Tutorials ASP.NET Core Web API Tutorial
HMAC Authentication in ASP.NET Core Web API — Complete Guide
HMAC Authentication in ASP.NET Core Web API — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of ASP.NET Core Web API Tutorial on Toolliyo Academy.
On this page
ASP.NET Core Web API Tutorial · Lesson 134 of 175
HMAC Authentication in ASP.NET Core Web API
Beginner ✓ → Intermediate ✓ → Advanced → Professional
Advanced · 3 — Security & patterns · ~10 min · Module 13: Security
What is this?
HMAC signs requests with a shared secret — client and server compute a hash of method, URL, body, and timestamp.
Why should you care?
Webhook providers (payment gateways, shipping) use HMAC to prove the request was not tampered with.
See it live — copy this example
Create a Web API (dotnet new webapi), paste the example, run dotnet run, test in Swagger.
// Verify X-Signature header against HMAC-SHA256 of raw body + secret
var computed = ComputeHmac(requestBody, _options.WebhookSecret);
if (!CryptographicOperations.FixedTimeEquals(computed, provided)) return Unauthorized();
Run Example »
This lesson uses terminal or setup steps. Run commands on your computer — the live editor appears on coding lessons.
What happened?
- Follow the practice steps below on ShopNest.API — typing code yourself is the fastest way to learn.
Try it yourself
- Read the real-world section and name which part of ShopNest.API uses this topic.
- Run dotnet run and test the endpoint in Swagger UI or curl.
- Change one value in the example (route, DTO field, or status code) and predict what will happen before you save.
- Change a route URL or DTO property and save — test again in Swagger or curl.
- Return the wrong status code on purpose (404 instead of 200) and see what the client shows.