Eric's Blog

Securing 5 WebAPIs with Auth0

March 12, 2015

Pre-release warning

This is written while I’m working with 5 beta 3. Things may change.

Stuff you should have already done

  • Setup an Auth0 dev account. It’s really easy. Go do it.
  • Followed the instructions Auth0’s QuickStart to setup your client app, or downloaded their started app.

Setting up 5

My first issue was that I was looking for a Jwt or OpenIdConnect middleware like the Auth0 quickstart says for old OWIN apps. Looks like that’s been merged into the plain old Microsoft.AspNet.Security.OAuthBearer NuGet package.

Step 1 - Add Nuget package

In project.json the add Nuget package to your dependencies:

"dependencies": {
    "Microsoft.AspNet.Security.OAuthBearer": "1.0.0-beta3"

Step 2 - Set it up in setup.cs

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerfactory)
    app.UseOAuthBearerAuthentication(o =>
        o.Authority = "YOUR AUTH0";
        o.Audience = "YOUR CLIENT ID GOES HERE";

	//everything else from the template


Step 3 - Change the JWT signing algorithm

FYI, This step may not be needed once everything is RTM, but it’s also the one that hung me up for a while.

Go to your Auth0 admin UI. Open the settings tab for the app you’ve created, and set the JsonWebToken Token Signature Algorithm to RS256.

auth0 jwt algorithm

Eric Haskins

Written by Eric Haskins, maker of things.