This solution is a super super simple bot sample code which is integrated with the OAuth authentication.
Note that, because we want to show you the core logic (the code which shows how to integrate the authentication), this sample doesn't implement the code for real prodction (e.g, security code, exception handling, etc) and uses temporary In-memory data store for bot state store.
Please add these code and implement dedicated custom state store (e.g, state store using Azure Table Storage, CosmosDB, etc) for your production. (Please see the source code comment.)

For this usage, please see my blog post :
https://tsmatz.wordpress.com/2016/09/06/microsoft-bot-framework-bot-with-authentication-and-signin-login/

Thanks,

///// Step for the setup

1.Register your bot (as "Bot Channel Registration") in Azure Bot Service.
  - Set https://{your demo bot}/api/messages as messaging endpoint (webhook url).
  - After you've registered, copy your bot id (bot handle), app id, and app password (secret).

2.Fill your "BotId", "MicrosoftAppId", and "MicrosoftAppPassword" in AuthDemoBot2\Web.config.

3.Login to Azure Portal (https://portal.azure.com/) with Office 365 administrator account. (You need your organization account.)
  Go to Azure Active Directory (Azure AD) management, and register new application.
  - Application type must be "Web app / API"
  - After you've registered, copy application id (client id)
  - Create key (client secret) and copy that value
  - Add "https://{your demo bot}/*" in Reply URLs.
  - Set "Read user mail" (Mail.Read) in "Office 365 Exchange Online" as required permissions
  - Select "Yes" on "Multi-tenanted" setting

5.Fill previous Azure AD app's "ClientId" and "ClientSecret" in AuthDemoWeb\Web.config.

6.Fill https://{your demo bot}/api/callback as "OAuthCallbackUrl" in AuthDemoBot\Web.config.

7.Host AuthDemoBot2 web app (https://{your demo bot}) in public internet. (You can easily publish in Azure App Service with Visual Studio.)