Hi Jacques,

Your assertion must run after the WSE security assertion in order to obtain
the identity token. Did you try with the property
SoapContext.Current.IdentityToken ?.
If that approach does not work, you should try with a custom security
assertion. (Deriving your class from one of the existing turn-key
assertions).

Something like this:

public class MyUsernameForCertificateSecurityAssertion :
UsernameForCertificateAssertion
   {
       public MyUsernameForCertificateSecurityAssertion ()
           : base()
       {
           // empty
       }

       public override SoapFilter
CreateClientOutputFilter(FilterCreationContext context)
       {
           return new MyClientOutputFilter(this);
       }

rotected class MyClientOutputFilter :
UsernameForCertificateAssertion.ClientOutputFilter
       {
           EndpointProtectionRequirements endpointProtectionRequirements;

           public
BodyProtectionClientOutputFilter(UsernameForCertificateAssertion assertion)
               : base(assertion)
           {
           }

           public override void SecureMessage(SoapEnvelope envelope,
Microsoft.Web.Services3.Security.Security security,
MessageProtectionRequirements request)
           {
               base.SecureMessage(envelope, security, request);

               SecurityToken token = envelope.Context.IdentityToken;
           }
       }

Regards,
Pablo Cibraro
http://weblogs.asp.net/cibrax