Getting a SecurityToken from a RequestSecurityTokenResponse in WIF
- by Shawn Cicoria
When you’re working with WIF and WSTrustChannelFactory when you call the Issue operation, you can also request that a RequestSecurityTokenResponse as an out parameter. However, what can you do with that object? Well, you could keep it around and use it for subsequent calls with the extension method CreateChannelWithIssuedToken – or can you? public static T CreateChannelWithIssuedToken<T>(this ChannelFactory<T> factory, SecurityToken issuedToken);
As you can see from the method signature it takes a SecurityToken – but that’s not present on the RequestSecurityTokenResponse class.
However, you can through a little magic get a GenericXmlSecurityToken by means of the following set of extension methods below – just call
rstr.GetSecurityTokenFromResponse() – and you’ll get a GenericXmlSecurityToken as a return.
public static class TokenHelper
{
/// <summary>
/// Takes a RequestSecurityTokenResponse, pulls out the GenericXmlSecurityToken usable for further WS-Trust calls
/// </summary>
/// <param name="rstr"></param>
/// <returns></returns>
public static GenericXmlSecurityToken GetSecurityTokenFromResponse(this RequestSecurityTokenResponse rstr)
{
var lifeTime = rstr.Lifetime;
var appliesTo = rstr.AppliesTo.Uri;
var tokenXml = rstr.GetSerializedTokenFromResponse();
var token = GetTokenFromSerializedToken(tokenXml, appliesTo, lifeTime);
return token;
}
/// <summary>
/// Provides a token as an XML string.
/// </summary>
/// <param name="rstr"></param>
/// <returns></returns>
public static string GetSerializedTokenFromResponse(this RequestSecurityTokenResponse rstr)
{
var serializedRst = new WSFederationSerializer().GetResponseAsString(rstr, new WSTrustSerializationContext());
return serializedRst;
}
/// <summary>
/// Turns the XML representation of the token back into a GenericXmlSecurityToken.
/// </summary>
/// <param name="tokenAsXmlString"></param>
/// <param name="appliesTo"></param>
/// <param name="lifetime"></param>
/// <returns></returns>
public static GenericXmlSecurityToken GetTokenFromSerializedToken(this string tokenAsXmlString, Uri appliesTo, Lifetime lifetime)
{
RequestSecurityTokenResponse rstr2 = new WSFederationSerializer().CreateResponse(
new SignInResponseMessage(appliesTo, tokenAsXmlString),
new WSTrustSerializationContext());
return new GenericXmlSecurityToken(
rstr2.RequestedSecurityToken.SecurityTokenXml,
new BinarySecretSecurityToken(
rstr2.RequestedProofToken.ProtectedKey.GetKeyBytes()),
lifetime.Created.HasValue ? lifetime.Created.Value : DateTime.MinValue,
lifetime.Expires.HasValue ? lifetime.Expires.Value : DateTime.MaxValue,
rstr2.RequestedAttachedReference,
rstr2.RequestedUnattachedReference,
null);
}
}
