WCF REST basic authentication on certain methods

I have quite a few RESTful (GET and POST) methods implemented in WCF 4.0. All these work over SSL.

An example of some of the methods:

[OperationContract]
[WebInvoke(UriTemplate = "Login?", Method = "POST", ResponseFormat = WebMessageFormat.Json, RequestFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.Bare)]
LoginResponse Login(LoginRequest request);

[OperationContract]
[WebInvoke(UriTemplate = "UpdateDetails?", Method = "POST", ResponseFormat = WebMessageFormat.Json, RequestFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.Bare)]
UpdateUserDetailResponse UpdateDetails(UpdateUserDetailRequest request);

[OperationContract]
[WebInvoke(UriTemplate = "GetDetails?", Method = "POST", ResponseFormat = WebMessageFormat.Json, RequestFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.Bare)]
UserDetailResponse GetDetails(UserDetailRequest request);

I have looked through so many blogs and forums and I still cannot find something that meets my requirements. I need to implement basic authentication on some of the methods but not all. If you look at the examples above I require a username and password to be sent through for the UpdateDetails and GetDetails method, but not for the Login method. The username and password is then authenticated against a database. Is it possible to do something like this?

As a side note: these REST methods are called by many different mobile devices.

I have looked at the following sites and they all implement basic authentication over REST but they cover all the methods mentioned above.

http://msdn.microsoft.com/en-us/library/aa702565.aspx
Adding basic HTTP auth to a WCF REST service
http://custombasicauth.codeplex.com/ (links at the bottom don't work anymore)

Is it possible to do what I want to do?

I created a BasicAuthenticationInvoker class which you attribute on the methods you would like to authenticate as follows:

  [OperationContract]
    [BasicAuthenticationInvoker] // this is the auth attribute!
    [WebInvoke(UriTemplate = "QuickQuote?", Method = "POST", ResponseFormat = WebMessageFormat.Json, RequestFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.Bare)]
    QuickQuoteResponse QuickQuote(QuickQuoteRequest request);

The actual class looks as follows:

 public class BasicAuthenticationInvoker : Attribute, IOperationBehavior, IOperationInvoker
    {
        #region Private Fields

        private IOperationInvoker _invoker;

        #endregion

        #region IOperationBehavior Members

        public void ApplyDispatchBehavior(OperationDescription operationDescription,
                                          DispatchOperation dispatchOperation)
        {
            _invoker = dispatchOperation.Invoker;
            dispatchOperation.Invoker = this;
        }

        public void ApplyClientBehavior(OperationDescription operationDescription,
                                        ClientOperation clientOperation)
        {
        }

        public void AddBindingParameters(OperationDescription operationDescription,
                                         BindingParameterCollection bindingParameters)
        {
        }

        public void Validate(OperationDescription operationDescription)
        {
        }

        #endregion

        #region IOperationInvoker Members

        public object Invoke(object instance, object[] inputs, out object[] outputs)
        {
            if (Authenticate("Client Name here"))
                return _invoker.Invoke(instance, inputs, out outputs);
            else
            {
                outputs = null;
                return null;
            }
        }

        public object[] AllocateInputs()
        {
            return _invoker.AllocateInputs();
        }

        public IAsyncResult InvokeBegin(object instance, object[] inputs,
                                        AsyncCallback callback, object state)
        {
            throw new NotSupportedException();
        }

        public object InvokeEnd(object instance, out object[] outputs, IAsyncResult result)
        {
            throw new NotSupportedException();
        }

        public bool IsSynchronous
        {
            get
            {
                return true;
            }
        }

        #endregion

        private bool Authenticate(string realm)
        {
            string[] credentials = GetCredentials(WebOperationContext.Current.IncomingRequest.Headers);

            if (credentials != null && credentials.Length == 2)
            {
                // do auth here
                var username = credentials[0];
                var password = credentials[1];

               // validate the username and password against whatever auth logic you have

                return true; // if successful
            }

            WebOperationContext.Current.OutgoingResponse.Headers["WWW-Authenticate"] = string.Format("Basic realm=\"{0}\"", realm);
            WebOperationContext.Current.OutgoingResponse.StatusCode = HttpStatusCode.Unauthorized;
            return false;
        }

        private string[] GetCredentials(WebHeaderCollection headers)
        {
            string credentials = WebOperationContext.Current.IncomingRequest.Headers["Authorization"];
            if (credentials != null)
                credentials = credentials.Trim();

            if (!string.IsNullOrEmpty(credentials))
            {
                try
                {
                    string[] credentialParts = credentials.Split(new[] {' '});
                    if (credentialParts.Length == 2 && credentialParts[0].Equals("basic", StringComparison.OrdinalIgnoreCase))
                    {
                        credentials = Encoding.ASCII.GetString(Convert.FromBase64String(credentialParts[1]));
                        credentialParts = credentials.Split(new[] {':'});
                        if (credentialParts.Length == 2)
                            return credentialParts;
                    }
                }
                catch
                {
                }
            }

            return null;
        }
    }