private SecurityPolicyAssertion
GetSecurityPolicyAssertionForHokToken(XmlElement xmlToken)
{
    //When this property is set to true, client requests that use the POST method
    //expect to receive a 100-Continue response from the server to indicate that
    //the client should send the data to be posted. This mechanism allows clients
    //to avoid sending large amounts of data over the network when the server,
    //based on the request headers, intends to reject the request
    ServicePointManager.Expect100Continue = true;
    ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;

    X509Certificate2 certificateToBeAdded = new X509Certificate2();
    string certificateFile = ConfigurationManager.AppSettings["PfxCertificateFile"];
    string password = ConfigurationManager.AppSettings["PfxCertificateFilePassword"];
    certificateToBeAdded.Import(certificateFile,
                                password ?? string.Empty,
                                X509KeyStorageFlags.MachineKeySet);

    var customSecurityAssertion = new CustomSecurityAssertionHok();
    customSecurityAssertion.BinaryToken = xmlToken;
    customSecurityAssertion.TokenType = strSamlV2TokenType;
    customSecurityAssertion.SecurityToken = new X509SecurityToken(certificateToBeAdded);

    return customSecurityAssertion;
}