Auth0 VSTO Excel 2016 Add-in

This sample demonstrates how to build a VSTO Excel 2016 add-in (C#). This sample creates a Ribbon with a single button. When the user clicks the button a web browser will open redirecting the user the /authiorize endpoint. Once the user completes login the code and code verifier will be returned and exchanged for tokens. This sample uses Auth0 as an authentication and authorization server using Authorization Code Grant Flow with PKCE.

A special note about Excel. If you are migrating from the legacy (deprecated) SDK Auth0.WinformsOrWPF there is a significant breaking change. In Excel the System.Threading.SynchronizationContext.Current is set to null. With the old SDK this was not problematic. However, in the new SDK Auth0.OidcClient.WinForms takes on a dependency to IdentityModel.OidcClient2. This SDK does a lot asynchronous calls with await/async and utilizes ConfigureAwait(false). At some point the SDK makes a call to System.Net.Http.HttpClient.GetUrl(string). This class is thread safe and when used will run on a new thread in a mutli-tenant apartment. After the call is made .NET will look to see if the SynchronizationContext is not null and use that for swithing the current thread. If .NET finds this as null it falls back to using the ThreadScheduler. In the case of ThreadScheduler the remaining method calls will continue on the MTA thread. Eventually the method attempts to invoke the WebBrowser object and this fails, because it requies to be invoked in a single-threaded apartment. The following example solves this by setting up a SynchronizationContext before invoking login.

Setup

Prerequisites

The following tools are required to build and run this sample.

1. Excel 2016
2. Visual Studio 2016 Community Edition or better
3. VSTO Visual Studio Tools
4. .NET 4.6.1

Setting You Tenant

After you have a working development environment you must setup your Auth0 tenant. We will need to setup a new client with appropriate settings.

1. Open manage and go to Clients
2. Click on the CREATE CLIENT button.
3. Give the client a name, select Native application, and click CREATE
4. Add https:{your-tenant}.auth0.com/mobile to the Allowed Callback URLs
5. At the bottom click on the Show Advanced Settings url and the click on the OAuth link.
6. Ensure OIDC Conformant option is selected
7. Ensure the JsonWebToken Signature Algorithm is RS256

Configuring the Application

Setting up the add-in is very simple. Now that you have created a new client you will need two things, the client_id and the auth0 domain (e.g. your-tenant.auth0.com). After you have these you can copy them into the app.config of Auth0.ExcelAddin.

<add key="Auth0ClientId" value="{your-client-id}"/>
<add key="Auth0Domain" value="{your-auth0-domain}"/>

After upating these settings hit F5 and you are ready to go. By default the login burtton will be in the Add-in ribbon. Click the login button and a new window will open redirect the user to the /authorize endpoint to begin authentication.

Doing More With The Extension

This extension simply does a standard authentication. You can incorporate and audience for authorization, do single sign on, or more by updating the action in the button action for the btnLogin.

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What is Auth0?

Auth0 helps you to:

• Add authentication with multiple authentication sources, either social like Google, Facebook, Microsoft Account, LinkedIn, GitHub, Twitter, Box, Salesforce, amont others, or enterprise identity systems like Windows Azure AD, Google Apps, Active Directory, ADFS or any SAML Identity Provider.
• Add authentication through more traditional username/password databases.
• Add support for linking different user accounts with the same user.
• Support for generating signed Json Web Tokens to call your APIs and flow the user identity securely.
• Analytics of how, when and where users are logging in.
• Pull data from other sources and add it to the user profile, through JavaScript rules.

Create a free account in Auth0

1. Go to Auth0 and click Sign Up.
2. Use Google, GitHub or Microsoft Account to login.

Issue Reporting

If you have found a bug or if you have a feature request, please report them at this repository issues section. Please do not report security vulnerabilities on the public GitHub issue tracker. The Responsible Disclosure Program details the procedure for disclosing security issues.

Author

Auth0

License

This project is licensed under the MIT license. See the LICENSE file for more info.