.getClass().getName();

   public void cleanup() { }
When processing the web request, the server calls out and passes the HttpServletRequest and HttpServletResponse to the trust association interceptor. The HttpServletRequest calls the isTargetInterceptor method of the interceptor to see whether the interceptor can process the request. After a trust association interceptor is selected, the HttpServletRequest is processed by the negotiateValidateandEstablishTrust method of the interceptor, and the result is returned in a TAIResult object. You can add your own logic code to each method of the custom TAI class.
To compile the code, you need the following (xx is some number):
  • /QIBM/ProdData/OS/ApplicationServer/runtime/wlp/dev/api/ibm/
  • /QIBM/ProdData/OS/ApplicationServer/runtime/wlp/dev/api/ibm/
See also the Java API document for the TAI interface. The Java API documentation for each Liberty API is detailed in the Programming interfaces (Javadoc) section of the online IBM Knowledge Center.  (See Programming interfaces -> Liberty API -> WebSphere Security API, package

Why use it?

To authenticate users using third-party security services.


The support is enabled in the following HTTP group PTFs and PTFs:

V7R2M0  SF99713 Level 40, SI75444,SI75178
V7R3M0  SF99722 Level 28, SI75443,SI75177
V7R4M0  SF99662 Level 09, SI75442,SI75176

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Document Information

Modified date:
26 February 2021