Time stamp

A time stamp is the value of an object that indicates the system time at some critical point in the history of the object.

A time stamp is included in a message to reduce the vulnerability of an application to replay attacks. In web services, a replay attack occurs when an HTTP request is intercepted and the content is resent to the provider in its original form.

When we include a time stamp in a message, we must protect its integrity using transport security, such as secure sockets layer (SSL) or message-level security, such as XML digital signature. If we do not protect the integrity of the time stamp, it is possible to capture the message and retransmit the content with a different time stamp, message expiration date, or both.

For both the JAX-RPC and JAX-WS WS-Security run times, 5 minutes is the default message expiration time used for the receiver if a value is not specified in the message. If a different expiration is required for a specific client or we are unsure of the target service default value, configure a message expiration time value for the outbound time stamp.

• When the Web Services Security JAX-RPC and JAX-WS run times generate or consume a message, they do not enforce that the integrity of the time stamp is protected.

• The Web Services Security JAX-RPC and JAX-WS run times do not have a default outbound message expiration value. To include a message expiration value in a message, configure it. Although the JAX-WS run time does not have a default outbound message expiration value, we can configure an outbound message expiration value in the default general bindings. This value is acquired by all applications at the level for which the default bindings apply. For example, the value might be acquired at the cell or application level.

• For the JAX-RPC run time, the time stamp expiration value is specified in the web services deployment descriptor extension. We cannot modify the web services deployment descriptor extension from the administrative console; we can only view it. To modify the deployment descriptor extension, we must use an assembly tool and add or change the time stamp expiration value for a JAX-RPC application.

• If WS-Security constraints exist to consume a timestamp, the client must send a timestamp.
• WebSphere Application Server enforces IncludeTimestamp policy assertion. However, many service providers require that <wsu:Timestamp> element in the request, but do not send one in the response. There could also be no Security header in the response at all, much less a timestamp. The following error will occur on a client when IncludeTimestamp is in the policy but no timestamp is returned in the response:

  CWWSS5730E: A required timestamp is not found.
  

  To resolve the issue, either configure the service provider to send a timestamp or configure the client to not require the timestamp by setting the com.ibm.wsspi.wssecurity.consumer.timestampRequired custom property to false in the WS-Security policy bindings. See Web services security custom properties for more information.

The JAX-WS WS-Security runtime complies with the OASIS WS-SecurityPolicy 1.2 specification Timestamp Required requirement. To configure an application to not require an inbound time stamp when an outbound time stamp is configured we can add the com.ibm.wsspi.wssecurity.consumer.timestampRequired custom property as either an inbound or an inbound/outbound web services security custom property.

The JAX-WS runtime always puts the timestamp first, but the JAX-RPC runtime does not. If we are using the JAX-RPC WS-Security 1.0 runtime, and want to emit the Timestamp first in the Security header, we must:

• Set the property com.ibm.wsspi.wssecurity.timestamp.keyword to SecurityFirst.

• Set the property com.ibm.wsspi.wssecurity.timestamp.dialect to http://www.ibm.com/websphere/webservices/wssecurity/dialect-was. The default value for com.ibm.wsspi.wssecurity.timestamp.dialect is dialect-was, but for the desired function to work, the property must be set explicitly.

These properties are set as properties on the Timestamp generator in the Web services deployment descriptor extension. Because it is in the extension, it can only be edited with an Assembly Tool.

Related:

Web Services Security enhancements

Configure the WS-Security policy

Message expiration settings

Default bindings and runtime properties for Web Services Security

Web Services Security property configuration settings