I've a situation where I'm creating a Blazor Server front end for an API, and that API may also be used directly by some other systems. Essentially some smaller customers might use the UI, others (perhaps larger with their own dev team) build their own UI and use the API. We control both sets of code (for the Blazor and the API).
Auth in the api is done (at the moment) by sending a userid and a password and getting a JWT Bearer token that is added to all subsequent requests.
Auth on the BS app is (at the moment) done using Azure AD B2C; the templating in VS makes it an easy setup and then no really specialist knowledge is needed to maintain and add new users
There isn't any special link between the two for now; both are in dev and the BS app just has a hard coded u/p for a single dev user inthe API side. At some point that needs to change so the API serves more than one customer via the UI
It seems I have a couple of routes I could go down:
Make the BS app use the API for auth; in my mind this looks like setting up something similar to what you get when you make a new BS app with "Individual Accounts" auth, except it doesn't use EF on a database with tables for tracking identity - it would probably use a custom store and usermanager that asks the API for auth instead of some DB, and then some (hopefully simple) mechanism of getting the returned token from the API into every httpclient that ends up being used to poke the API (they're abstracted away into proxies built by NSwag but it's easy enough to address because NSwag code calls a particular overridable method to setup the headers.. finding a way to have the httpclientfactory do it might be even easier)
Make the BS app and the API use AD B2C for auth. As a workflow I genuinely have no idea how that's done or what it looks like.
Of the two I'd prefer the latter because it hands off some additional responsibility to AD, such as maybe in future we want to have UI customers also do 2FA but I'm not really sure how to go about researching it. How do we go about sharing auth between the two systems?
I'm not looking for code; some rudimentary instructions on how to share the authenticated identity between the BS app and the API is really what I need. If it's not an achievable goal, what alternative mechanism for Blazor Server do I have that would allow easy sharing of a retrieved bearer across a everything the user might do in a "session" (I don't mind if they lose SignalR connection and have to log in again)?
If either of the approaches above look like I'm just making life hard work, and it should be done another way, an outline of the steps required to make it go would be ideal
Related
I'm extremely confused on how to use a centralized IDP with both authentication and authorization. The architecture for my project was to be a single web API and one React client. I wanted to keep things structured out into microservices just to try something more modern, but I'm having major issues with the centralized identity, as many others have.
My goal is fairly simple. User logs in, selects a tenant from a list of tenants that they have access to, and then they are redirected to the client with roles and a "tid" or tenant id claim which is just the GUID of the selected company.
The Microsoft prescribed way to add identity in my scenario is IdentityServer, so I started with that. Everything was smooth sailing until I discovered the inner workings of the tokens. While some others have issues adding permissions, the authorization logic in my application is very simple and roles would suffice. While I would initially be fine with roles refreshing naturally via expiration, they must immediately update whenever my users select a different tenant to "log in" to. However, the problem is that I cannot refresh these claims when the user changes tenants without logging out. Essentially, I tried mixing authorization with authentication and hit a wall.
It seems like I have two options:
Obtain the authorization information from a separate provider, or even an endpoint on the identity server itself, like /user-info but for authorization information. This ends up adding a huge overhead, but the actual boilerplate for the server and for the client is minimal. This is similar to how the OSS version of PolicyServer does it, although I do not know how their paid implementation is. My main problem here is that both the client and resource (API) will need this information. How could I avoid N requests per interaction (where N is the number of resources/clients)?
Implement some sort of custom state and keep a store of users who need their JWTs refreshed. Check these and return some custom response to the caller, which then uses custom js client code to refresh the token on this response. This is a huge theory and, even if it is plausible, still introduces state and kind of invalidates the point of JWTs while requiring a large amount of custom code.
So, I apologize for the long post but this is really irking me. I do not NEED to use IdentityServer or JWTs, but I would like to at least have a React front-end. What options do I have for up-to-date tenancy selection and roles? Right when I was willing to give in and implement an authorization endpoint that returns fresh data, I realized I'd be calling it both at the API and client every request. Even with cached data, that's a lot of overhead just in pure http calls. Is there some alternative solution that would work here? Could I honestly just use a cookie with authorization information that is secure and updated only when necessary?
It becomes confusing when you want to use IdentityServer as-is for user authorization. Keep concerns seperated.
As commented by Dominick Baier:
Yes – we recommend to use IdentityServer for end-user authentication,
federation and API access control.
PolicyServer is our recommendation for user authorization.
Option 1 seems the recommended option. So if you decide to go for option 1:
The OSS version of the PolicyServer will suffice for handling the requests. But instead of using a json config file:
// this sets up the PolicyServer client library and policy provider
// - configuration is loaded from appsettings.json
services.AddPolicyServerClient(Configuration.GetSection("Policy"))
.AddAuthorizationPermissionPolicies();
get the information from an endpoint. Add caching to improve performance.
In order to allow centralized access, you can either create a seperate policy server or extend IdentityServer with user authorization endpoints. Use extension grants to access the user authorization endpoints, because you may want to distinguish between client and api.
The json configuration is local. The new endpoint will need it's own data store where it can read the user claims. In order to allow centralized information, add information about where the permissions can be used. Personally I use the scope to model the permissions, because both client and api know the scope.
Final step is to add admin UI or endpoints to maintain the user authorization.
I ended up using remote gRPC calls for the authorization. You can see more at https://github.com/Perustaja/PermissionServerDemo
I don't like to accept my own answer here but I think my solution and thoughts on it in the repository will be good for anyone thinking about possible solutions to handing stale JWT authorization information.
There is a lot of information on the web about OAuth 2, its different types of flows and where/how to use them. I find that most of these resources discuss authenticating a user for an application, but I am struggling to understand what the best/correct approach would be when consuming third party APIs (i.e. when our own API is the "middleman" between a user and their data in a third party API).
With the help of an example scenario and some diagrams, I would be really grateful for advice/opinions on how I should properly implement integration with third party APIs and what the pros & cons of each approach are.
Starting point
As a starting point, suppose we have a web app, structured as follows:
Frontend - SPA (Angular), hosted with AWS S3 + Cloudfront
Backend - Node, running as stateless AWS lambda functions with AWS API Gateway
Auth0 for handling auth/signin etc. The frontend uses an Implicit OAuth2 flow to obtain access_tokens, which are stored in local storage and included as a header in all requests to the backend.
Potentially also native mobile app(s), consuming the same backend API.
Goal
Now suppose that we wish to add integration with Google Sheets. The new feature would allow users to use their own Google Sheets (i.e. stored in their own Google account) as a data source, with the app having read&write access to the sheet. There may be other integrations in the future, so I am assuming that other APIs would require a similar process.
Problem statement
In addition to the existing OAuth process (which allows users to sign in to the "MyApp" frontend and communicate with the "MyApp API"), there needs to be an additional OAuth process for users to connect MyApp to the third party Google Sheets API.
The documentation has two Quickstart examples, but neither seems to quite fit my needs:
Browser - https://developers.google.com/sheets/api/quickstart/js
Node.js (console app) - https://developers.google.com/sheets/api/quickstart/nodejs
The data from the third-party (Google) API is one of potentially several integration points, so intuitively it seems more logical (and more secure) that all communication with the Google Sheets API should happen in the MyApp API, and not on the frontend/client side. The MyApp API would fetch data, process/manipulate/format it in some way and then present it for display in the frontend or mobile apps.
We require access to each user's own data, so the Client Credentials flow is not suitable. I am focussing on the Implicit or Authorization Grant workflows.
Important note: The trickiness seems to come from the fact that the MyApp API is stateless, so there is no long-lived session in which to store tokens. On that basis, it seems like tokens need to be stored either in the frontend (e.g. local storage/cookies etc) or in a backend database.
Below is my interpretation of two possible approaches. I'd appreciate thoughts/corrections.
Option 1: Implicit flow - tokens stored FE, passed along to BE which then makes requests to Google
Pros:
Allows access to user's own data
Simpler flow, access_token retrieved immediately without needing the code step
Less steps to implement between initial sign-in process and actually obtaining data
No need for a backend database, can resend the token with each request
Cons:
Frontend (browser) has access to Google access_token which seems unnecessary and is a potential security concern
It seems like a strange process to pass the access_token from FE to BE, purely to allow BE to then use that token to make another request
I'm not sure how we would refresh/renew tokens since I understand that storing refresh_tokens on the client is bad practice. It would not be a good user experience if the user had to frequently sign in to reconnect their account
Option 2: Authorization Code Flow - all communication with Google via BE, tokens stored in BE database
Pros:
Allows access to user's own data
Other than the code-request / consent page, all communication with Google is implemented backend, so the tokens are not accessible on the client
Client secret can be used from the BE
Cons:
More complex flow, requires extra steps
Given that the BE is stateless, it's not clear how best to store the tokens. It seems like it would require storing them in a database which is extra complication and seems like it would have security implications - how would you properly secure / encrypt the access_token/refresh_tokens in said database?
Conclusion
Given that the data processing is to happen on the backend, option 2 seems slightly more suitable because the sensitive tokens can be hidden from the frontend app, and several clients (web frontend, mobile apps) have less obligation to be involved in the process with the exception of the initial sign in / user consent. However I’m not sure whether having a database full of user auth tokens is a good idea or how I could properly protect this database.
The good news is that both options are perfectly valid and equally secure. The concern about a short-lived Access Token being in the browser isn't an issue. Equally, if you only held the tokens on the BE, then you would need to implement your own client authentiation/session/JWT blah blah, which presents the same attack surface.
I've done both, and am currently migrating from BE to FE. In my case the reason is that everything I need to do, I can do on the FE, so I end up with no BE at all. This isn't strictly true since I do some onboarding/payment with the BE, but that's about all.
So the best approach depends on factors beyond those in your question, such as the nature of app, what the BE cost is and how important that is, what your devops skillsets look like for maintaining two environments, to what extent a BE is required anyway, vs being completely optional.
I want to create a custom API that behind the scenes, call number of other APIs which use OAuth 2.0 for authentication. I want to manage this internally so that my custom endpoint somewhat abstract this.
Or to begin with I want to do what app like buffer (https://buffer.com) do - where you connect to different social services and than post your status.
How can I achieve this in .NetCore ?? I don't want to login with these (a lot of samples are catering this scenario), user login is different than this. I just want to establish these connections (like API Connections if you look at Azure API Management) and then perform some operations against those endpoints.
I hope i convey my point. please let me know if this isn't clear.
Thanks
Sanjay
OAuth2 systems are all based on the same workflow.
here's an authorization url, you pass some ids in an authorization header, if everything is correct you get a token, you then use the token to do whatever you are allowed to do. What changes are the credentials you use for authentication and the urls you hit for the various parts of this workflow.
You could write your own OAuth2 library which deals with all this, that's pretty much what I did and simply changed the details for every specific system I had to interact with.
This being said you can always use one of the existing implementations to connect to the various systems you care about, they all have an API you could use, all you have to do is make sure you follow the OAuth2 flow correctly.
I have a JSON REST API written in Symfony 2.7, and I want to authenticate & authorize users. This is my first time doing this, so I have some doubts/questions.
For that, I thought several methods:
User & password, and then save a session in the back end
Same as 1), but add an "apiToken" (randomly generate when user register) and then sending back & forth the apiToken in every single request to check user identity.
Use OAuth (which I'm currently reading about it).
I read that using OAuth for a simple API is like an "overkill", but on the safe side it sticks to standards and also allows me to use it when using my API with mobile devices and different platforms.
Also, I don't know too much about security flaws of using method 1) or 2).
I know this is maybe based on opinions, but I don't know any other site to post this question, as Symfony official mailing was shut down and migrate here it seems.
As you seems to know, your question is too opinion based.
If I can give you some advices (too long for a 600chars comment),
OAuth is powerful, but so much free.
I mean that you can easily implement it sort as everything works well while having a set of potential security issues without being aware of their existence.
Libraries and bundles providing OAuth are hard to maintain because of the new security issues regularly found.
On the other hand, if you need the benefits of OAuth (be a client and/or a server, compatible with the most part of social networks), go learn OAuth and do your experience with it.
Otherwise, use a simple credentials/request token two-step authentication.
See the JWT Authentication tutorial by KnpLabs,
Symfony Guard Authentication by Ryan Weaver,
and the great LexikJWTAuthenticationBundle, easy to implement and to use.
I am building an ASP.NET MVC 3 app that has both a www front-end (www.example.com) and a developer API (api.example.com). I'd like to make a simple service available to developers where they sign up for a key and make REST calls with it. I'm unclear on a few things:
1) How should I generate and store keys? Is it acceptable to store them in plain text in the database or should I hash and salt them?
2) How do I authorize API calls? I'm guessing I don't want to do this via ASP.NET Membership for this.
Things like rate-limiting seems straight-forward once I understand those two issues.
1) That's really up to you. I've seen it done completely differently in different API's I've worked with. Some keys closely resemble GUID's, others are clearly just random strings, but the important thing is that they're unique and not easily guessable. As far as how you store it in the database, how much effort you put into protecting your data really depends on the level of sensitivity of users' accounts. If the nature of the service you're providing is highly confidential and/or you may end up being audited, then you should take whatever means are necessary to protect the data (using a 1-way hash and salting). My personal philosophy is to keep things as simple as possible until there's a reason to introduce added complexity, but I've worked on sites that used 1-way hashing with salts for authentication.
2) That depends on who's going to be using your service. You could use the built-in ASP.NET Forms Authentication Membership Provider, and even integrate it with your public website, but that will limit the usage of your API to developers using a platform that supports cookies on HttpProxies, and will make your API harder to follow. Most REST-ful services I've had experience with have used a combination of basic authentication and SSL, which will provide the broadest range of developer support, but will be more complicated to implement on your side. On the server side you'll have to capture the user credentials out of the HTTP headers and authenticate them against your user database.