I am exposing REST API's via an API Gateway so the requests go
Client => API Gateway => Back-end.
My back-end REST API's need to know about 2 users
1: Target User (on some requests)
the API needs this data for its action eg: groups/{abc}/add-user needs to know which user to add to a group
2: Calling User (on every request):
the API needs to check that this user is allowed to perform the action eg: only a group admin may add another user to the group.
I don't want other developers to get confused when looking \ adding to my API's so I want to create a convention. Is it a good idea to add the calling user ID as a header on every request?
eg: "user-context": "12345"
Before everyone screams "INSECURE!!!!", I should add some info to put your minds at ease
The calling user is allowed to know their user-id. It's not a problem
The target user is not identified by their real user-ID but by an obfuscated ID
The calling-user-id is actually passed in a signed JWT to my API Gateway. The API-Gateway validates the JWT, takes the calling-user-id and adds it to the back-end request. What i'm really asking here is whether the API-Gateway should put the calling-user-id in the header (eg: "user context": "12345") or the query string /myapi/?calling-user-id=12345
I've tried both approaches and they both work. I'm wanting to know which approach makes the most sense to other developers.
Let's say that users X and Y authenticate themselves (separately) on a service's REST API, and that JSON web tokens are used for authorization between the client and server. We want to send user-specific data to each user.
Should we ask the user to specify who they are, or should the server detect it based on the authentication method (in this case the payload on the JWT)?
In other words -
Should the API have endpoints that look like this:
GET /:user/resource (for example) /user_x/resource used by user X and /user_y/resource used by Y,
or would it be better to have
GET /resource and then, in the route handler, check the user id (as part of the JWT payload) return data based on the user id?
I'm not sure which of these (if either) is the best approach, or if there might be another way to do it, such as using query strings. It would be great to hear any opinions about this.
Thanks.
The server can identify the user based on either a session cookie, or an access-token. In your case, if you use a JWT, the user-information is usually already included in the token.
So the server should just fetch the information out of this token.
Just make sure, that you check the tokens signature on the backend.
Otherwise, an attacker could just modify the JWT and send a different user-id to the server.
I am currently using Openiddict, Identity and Entity Framework to manage my users and assign Bearer tokens to users to protect my API.
My infrastructure is currently using ASP.NET Core Web API in the back end and a separate React application in the front end. The React application makes HTTP calls to my API to retrieve it's data. There is no server side HTML rendering at all in the back end.
Everything works as I need it to for the most part. I can register users and retrieve tokens from the API. These tokens are included in my HTTP call in the Authorization header. My AuthorizationController uses this: https://github.com/openiddict/openiddict-samples/blob/dev/samples/PasswordFlow/AuthorizationServer/Controllers/AuthorizationController.cs with a few minor tweaks. My Startup.cs also uses almost exactly this https://github.com/openiddict/openiddict-samples/blob/dev/samples/PasswordFlow/AuthorizationServer/Startup.cs
In some instances, I need to make API calls to the endpoints that are specific to the user. For instance, if I need to know if a user has voted on a comment or not. Instead of passing along the users ID in a query string to get the user details, I would like to use the Bearer token I received that they use to make the API call for that endpoint. I am not sure how to do this though.
In some research I have done it looks like some samples use ASP.NET Core MVC as opposed to the API to retrieve the user with the User variable as seen here https://github.com/openiddict/openiddict-samples/blob/dev/samples/PasswordFlow/AuthorizationServer/Controllers/ResourceController.cs#L20-L31 however this seems not to apply to my infrastructure.
My question is how do I look up a user based on the Bearer token passed to the API to look up a users details from my database? I am assuming that all of the tokens passed out by the API are assigned to that specific user, right? If that's the case it should be easy to look them up based on the Bearer token.
The question is: How with Openiddict can you look up a user based on the token that was assigned to them for API calls? I need to get the user details before anything else can be done with the application first. Is there something baked internally or do I have to write my own support for this?
When you create an AuthenticationTicket in your authorization controller (which is later used by OpenIddict to generate an access token), you have to add a sub claim that corresponds to the subject/entity represented by the access token.
Assuming you use the user identifier as the sub claim, you can easily extract it from your API endpoints using User.FindFirst(OpenIdConnectConstants.Claims.Subject)?.Value and use it to make your DB lookup.
I know this is not the first time the topic is treated in StackOverflow, however, I have some questions I couldn't find an answer to or other questions have opposed answers.
I am doing a rather simple REST API (Silex-PHP) to be consumed initially by just one SPA (backbone app). I don't want to comment all the several authentication methods in this question as that topic is already fully covered on SO. I'll basically create a token for each user, and this token will be attached in every request that requires authentication by the SPA. All the SPA-Server transactions will run under HTTPS. For now, my decision is that the token doesn't expire. Tokens that expire/tokens per session are not complying with the statelessness of REST, right? I understand there's a lot of room for security improvement but that's my scope for now.
I have a model for Tokens, and thus a table in the database for tokens with a FK to user_id. By this I mean the token is not part of my user model.
REGISTER
I have a POST /users (requires no authentication) that creates a user in the database and returns the new user. This complies with the one request one resource rule. However, this brings me certain doubts:
My idea is that at the time to create a new user, create a new token for the user, to immediately return it with the Response, and thus, improving the UX. The user will immediately be able to start using the web app. However, returning the token for such response would break the rule of returning just the resource. Should I instead make two requests together? One to create the user and one to retrieve the token without the user needing to reenter credentials?
If I decided to return the token together with the user, then I believe POST /users would be confusing for the API consumer, and then something like POST /auth/register appears. Once more, I dislike this idea because involves a verb. I really like the simplicity offered in this answer. But then again, I'd need to do two requests together, a POST /users and a POST /tokens. How wrong is it to do two requests together and also, how would I exactly send the relevant information for the token to be attached to a certain user if both requests are sent together?
For now my flow works like follows:
1. Register form makes a POST /users request
2. Server creates a new user and a new token, returns both in the response (break REST rule)
3. Client now attaches token to every Request that needs Authorization
The token never expires, preserving REST statelessness.
EMAIL VALIDATION
Most of the current webapps require email validation without breaking the UX for the users, i.e the users can immediately use the webapp after registering. On the other side, if I return the token with the register request as suggested above, users will immediately have access to every resource without validating emails.
Normally I'd go for the following workflow:
1. Register form sends POST /users request.
2. Server creates a new user with validated_email set to false and stores an email_validation_token. Additionally, the server sends an email generating an URL that contains the email_validation_token.
3. The user clicks on the URL that makes a request: For example POST /users/email_validation/{email_validation_token}
4. Server validates email, sets validated_email to true, generates a token and returns it in the response, redirecting the user to his home page at the same time.
This looks overcomplicated and totally ruins the UX. How'd you go about it?
LOGIN
This is quite simple, for now I am doing it this way so please correct me if wrong:
1. User fills a log in form which makes a request to POST /login sending Basic Auth credentials.
2. Server checks Basic Auth credentials and returns token for the given user.
3. Web app attached the given token to every future request.
login is a verb and thus breaks a REST rule, everyone seems to agree on doing it this way though.
LOGOUT
Why does everyone seem to need a /auth/logout endpoint? From my point of view clicking on "logout" in the web app should basically remove the token from the application and not send it in further requests. The server plays no role in this.
As it is possible that the token is kept in localStorage to prevent losing the token on a possible page refresh, logout would also imply removing the token from the localStorage. But still, this doesn't affect the server. I understand people who need to have a POST /logout are basically working with session tokens, which again break the statelessness of REST.
REMEMBER ME
I understand the remember me basically refers to saving the returned token to the localStorage or not in my case. Is this right?
If you'd recommend any further reading on this topic I'd very much appreciate it. Thanks!
REGISTER
Tokens that expire/tokens per session are not complying with the statelessness of REST, right?
No, there's nothing wrong with that. Many HTTP authentication schemes do have expiring tokens. OAuth2 is super popular for REST services, and many OAuth2 implementations force the client to refresh the access token from time to time.
My idea is that at the time to create a new user, create a new token for the user, to immediately return it with the Response, and thus, improving the UX. The user will immediately be able to start using the web app. However, returning the token for such response would break the rule of returning just the resource. Should I instead make two requests together? One to create the user and one to retrieve the token without the user needing to reenter credentials?
Typically, if you create a new resource following REST best practices, you don't return something in response to a POST like this. Doing this would make the call more RPC-like, so I would agree with you here... it's not perfectly RESTful. I'll offer two solutions to this:
Ignore this, break the best practices. Maybe it's for the best in this case, and making exceptions if they make a lot more sense is sometimes the best thing to do (after careful consideration).
If you want be more RESTful, I'll offer an alternative.
Lets assume you want to use OAuth2 (not a bad idea!). The OAuth2 API is not really RESTful for a number of reasons. I'm my mind it is still better to use a well-defined authentication API, over rolling your own for the sake of being RESTful.
That still leaves you with the problem of creating a user on your API, and in response to this (POST) call, returning a secret which can be used as an access/refresh token.
My alternative is as follows:
You don't need to have a user in order to start a session.
What you can do instead is start the session before you create the user. This guarantees that for any future call, you know you are talking to the same client.
If you start your OAuth2 process and receive your access/refresh token, you can simply do an authenticated POST request on /users. What this means is that your system needs to be aware of 2 types of authenticated users:
Users that logged in with a username/password (`grant_type = passsword1).
Users that logged in 'anonymously' and intend to create a user after the fact. (grant_type = client_credentials).
Once the user is created, you can assign your previously anonymous session with the newly created user entity, thus you don't need to do any access/refresh token exchanges after creation.
EMAIL VALIDATION
Both your suggestions to either:
Prevent the user from using the application until email validation is completed.
Allow the user to use the application immediately
Are done by applications. Which one is more appropriate really depends on your application and what's best for you. Is there any risk associated with a user starting to use an account with an email they don't own? If no, then maybe it's fine to allow the user in right away.
Here's an example where you don't want to do this: Say if the email address is used by other members of your system to add a user as a friend, the email address is a type of identity. If you don't force users to validate their emails, it means I can act on behalf of someone with a different email address. This is similar to being able to receive invitations, etc. Is this an attack vector? Then you might want to consider blocking the user from using the application until the email is validated.
You might also consider only blocking certain features in your application for which the email address might be sensitive. In the previous example, you could prevent people from seeing invitations from other users until the email is validated.
There's no right answer here, it just depends on how you intend to use the email address.
LOGIN
Please just use OAuth2. The flow you describe is already fairly close to how OAuth2 works. Take it one step further an actually use OAuth2. It's pretty great and once you get over the initial hurdle of understanding the protocol, you'll find that it's easier than you thought and fairly straightforward to just implement the bits you specifically need for your API.
Most of the PHP OAuth2 server implementations are not great. They do too much and are somewhat hard to integrate with. Rolling your own is not that hard and you're already fairly close to building something similar.
LOGOUT
The two reasons you might want a logout endpoint are:
If you use cookie/session based authentication and want to tell the server to forget the session. It sounds like this is not an issue for you.
If you want to tell the server to expire the access/refresh token earlier. Yes, you can just remove them from localstorage, and that might be good enough. Forcing to expire them server-side might give you that little extra confidence. What if someone was able to MITM your browser and now has access to your tokens? I might want to quickly logout and expire all existing tokens. It's an edge case, and I personally have never done this, but that could be a reason why you would want it.
REMEMBER ME
Yea, implementing "remember me" with local storage sounds like a good idea.
I originally took the /LOGON and /LOGOUT approach. I'm starting to explore /PRESENCE. It seems it would help me combine both knowing someone's status and authentication.
0 = Offline
1 = Available
2 = Busy
Going from Offline to anything else should include initial validation (aka require username/password). You could use PATCH or PUT for this (depending how you see it).
You are right, SESSION is not allowed in REST, hence there is no need to login or logout in REST service and /login, /logout are not nouns.
For authentication you could use
Basic authentication over SSL
Digest authentication
OAuth 2
HMAC, etc.
I prefer to use PUBLIC KEY and PRIVATE KEY [HMAC]
Private key will never be transmitted over web and I don't care about public key. The public key will be used to make the user specific actions [Who is holding the api key]
Private key will be know by client app and the server. The private key will be used to create signature. You generate a signature token using private key and add the key into the header. The server will also generate the signature and validate the request for handshake.
Authorization: Token 9944b09199c62bcf9418ad846dd0e4bbdfc6ee4b
Now how you will get private key? you have to do it manually like you put facebook, twitter or google api key on you app.
However, in some case you can also return [not recommended] the key only for once like Amazon S3 does. They provide "AWS secret access key" at the registration response.
I have developed a REST/JSON API. The API exposes a lot of features. The API will be consumed by applications we design internally (mobile apps and web apps), by applications designed by our resellers and by applications designed by businesses. I am looking at securing the application by implementing authentication and authorization. I have 'googled' a lot but my research has left me with more questions than answers.
Our internal application will be used by end users registered on the application. In essence, our application is just a client taking request from the end user, taking it to the REST API and retrieving the data for the end user. Our internal application should be able to perform all the operations exposed by the REST API. What is the best way to handle user login on our internal application? HTTP Basic over SSL or OAuth?
Our reseller applications can create users like they own the users but ultimately the user details get stored in our database. The reseller application will just act as a client taking request from the user and fetching user data. Our resellers applications should only be restricted to some operations of the REST API. What security mechanism will I use to implement this kind of authorization and user login?
I hope my question is clear. Thanks for the help.
From what I understood in reading this there are two parts to your question:
What is the best authentication method for my API?
I recently developed an authentication system for an API that was modelled on OAuth but didn't have every single one of their specifications. The system was basically the same as what Amazon use for their API. [This article]1 is very helpful if you want a secure API authentication model without having to use OAuth.
The model uses these principles:
Authentication data will be passed with every request to the API server
Requests will include a Unix timestamp from when it was generated
The entire request (including the timestamp) will have an HMAC hash generated and sent alongside the rest of the data. The hash is generated using a private key that only the API server and the API client know.
The API takes the data (including the timestamp), generates an HMAC hash using the private key for that user (identified by a user ID, user name, public API key, whatever) and compares it to the hash sent with the request. If this was successful, regular authentication proceeds and the request is processed. Note: the API will check the timestamp and compare it to its own to make sure the request has occured within a valid timeframe of, for example, 30 seconds, 5 minutes, 10 minutes, etc.
Of course, you can use regular HTTP authentication over SSL/HTTPS also, but I find this way to be very good because you achieve a high level of security without needing to implement every aspect of the OAuth protocol.
How you authenticate is up to you essentially. I prefer to go with methods employed by large, trustworthy organisations (such as Amazon). I personally didn't want to go the whole hog with OAuth like Twitter, Facebook etc.
How should I allow different users to access different endpoints in my API?
You should have an internal map in your API server which contains records allowing or denying specific API accounts from accessing certain endpoints. In my API server I decided that all endpoints would be "allow" by default, and I would specify which accounts would not be able to access certain endpoints.
You could also set up different groups or types of API access accounts which could have group permissions like this.
My suggestion would be to [read this article]2 twice, or three times, then read it again. Then, implement the methods suggested within.
Personally, I think the best method for ensuring as much security as possible is to restrict absolutely everything in regards to the request to be within a set of boundaries that you define, e.g. I want this endpoint to only be accessible by GET HTTP requests (all other HTTP methods will throw an error), up to 3 times daily per account, within a 30 second timeframe of request to server, only allow a narrow range of data to be returned, etc.
Limiting the HTTP method is very important to reduce the risk of your API doing things it shouldn't, especially with a RESTful API as endpoints can be used to do multiple things depending on the request method. You can even set your permissions for each API account to restrict certain methods on each endpoint, e.g. API user xxx can GET information from an endpoint but cannot POST, PUT, PATCH etc, or API user xxx2 can POST data but cannot GET any, etc.
[EDIT] 1 and 2: www.thebuzzmedia.com/designing-a-secure-rest-api-without-oauth-authentication/ (not completely removing the link but keeping the url unlinked as it no longer works/redirects to random sites)