How to validate access token with implicit flow on backend? - authentication

I didn't make such decisions with implicit flow (I know it's not so good to use it), but I currently have situation where I have to validate my access token on backend(Java 8). Is it okay for every request with access token additionally call oidc provider to check if token is active(not revoked, with valid lifetime) or there is more appropriate way how to handle it? Anyway thanks

Related

Recommended Format for Refresh Token

I am making an application that generates refresh token that implements JWT token authentication, and I am not sure what format should I use to identify the refresh token. Initially, I thought that it should be in JWT token format, but based on my googling, it seems like it is represented in a UUID or hashed format? Just wondering whether I should make it JWT token format, or it does not matter in the case of refresh token?
Thanks in advance for helping to clarify this issue.
From here https://developer.okta.com/docs/guides/refresh-tokens/main/ refresh token response it shows the refresh token format is not in JWT format.
First decide how you want to model this, which might work like this:
User authenticates (and optionally consents)
Create a delegation to represent the user action
Delegation is stored as a database row
Fields include sub, client_id, refresh_token_hash, scopes_issued, claims_issued, issuance time, expiry time
Subsequent token requests are validated against the persisted state
The hash might be the returned to clients, or they may be given a different identifier. It is a pointer to backend state.
You might also need to implement support for refresh token rotation, revocation, auditing of tokens issued and so on. Consider using an authorization server, as described in RFC6749, to handle this stuff for you.

In JWT, why do you need a refresh token instead of just re-logging in?

I understand the concept of JWT and the need for a refresh token.
As far as I understand, it's to add an additional layer of security so even if the N number of access tokens generated from the fresh tokens are leaked, as long as you keep the refresh token in a safe place (a separate place) it's safe. I get that.
But what I don't understand is, why can't you just do the following?
A client authenticates
The server gives the client an access token.
After a while, the client's JWT expires. The client knows when it expires because it's baked into the token definition.
The client re-authenticates with the server.
The server re-issues a new unique access token.
Doesn't this solve the same problem of a more complex refresh token + access token pattern? I'm sure I'm missing some details. Are there use cases where this model doesn't work (or work)?

Implementing public API keys with microservices

For most client applications and UI approaches JWTs seem to be a good way to carry tokens for an OAuth based approach. This allows decoupling of a User/Auth service and the services that are actually being accessed.
Given this architecture
My question is: in the case of public APIs (ie Github or Slack) where a bearer key is generated with specific roles. How is that key authorized in a microservice architecture? Do those types of keys just require that the Auth service gets queried with every request?
Could an API gateway mitigate this? I would like to understand if a solution exists where there is minimal communication between services. Thank you!
Normally, this is solved using scopes. The scopes are permissions given to a user to do certain operations,for example there will be a scope for read a repository, another for update it, another one for delete etc..
These scopes are tied to the token and normally are requested by the user himself or added automatically depending on the user type. And the same as the authentication process, they could be included in the token itself coded as a claim in a jwt or they could be requested or checked by calling an oauth server when one operation is requested.
The advantages of include them in jwt is that there is not need to call an external server every time an operation is requested so there is a lower latency and less bandwith is required, also you remove a point of failure. Obviously if this solution is used the token must be properly signed or even encrypted to avoid possible manipulations.
However it has also drawbacks, and the most dangerous one is that the token cannot be revoked because this information cannot be included in the token and the service that check if the token is valid only can access the data contained in the token itself. Because of this, this kind of tokens are normally issued with a little expiry time so in case of the token is stolen, the validity of it will be very limited

How to get identity in API using OpenID Connect

I'm trying to follow OpenID Connect best practices. For the simple scenario of calling API from application the OpenID Connect suggest to pass the Access Token (which is not included user identity), and if the API in some points need the user identity it should call /userinfo endpoint of OpenID Connect provider.
So the question is: Is it the best way to get the user identity in API?
Assume I have an end point named CreateOrderForCurrentUser() so each time any user call this api I need to call the /userinfo endpoint, it seems too much cost for calling an api.
Why I don't pass the Identity token to the API?
Or Why I don't put some identity claims in Access token?
Should I use HOK Token instead of Access token?
Any idea please.
It seems here is kind of same as my question: Clarification on id_token vs access_token
And he respond in comments: https://community.auth0.com/t/clarification-on-token-usage/8447#post_2
Which as my understanding means: put some identity claims in Access token (Custom Claims) and rely on that in the API.
But still it doesn't make sense. The OIDC insist to not use Access token as Identity and now we are going to add identity claims inside Access Token. Could any one clarify that?
ID_Token is used for your client app tells the app who you are , the audience of the ID Token is the id of your client app , with access token , API/resource knows whether authorized to access the API and perform specific actions specified by the scope that has been granted.
By default , it will include user identifier in access token(sub claim) , so you should know which user when calling CreateOrderForCurrentUser function . You could customize the access token to include more user related claims if needed . But i would suggest to simplify the access token , and you could use access token to acquire user information by invoking user's API endpoint .
I asked the same question in Auth0 Community and there is a discussion about it that might be helpful for others who have the same issue.
I copy the same answers here:
markd:
You are correct that you should not use an access token as proof of identity, but before you get to your API you should have already authenticated the user and received an id_token for them. If you have already authenticated the user via OIDC, as far as I know there’s nothing wrong with adding custom claims to the access token to pass data to your API. Your API could also use the client credentials grant type to pull data from Auth0.
Me:
I’m looking for the best practices. I want to be sure adding identity claims to the access token and rely on that in API does not broke any thing and is based on best practices or maybe the best practice is always call the /userinfo endpoint in API and don’t rely on Access token identity claims.
The API doesn’t know about the authentication process and don’t care about that. Any one any how pass the signed Access token to the API, it would be accepted. Now in API point of view is that proper way to rely on identity claims in Access Token? I have doubts. But I would be happy if we could ignore calling the /userinfo end point each time.
jmangelo:
I can share some (hopefully) informed views on this subject, but please do take them with a grain a salt and question stuff you disagree with or you don’t consider clear enough. When it comes with software the devil is on the details and in the security landscape it’s even more true so you need to consider best practices as what will likely be recommended for the majority of the scenarios and also what will likely be less risky; it does not mean that nothing else is possible.
For example, although the recommendation is indeed to use access tokens in requests to API’s this does not mean that there isn’t a specific scenario where technically it would also be okay to send an ID token instead.
Focusing on your particular questions and starting with the last one (3); we should not compare HOK and access tokens because they are not at the same level. In other words, you could question if in your scenario you should use bearer tokens or HOK tokens as this way and using the terminology of your linked page you would be choosing between two token profiles where each give you different characteristics.
At this time, the access tokens issued by the Auth0 service as part of API authorization are bearer access tokens so this question has only one answer if using the Auth0 service.
Jumping to the first question; it’s not that you cannot pass the ID token to the API, it’s just that the scenarios where that would be adequate are much more constrained. For example, an ID token is issued with the client identifier as the audience; it’s common to have multiple client applications so you have just coupled your API to how many client applications you have, because assuming you will validate the audience of the ID token, your API would now need to know the identifiers of every client.
For question (2) which I assume is also interested in why call /userinfo if you can include claims in the access token. I believe this can depend a lot on requirements and/or personal preferences. At this time the only format supported when issuing an access token to a custom API is the JWT format.
The above means that you have a self-contained token that once issued the API can mostly validate independently which is great in terms of scalability because the API does not need to make (frequent) external calls for validation purposes.
However, being self-contained this immediately means that any data you include directly in the token will be considered the truth for the lifetime of the token itself. If instead the API is calling /userinfo or even the Management API directly then you ensure fresh data at the cost of network overhead.
In conclusion, in my personal view the choice between network calls and embedded claims is more tied to the characteristics of the data you are interested in that just from a best practices point of view.
As a final note, even without any addition of custom claims an access token issued by the service in association to a custom API already conveys user identity. In particular, given the access token is a JWT, the sub claim will contain an identifier that uniquely identifies the end-user that authorized the current application to call the API on their behalf.

how to use and store token from oauth2 to do authentication

sorry if this is question is too broad, but I have to ask this since I'm learning web development and I feel if don't ask I won't know.
So, I'm doing authentication using oauth2, and right now I'm already at point where I successfully authenticate user, and now I'm receiving what they call tokens. The question is, how do you use token to authenticate user to your own server?
I'm thinking something like creating a cookie that maps to a token, so when user acts, each time I'll get a cookie and I know that this is user A. Is method like this safe or not? If not, in what way people usually use the token? Although this is only a hobby project, I'd like to be "as real as possible". Any thoughts?
As per my knowledge Oauth2.0 provides InMemoryTokenStore and JdbcTokenStore for persisting tokens. When a request comes from an authenticated user Oauth2.0 will check if it has a valid token already. In case it doesn't it will create one.
Basically usage of tokens depends on the grant-type you are using . Following are the two commonly used grant types -
1) Implicit - The token is send back in the url as a parameter and is included in the subsequent request* in the parameter.
2) Authorization Code - In this case the token is generated and set in the header of the request*.
*the request here is the one which is finally sent to resource server for accessing protected resources.
I think you dont need to create a cookie for storing tokens. In case you are using Authoziation Code grant type which is the default, Oauth2.0 will use session for storing state and code which will be used for retrieving token.