In the previous chapters, we saw how to exchange data between multiple services using an event bus and resilient clients and how to consume messages and run background services using ASP.NET Core. This chapter is about securing service data. It covers concepts such as SSL, cross-origin resource sharing (CORS), and HTTP/2, and it walks through the implementation of token-based authentication. 

In more detail, this chapter covers the following topics:

• A general overview of SSL
• How to enable CORS in an ASP.NET Core service
• How to enable HTTPS and HTTP/2
• How token-based authentication works
• How to build token-based authentication in ASP.NET Core

By the end of the chapter, you will have a broad understanding of the security features provided by ASP.NET Core, and you will be able to implement token-based authentication in ASP.NET Core.