I have to create a way to keep the session authentication from application A to application B, but I can´t use:
SSO
POST calls
and, we know that GET is not a good choice, but I´ll need to use it. So, I think to use something like "public keys", what you think about this approach?
I think in:
User do authentication in application A.
Into application A, have a link to application B; User click on this link
Application A open application B page sending a "public key" (database persistent authentication key?)
Application B validate this key and authorize or not the user.
In step 3, rather than thinking of a "public key", think of a "session token". Specifically, A redirects to B with
http://b.application.com?token=123-3-2-1-3-2-2-1-2-32-3-5-2-4-5245
Tokens should be unique and short-living.
B then contacts A directly and asks about the identity behind the session token:
http://a.application.com/userservice/getuser/123-3-2-1-3-2-2-1-2-32-3-5-2-4-5245
Because B contacts A directly, there is no way for users to forge invalid tokens - a random token just points to non-existing session at A.
Related
I am using Identityserver4 for AuthZ and AuthN and trying to understand the purpose of scopes for a webapi
I am implementing a first party application an internal application which will works in intranet. so there will be no consent page.
image : application architecture
I have 3 users
User X : who can perform read and write operation on Web API ‘A’ Only
User Y : who can perform read and write operation on Web API ‘B’ Only
User Z : who can perform read and write operation on both Web API ‘A’ and ‘B’
Since all the user will log in using the ‘Angular front end’. In the front at the time of login the scopes requested must be like below
{
response: code
scopes : ‘openid A:read A:write B:read B:write’
}
As I said earlier, I am using Identityserver4 once the user successful logins the client will receive Id_token and access_token.
I understood from different article that api will check for the scope to provide access to an operation like read and write. So,
If User X logs in, access_token should contain scope only A:read, A:write
If User Y logs in, access_token should contain scope only B:read, B:write
If User Z logs in, access_token should contain scope only A:read, A:write, B:read, B:write
Since ‘Angular front UI’ is same for all the 3 users (X, Y, Z) in my case.
Client will request all the scopes (A:read, A:write, B:read, B:write) is this correct ?
Do I need to write any custom logic when access_token is getting generated, its should include only scope that user is entitled too?
If I have to write this custom logic which interface I need to implement. is it IProfileService?. i have to use something like role to find out the scopes?
Lastly, in other word, scopes for an web api is nothing but permissions am I right?
In IdentityServer I would create one ApiScope (perhaps named ApiAccess). Then I would create two ApiResources, one for each API and associate them with the ApiScope created earlier.
Then have a UserClaim (perhaps named access) associated with the ApiScope, that contains the particular users access (read or write).
the value for the access claim is then retrieved from the user database.
Also, do see my answer here for a clarification between ApiSope, ApiResources and IdentityResources.
To complement this answer, I write a blog post that goes into more detail about this topic:
IdentityServer – IdentityResource vs. ApiResource vs. ApiScope
I'm working on a client-server application using WCF. The first client will be a desktop app (WPF) but I plan to add Xamarin (Android and iOS) and web client. I want this to be an internet service, and to potentially support a large number of clients, so I'm using http, a stateless service to conserve server resources.
I am having difficulties implementing authentication logic.
I found this great example that implements forms authentication:
http://www.dotnetspeak.com/wcf/securing-wcf-with-forms-authentication/
It allows me to handle authentication how I want - compare username and password against the database, create an authentication cookie and return it. Subsequent calls using this cookie will be authenticated automatically.
But the problem is, I don't know which user called the service. If GetMyData() is called by user1, I want to make sure he only gets his own data. I obviously don't want to have the client send their ID separately with each request, because that can be easily tampered with - just switch "user1" for "user2" and hey presto, you're getting someone else's data.
I can get to the authentication cookie inside the service method by calling
WebOperationContext.Current.IncomingRequest.Headers[HttpRequestHeader.Cookie]
(I can also see there's one other header called "Host")
The cookie is generated from a FormsAuthenticationTicket, which contains the username and password, but it's encrypted. I'm not sure whether it's possible for me to decrypt the cookie in my code, but I'm pretty sure it wouldn't be the correct approach. My method was called AFTER the underlying system authenticated the caller, so presumably the cookie was decrypted and the ticket was found to be valid. So why can't I get to the data?
Sadly, every article I've found only deals with authenticating the user, but nobody seems to care about which user is using the service afterwards, as long as he's authorized.
I suppose I could store the cookies server-side, along with mapping to the specific user, and find the user that way. But I want the service to be as stateless as possible for performance reasons. Also, this would involve doing fulltext matching on a 300 character long string - for every single request! Yikes!
It seems to me that what I need is a very common use case, so there must be a proper way to do it. I just can't seem to find it. Can anyone help me out?
If you have Forms authentication setup correctly then you can get the logged-in username via Thread.CurrentPrincipal.Identity.Name and send it to your service method for data access validation. Get the user id from username and validate ownership.
Thread.CurrentPrincipal.Identity.Name decrypts the cookie ticket and returns the logged-in username.
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.
This question has already be asked 20 times and i read a lot about it... but i need confirmation about something. I just want know if i understood good.
The first part is about definitions :
Identification : To identify the client, know who it is exactly.
Authorization : To allow access to some ressources. No identity here.
Authentication : Combine Identification and Authorization.
My first question is : Reasoning good or not ?
Then, my second part is about OAuth & OpenId :
At the beginning, for the basic implementation, OpenId is only for the Identification part and OAuth is for the Authorization part.
But now, after upgrading, the both tend towards an Authentication part.
For example, OAuth basically can just allow one application to access to another without the password or critical informations of the user through the network. It just do it one time and generate a token which can be revoke or refresh and need to be given for each request.
Now, with the basic implementation of OAuth, if S1 allow S2 to get users informations, i can access to these url : path_to_s1/api/users/foo - path_to_s1/api/users/bar and i will get the informations (email - contacts... for example) of the user foo when i will be on the first url and of the user bar when i will be on the second url. I just have here the Authorization and not the Identification. For the identification, i can for example implement an API Key or OpenId Connect on the top of OAuth.
My second question is : Reasoning good or not ?
Thank you in advance :)
If S1 gives S2 information based on a token, then S1 could have stored information about that token - e.g. the identity of the user. So using oauth for authorization does not mean you cannot have identity information about the user.
Is it possible to limit the users who can sign in with open id on my site. I have clients that I want to give access to a client area on my website. I don't want anyone with a open id to be able to login just my clients. Is this possible?
One way to do this would be to create a "sign up" form to validate the user. Part of the sign up process would be to associate your OpenID. You can then leave the newly created account in a "pending" mode to be approved by an admin. (note: if you have a different way of adding the clients, you would use that method.)
Basically you would create a profile for a user the same way you would in any other application, except you would replace the UserName / Password portion with OpenID.
OpenID is made for authentification, not for authorization. I am sure, you could make it work (*), however you must keep in mind that OpenID has not been made for this sort of task.
If you want to do it, you must probably restrict the set of allowed OpenID providers to prevent a malicious provider to hand faked/bogus identity URLs to your application (consumer).
(*) how, depends on where you want to enforce the restriction (web server, web framework, etc.)