I am building an API meant to be sold to various clients. These clients will be given an API Key or something similar and they'll use the API in a widget on their website.
The end users of the clients' website must be able to use the widget anonymously (no login).
Workflow:
My current idea is to have the Client's server retrieve a temporary key and use that in the webpage. The End user's browser will use that temporary key to call our API.
Is there any reason why this is not a good practice and/or insecure?
Or is there a better good practice solution? Can I for exmaple use OAuth 2 for this?
You need to secure your API from the clients app. So, for that you can use OAuth 2 with Client Credentials grant type and setup each client as an app so they each get their own set of key/secret credentials.
Since you don't know anything about the end user, but still need to track them, require an endUserId custom header on every request to your API and you'll just have to trust the client to provide you with a valid id for the end user making the request.
To setup OAuth, use an existing library or OAuth service. I don't recommend writing your own. If you can spend some money, Okta and Auth0 are good choices. If your API is written in .net, you can use IdentityServer as a free option.
I'm putting together a personal React site and want to send requests to an AWS API Gateway. However, I just want my site to be able to pull data. There will be no user model and every auth model I've ever used requires the user to do something with sign-in, be it user/pwd or AD. Can someone guide me to a model that covers this scenario?
One common approach is to use a Cognito Identity Pool with "Unauthenticated Identities" enabled. You can secure your API gateway endpoints using IAM, and require requests to be sig4 signed.
With this approach, Cognito is used only in a kind identity broker capacity, not as an actual identity provider. You do not need to create a User Pool or use any other identity management features of Cognito. In this capacity, Cognito is essentially just a thin layer between your code and the underlying STS APIs that produce the IAM keys your application needs.
Using the Cognito SDK, you request temporary IAM credentials (access key, secret key, session token) that can be used to sign the requests.
This answer outlines one way to accomplish this. When the protected AWS resource you want to access is API Gateway, your code may look something like the example near the end of this post.
I typically either use aws-api-gateway-client, as the example does, or aws4 with axios to sign requests.
As noted in the linked to answer above, I normally use AWS.config.credentials.get(), rather than AWS.CognitoIdentity.getCredentialsForIdentity() to actually get the IAM keys (as in this doc).
The signed requests then include an Authorization header that is very difficult to counterfeit. I don't want to suggest that this approach is bulletproof, but it does at least give you a reasonable level of confidence that your API Gateway endpoints are only being successfully invoked by your application.
I have a website allowing authenticated users to submit and edit data. I also want to offer a REST API as part of a chargeable service.
Now the problem is that a non-paying user could theoretically use the same calls my website uses as API for authentication and sending data from his external application since it is very easy in the browser to see the endpoint what and how exactly the data is being sent to a website.
How can I protect my website from such usage and force the user to use API for external access?
Actually you cannot prevent people making requests to a public API. You can just validate the user when a request arrives. So there are more than one approach to solve this problem.
I would provide a token per session for each user and validate the rest API request at back-end.
Use OAuth2. So you will give paid user secret id and key then they will ask for the access token to access the API's using secret id and key.
Read about public/private key encryption https://en.wikipedia.org/wiki/Public-key_cryptography
Read about oAuth
https://oauth.net/2/
I have used passport to implement oAuth2 in laravel. passport is oAuth2 implementation and available in other languages also.
Our APIs (delivered by a third party) are using Tokens in order to ensure authorized access only. Our new website should not be server-to-server but mostly front end, i.e. the token would be visible in the script. We're now checking how to secure the API for a frontend website and I have to propose ways to my boss. However, I've never had to do something with API securing, could you please help me by telling me where to read / state of the art solutions?
I've already begun to look into OAuth1a, OAuth2, OpenID but can't (yet) really get a direction to further investigate.
You should still use a token, but you have to make sure that the token doesn't grant you full access to the API.
Tokens need to be specific to the user who's using the application, and the token can only grant API access to the specific functions that the user is allowed to do.
For now I would ignore OAuth1 and OpenID and only look at OAuth2. There's enough features there to do what you want, and it's simpler than the rest.
Preface
I'm developing several web services and a handful of clients (web app, mobile, etc.) which will interface with said services over HTTP(s). My current work item is to design an authentication and authorization solution for the product. I have decided to leverage external identity providers, such as Facebook, Google, Microsoft, Twitter, and the like for authentication.
I'm trying to solve the problem of, "when a request comes to my server, how do I know who the user is and how can I be sure?". More questions below as well...
Requirements
Rely on external identities to indicate who I'm dealing with ('userId' essentially is all I care about).
The system should use token-based authentication (as opposed to cookies for example or basic auth).
I believe this is the right choice for scaling across multiple clients and servers while providing loose coupling.
Workflow
Based on my reading and understanding of token-based authentication, the following is how I imagine the workflow to be. Let's focus for now on Facebook in a web browser. My assumption is that other external identity providers should have similar capabilities, though I have not confirmed just yet.
Note, as of writing, I'm basing the following off of Facebook login version 2.2
Client: Initiates login to Facebook using the JavaScript SDK
Facebook: User authenticates and approves app permissions (to access user's public profile for example)
Facebook: Sends response to client which contains user’s access token, ID, and signed request
Client: Stores user access token in browser session (handled by SDK conveniently)
Client: Makes a request to my web service for a secure resource by sending along the user’s access token in the authorization header + the user’s ID (in custom header potentially)
Server: Reads user access token from request header and initiates verification by sending a request to the debug_token graph API provided by Facebook
Facebook: Responds back to the server with the user access token info (contains appId and userId)
Server: Completes verification of the token by comparing the appId to what is expected (known to itself) and the userId to what was sent on the client request
Server: Responds to the client with the requested resource (assuming the happy authorization path)
I’m imagining steps 5-9 would be repeated for subsequent requests to the server (while the user’s access token is valid – not expired, revoked from FB side, app permissions changed, etc.)
Here's a diagram to help go along with the steps. Please understand this system is not a single page application (SPA). The web services mentioned are API endpoints serving JSON data back to clients essentially; they are not serving HTML/JS/CSS (with the exception of the web client servers).
Questions
First and foremost, are there any glaring gaps / pit falls with the described approach based on my preface and requirements?
Is performing an outbound request to Facebook for verifying the access token (steps 6-8 above) per client request required / recommended?
I know at the very least, I must verify the access token coming from the client request. However, the recommended approach for subsequent verifications after the first is unknown to me. If there are typical patterns, I’m interested in hearing about them. I understand they may be application dependent based on my requirements; however, I just don’t know what to look for yet. I’ll put in the due diligence once I have a basic idea.
For instance, possible thoughts:
Hash the access token + userId pair after first verification is complete and store it in a distributed cache (accessible by all web servers) with expiry equal to access tokens. Upon subsequent requests from the clients, hash the access token + userId pair and check its existence in the cache. If present, then request is authorized. Otherwise, reach out to Facebook graph API to confirm the access token. I’m assuming this strategy might be feasible if I’m using HTTPS (which I will be). However, how does performance compare?
The accepted answer in this StackOverflow question recommends creating a custom access token after the first verification of the Facebook user token is complete. The custom token would then be sent to the client for subsequent requests. I’m wondering if this is more complex than the above solution, however. This would require implementing my own Identity Provider (something I want to avoid because I want to use external identity providers in the first place…). Is there any merit to this suggestion?
Is the signedRequest field present on the response in step #3 above (mentioned here), equivalent to the signed request parameter here in the ‘games canvas login’ flow?
They seem to be hinted as equivalent since the former links to the latter in the documentation. However, I’m surprised the verification strategy mentioned on the games page isn’t mentioned in the ‘manually building a login flow’ page of the web documentation.
If the answer to #3 is ‘Yes’, can the same identity confirmation strategy of decoding the signature and comparing to what is expected to be used on the server-side?
I’m wondering if this can be leveraged instead of making an outbound call to the debug_token graph API (step #6 above) to confirm the access token as recommended here:
Of course, in order to make the comparison on the server-side, the signed request portion would need to be sent along with the request to the server (step #5 above). In addition to feasibility without sacrificing security, I’m wondering how the performance would compare to making the outbound call.
While I’m at it, in what scenario / for what purpose, would you persist a user's access token to a database for example?
I don’t see a scenario where I would need to do this, however, I may be overlooking something. I’m curious was some common scenarios might be to spark some thoughts.
Thanks!
From what you describe I'd suggest to use a server-side login flow as described in
https://developers.facebook.com/docs/facebook-login/manually-build-a-login-flow/v2.2
so that the token is already on your server, and doesn't need to be passed from the client. If you're using non-encrypted connections, this could be a security risk (e.g. for man-in-the-middle attacks).
The steps would be:
(1) Logging people in
You need to specify the permission you want to gather from the users in the scope parameter. The request can be triggered just via a normal link:
GET https://www.facebook.com/dialog/oauth?
client_id={app-id}
&redirect_uri={redirect-uri}
&response_type=code
&scope={permission_list}
See
https://developers.facebook.com/docs/facebook-login/manually-build-a-login-flow/v2.2#login
(2) Confirm the identitity
GET https://graph.facebook.com/oauth/access_token?
client_id={app-id}
&redirect_uri={redirect-uri}
&client_secret={app-secret}
&code={code-parameter}
https://developers.facebook.com/docs/facebook-login/manually-build-a-login-flow/v2.2#confirm
(3) Inspect the access token
You can inspect the token as you already said in your question via
GET /debug_token?input_token={token-to-inspect}
&access_token={app-token-or-admin-token}
This should only be done server-side, because otherwise you'd make you app access token visible to end users (not a good idea!).
See
https://developers.facebook.com/docs/facebook-login/manually-build-a-login-flow/v2.2#checktoken
(4) Extending the access token
Once you got the (short-lived) token, you can do a call to extend the token as described in
https://developers.facebook.com/docs/facebook-login/access-tokens#extending
like the following:
GET /oauth/access_token?grant_type=fb_exchange_token
&client_id={app-id}
&client_secret={app-secret}
&fb_exchange_token={short-lived-token}
(5) Storing of access tokens
Concerning the storing of the tokens on the server, FB suggests to do so:
https://developers.facebook.com/docs/facebook-login/manually-build-a-login-flow/v2.2#token
(6) Handling expired access tokens
As FB doesn't notify you if a token has expired (and if you don't save the expiry date and compare this to the current timestamp before making a call), it's possible that you receive error messages from FB if the token got invalid (after max. 60 days). The error code will be 190:
{
"error": {
"message": "Error validating access token: Session has expired at unix
time SOME_TIME. The current unix time is SOME_TIME.",
"type": "OAuthException",
"code": 190
}
}
See
https://developers.facebook.com/docs/facebook-login/access-tokens#expiredtokens
If the access token becomes invalid, the solution is to have the person log in again, at which point you will be able to make API calls on their behalf once more. The login flow your app uses for new people should determine which method you need to adopt.
I dont' see any glaring gaps / pit falls, but I'm not a security expert.
Once your server has verified the given token (step 8), as you said:
The accepted answer in this StackOverflow question recommends creating a custom access token after the first verification of the Facebook user token is complete. The custom token would then be sent to the client for subsequent requests. I’m wondering if this is more complex than the above solution, however. This would require implementing my own Identity Provider (something I want to avoid because I want to use external identity providers in the first place…). Is there any merit to this suggestion?
IMHO is the way to go. I would use https://jwt.io/ which allows you to encode values (the userId for example) using a secret key.
Then your client attach this token to every request. So you can verify the request without need to a third party (you don't need database queries neither). The nice thing here is there is no need to store the token on your DB.
You can define an expiration date on the token, to force the client authenticate with the third party again when you want.
Let's say you want your server be able to do some action without the client interaction. For example: Open graph stories. In this scenario because you need to publish something in the name of the user you would need the access token stored on your DB.
(I can not help with the 3 and 4 questions, sorry).
Problem with Facebook is that they do not use OpenId connect on top of Oauth (https://blog.runscope.com/posts/understanding-oauth-2-and-openid-connect).
Thus resulting in their custom ways of providing Oauth authentification.
Oauth2 with OpenId connect identity services usually provide issuer endpoint where you can find URL (by appending ".well-known/openid-configuration") for jwk's which can be used to verify that JWT token and its contents were signed by the same identity service. (i.e access token originated from the same service that provided you jwk's)
For example some known openid connect identity providers:
https://accounts.google.com/.well-known/openid-configuration
https://login.microsoftonline.com/common/v2.0/.well-known/openid-configuration
(btw it is not a coincidence that Attlasian provides only these two services to perform external login)
Now as you mentioned, you need to support multiple oauth providers and since like Facebook not all providers use same configuration of oauth (they use different JWT attribute names, toke verification methods, etc. (Openid connect tries to unify this process)) i would suggest you to use some middleware identity provider like Oauth0 (service not protocol) or Keycloak. These can be used with external identity providers (Social pages as you mentioned) and also provides you with custom user store.
Advantage is that they unify authentication process under one type (e.g both support openid connect). Whereas when using multiple oauth providers with not unified authentication workflow you will end up with redudant implementations and need for merging different information's under one type (this is basically what mentioned middle-ware identity providers solve for you).
So if you will use only Facebook as identity provider in your app then go for it and make implementation directly for Facebook Oauth workflow. But with multiple identity providers (which is almost always case when creating public services) you should stick with mentioned workaround or find another one (or maybe wait till all social services will support Openid connect, which they probably wont).
There may be hope.. This year, Facebook have announced a "limited login" feature, which, if they were to add to their javascript sdks would certainly make my life easier:
https://developers.facebook.com/blog/post/2021/04/12/announcing-expanded-functionality-limited-login/
At the time of writing, I can only find reference to iOS and Unity SDKs, but it does seem to return a normal JWT, which is all I want!