FederatedAuthentication

Global.asax.cs

protected void Application_Start()
{
    ...
    FederatedAuthentication.ServiceConfigurationCreated += OnServiceConfigurationCreated;
}

private void OnServiceConfigurationCreated(object sender, ServiceConfigurationCreatedEventArgs e)
{
    var sessionTransforms = new List<CookieTransform>(new CookieTransform[]
        {
            new DeflateCookieTransform(),
            new RsaEncryptionCookieTransform(e.ServiceConfiguration.ServiceCertificate),
            new RsaSignatureCookieTransform(e.ServiceConfiguration.ServiceCertificate)
        });

    var sessionHandler = new SessionSecurityTokenHandler(sessionTransforms.AsReadOnly());
    e.ServiceConfiguration.SecurityTokenHandlers.AddOrReplace(sessionHandler);
}