Last week, I received an email from someone who was asking me whether ASOS or OpenIddict could be used with Azure Key Vault (Microsoft's cloud-based Hardware Security Module offer). Since it's quite a recurring question, I thought it was worth writing a blog post to demonstrate how to do that.
So, good news: this is definitely possible! And thanks to a new project released recently by Oren Novotny, this has never been so easy.
What is a Hardware Security Module?
A HSM is a hardened device – generally a PCI board or a standalone appliance – that is exclusively dedicated to cryptographic operations (data encryption/decryption, data signing/verification, key management, etc.). Though HSMs are complex systems, the main idea is actually simple: key material should never leave the HSM's secure enclave, which is protected against physical or digital intrusions.
As such, when a service requires encrypting or signing data (e.g a JWT access token in our case), it has to ask the Hardware Security Module to execute the cryptographic operation on its behalf.
Use Azure Key Vault to sign the JWT tokens issued by ASOS/OpenIddict
Create a new HSM key and register a client application allowed to access it
If you don't have a key yet, you'll have to create one, register a new application in the Azure Active Directory database and grant it an access to your signing key. If you're not familiar with this procedure, I encourage you to read this tutorial or watch the corresponding video:
Azure Key Vault actually offers two pricing tiers: standard and premium. To be able to generate a HSM-protected key (referred to as "hardware key"), you must choose the premium tier when creating your vault. Don't worry, the difference between the two tiers is unbelievably marginal: at the time of writing, $1/month per RSA 2048-bit key.
Earlier today, a patch release for the OpenID Connect server middleware (aka ASOS) was pushed to NuGet.org.
Here's the changelog:
The MatchEndpointContext.Options property that had been accidentally removed in 1.0.0 has been reintroduced in 1.0.1 (f17d9a4).
An exception is now automatically thrown at startup when registering a signing certificate that is no longer or not yet valid (583be00).
Internal code relying on JwtSecurityTokenHandler.CreateToken()/WriteToken() has been updated to use JwtSecurityTokenHandler.CreateEncodedJwt() to ensure JWT tokens are not signed twice (a499f11).
To migrate to the 1.0.1 packages, update your project.json/.csproj project file(s) manually or run the following command in the Package Manager Console:
Today is a great day for me, as I just uploaded the ASOS 1.0.0 packages to NuGet.org, concluding a 3-year work on this library. A huge thanks to everyone – clients, sponsors, contributors, users – who helped me make this possible: ASOS wouldn't exist without your support!
Migrating to 1.0.0
Migrating from ASOS RC1 to RTM should be rather smooth as no major change was adopted in this release, but there's an important requirement you must comply with to ensure your application still works correctly after the migration: you must also update the validation/introspection middleware to the 1.0.0 RTM version (the previous beta versions won't deliberately work):
If you use recent OpenIddict packages (that use ASOS 1.0.0) or if you explicitly downloaded AspNet.Security.OpenIdConnect.Server or AspNet.Security.OAuth.Introspection 1.0.0 from the aspnet-contrib MyGet feed, consider clearing your NuGet packages folder, as the bits published on NuGet.org slightly differ from the packages initially published on MyGet.org (e.g the ASOS package uploaded to NuGet.org offers ECDSA support when running on .NET Framework 4.7).
For that, close your VS instances, go to C:\Users\[username]\.nuget\packages (on Windows) or ~/.nuget/packages (on macOS) and remove the following folders:
Then, re-open VS and restore your projects or run dotnet restore to download the latest binaries from NuGet.org.
Support lifecycle
No software can reasonably ship without a solid support lifecycle and ASOS is no exception. To keep things simple, I've decided to adopt the same support policy as the one used by Microsoft for the .NET Core platform, which means the aspnet-contrib 1.0.0 RTM packages will get critical fixes and security patches until at least July of 2018.
What's next?
The next big step is to port ASOS to the new ASP.NET Core 2.0 authentication stack I helped redesign, as the 1.0 ASOS bits won't work at all due to the massive breaking changes adopted in 2.0 (e.g authentication handlers are now registered in the DI container and a unique authentication middleware handles everything at the pipeline level, in Startup.Configure(IApplicationBuilder app).
This version – the latest before RTM – includes a few design changes that will directly impact your own code:
The built-in claims mapping feature was removed
Starting with RC1, ASOS no longer includes a built-in claims mapping feature, which means claims like ClaimTypes.NameIdentifier, ClaimTypes.Name or ClaimTypes.Role are no longer mapped to their OpenID Connect/JWT equivalents (sub, name, role).
Concretely, if you have code like that in your authorization provider class, you should update it to use the OpenID Connect claims instead of the legacy claims exposed by the static ClaimTypes class:
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var identity = new ClaimsIdentity(OpenIdConnectServerDefaults.AuthenticationScheme);
// Configure ClaimsIdentity to use the OpenID Connect claims instead of // the legacy ClaimTypes claims to populate the ClaimsIdentity.Name property // and determine how roles are resolved when calling ClaimsPrincipal.IsInRole(...). var identity = new ClaimsIdentity( OpenIdConnectServerDefaults.AuthenticationScheme, OpenIdConnectConstants.Claims.Name, OpenIdConnectConstants.Claims.Role);
You're actually free to keep using the ClaimTypes claims, but the OpenID Connect server middleware will throw an exception if you don't (at least) add the sub claim:
InvalidOperationException: The authentication ticket was rejected because it doesn't contain the mandatory subject claim.
If you use the JWT bearer middleware, you'll also want to disable its own claims mapping feature and update the token validation parameters to use the dedicated JWT name/role claims:
The introspection middleware now uses name and role as the default claim types
In the same vein, the introspection middleware was updated to use name and role as the default claim types (instead of ClaimTypes.Name and ClaimTypes.Role):
// Override the default claim types used by the introspection middleware: options.NameClaimType = "custom_name_claim"; options.RoleClaimType = "custom_role_claim"; });
Unfortunately, this change makes old authorization codes, access and refresh tokens incompatible with the new format (and vice versa). In practice, this means that you can't use tokens issued by ASOS RC1 with old versions of the validation middleware (or with the OpenID Connect server middleware itself): such tokens will be automatically rejected.
To make sure everything runs smoothly, migrate to the latest version of the validation middleware (1.0.0-beta1-final).
Registering a signing key is no longer required when using the default access token format
Starting with RC1, ASOS now includes a "degraded mode" that allows you to use it without registering a signing key or a signing certificate (ephemeral or not) if you don't opt for JWT access tokens and don't use the implicit or hybrid flows.
Concretely, using AddEphemeralKey() or AddCertificate() is no longer mandatory if you use non-interactive flows like password or client credentials AND the default access token format.
No new release candidate is currently planned, which means the next version will be the RTM package.
The next (and last) step is to rework the XML documentation. Depending on how well this work item goes, the RTM bits should be published at the end of the month or in April. If you're willing to contribute to this stask, don't hesitate to ping me.
Last year, Mike Rousos posted a great post about token authentication on the .NET blog and demonstrated how you could leverage ASP.NET Core Identity and OpenIddict to create your own tokens in a completely standard way.
Since then, many people emailed me to know if using ASP.NET Core Identity was really mandatory. Good news! While the first OpenIddict alpha bits were tied to Identity, the two have been completely decoupled as part of OpenIddict beta1 and beta2. Concretely, this means you can now use OpenIddict with your own authentication method or your own membership stack.
Get started
This post was updated to include code snippets demonstrating how to register OpenIddict in an ASP.NET Core 2.x application. When using OpenIddict in an ASP.NET Core 2.x application, make sure you're referencing the OpenIddict 2.x packages.
Update your .csproj file to reference the OpenIddict packages
For this demo, you'll need to reference 2 packages:
OpenIddict, that references the core services, the token server and the validation services.
OpenIddict.EntityFrameworkCore, that contains the Entity Framework Core stores.
