Securing SPAs and Blazor Applications using the BFF (Backend for Frontend) Pattern

Modern web development means that more and more application code is running in the browser. Traditionally this has been JavaScript but more recently there has been the trend to use C#/WASM with Blazor. These modern applications typically also need authentication and single-sign-on as well as token-based security for calling APIs – in other words OpenID Connect and OAuth 2. There are different patterns for securing such applications and this session covers some of the pitfalls of the various approaches, especially given the ever-changing browser landscape. We will conclude with the “backend for frontend” (or BFF) pattern which has become the most secure and stable of these approaches.

0:00 Welcome
5:58 Introduction
9:30 Cookies and CSRF
20:54 Tokens, challenges, XSS
36:00 Browser changes and other problems
53:08 Backend for Frontend Pattern
59:43 Building a BFF with ASP.NET Core
1:11:16 Two types of APIs
1:24:45 Token lifetime management
1:31:40 YARP
1:36:33 Wrapping up

Speaker: Dominick Baier
Dominick spent most of his professional career implementing security systems for his customers and reading protocol specifications. This resulted in a number of popular open-source projects like IdentityServer and IdentityModel. Since 2020 he runs Duende Software Inc together with his longtime friend and colleague Brock Allen. Duende provides a sustainable home for the IdentityServer project and is the one-stop-shop for all things OpenID Connect and OAuth for .NET-based companies.

Twitter: @leastprivilege

Website: https://duendesoftware.com