I am working on the ASP.NET MVC 5 web application. It has only one layer which contains views as well as business logic/operations. Business logic is logically separated from UI but it is not behind a separate web service/API layer.
Now when I use OIDC and OAuth2.0 for my application, there is no separate Resource Server, so to say. Because Client itself has all the Resources I want to have access to.
I am using Authorization Code Flow for authentication & authorization.
Questions:
Does access token have any role in this case? If yes, what?
How am I going to practically use the access token? Since the client itself is the resource server, there is nothing to which I need to send access token to.
I guess you get an ID token which contains all the information you need for authentication of a user. If not, you can use the access token to get the user info. If this is all the information you need, then the access token is not needed anymore. This happens, because OAuth2 is a permission delegation protocol, not an authentication protocol in a first place.
When you have the user info, you can implement between the browser and your ASP.NET backend in any way. You can take a look at the OAuth 2.0 for Browser-Based Apps RFC.
In this case you should use Client Credential flow instead of Authorization Code flow.
In Client Credential flow, your application would send your client id & client secret to Authorization Endpoint directly and asking for access token. Authorization Code is not needed in Client Credential flow. Details as below
An authorization code flow typically need your client redirect
resource owner to authorization endpoint and get a authorization
code from authorization endpoint, client than uses this code to get
access token, at the end of the day client uses access token to
access protected resource.
In Client Crendential flow. your client app is actually the owner of
your resource. So no need to asking for a authorization code. direct
uses its own client credential to get access token from
authorization endpoint and use that access token to access protected
resource(Resource server)
So, I'm developing an API using slim/slim and league/oauth2-server to manage the OAuth2 connection. OAuth2 will be useful because I will need to use Client Credentials grant between services.
Then, I'm also developing an hybrid app with React Native. This app will requires user login by using e-mail and password or connecting with another services (such as Facebook, Google, Twitter, etc).
And I'm confused about what OAuth2 flow to use for this case. Across the web are a lot of articles saying that Resource Owner Password Credentials is not safe anymore, and we should use instead Authentication Code with PKCE.
But I can't discover or understand how to apply Authentication Code with PKCE in a first party app, because all documentation talks about you will need the uses a browser to get authentication code in redirect_uri.
The flow I imagine is something like that:
User open the app, then insert your credentials username and password;
This screen will connect to API /request_token URI sending { 'grant_type': 'password', 'username': username, 'password': password, 'client_id': CLIENT_ID }, considering it as a public app we can't send client_secret;
The API validates credentials and returns some data such as { "access_token": access_token, "token_type": "JWT", "expires_in": LIFE_SPAN }, here we will use JWT to gerenate the access_token based in public/private key;
Authentication done, the app will store the access_token while it's alive and when it expires will do the flow to refresh_token.
My question: is it safe? Scott Brady did some "aggressive" article talking it's NEVER safe.
How apps does this things? When I use Instagram app, for example, they own the app and the API, I don't need a browser in the User Experience flow. Are modern apps using "Resource Owner Password Credentials" or "Authentication Code with PKCE"? There is a away to avoid insert browser in the flow while using "Authentication Code with PKCE"?
[EDIT] Possible Solution
As Gary Archer said "Auth Code flow with PKCE is recommended - along with logging on via the system browser", but we are not talking about grant permissions to access users data or third-party apps.
As a designer I don't agree that loggin in the first-party app owned by the same API owner requires a browser this is the not the User Experience we are looking for. And all apps we see such as Instagram, Facebook, Uber... we just put your username and password and we have access to your account.
What I will do is create a custom version of Authentication Code with PKCE removing the required_uri.
[EDIT:2] The New Flow
After a lot of search, I found some answers I think was interesting to adapt. As above, I removed redirect_url from flow. Look:
The flow starts in a login screen, when user give your credentials;
Client generates a code_verifier then hashes code_verifier to code_challenge and sends it to Authorization Server with following parameters:
response_type=code : indicates that your server expects to receive an authorization code.
client_id=xxxx : the client id.
client_integrity=xxxx : app integrity check for first-party app.
code_challenge=xxxx : the code challenge generated as previously described.
code_challenge_method=S256 : either plain or S256, depending on whether the challenge is the plain verifier string or the SHA256 hash of the string. If this parameter is omitted, the server will assume plain.
username=xxxx : username to authenticate.
password=xxxx : hashed version of password.
state=xxxx : a random string generated by your application (CSRF protection).
Authorization Server will validates user authentication, stores code_challenge and return the authorization_code with a client_token;
After receive the aauthorization_code and client_token, Client saves the client_token and immediately send authorization_code back to Authorization Server with following parameters:
grant_type=authorization_code : ndicates the grant type of this token request.
code=xxxx : the client will send the authorization code it obtained.
client_id=xxxx : the client id.
code_verifier=xxxx : the code verifier for the PKCE request, that the client originally generated before the authorization request.
Authorization Server will validates all data and, if everything is right, will return the access_token;
Client will set Authorization header with the access_token and always send client_token to every request, it will be only accepted with both values are right;
If access_token expires, then Client will do a request to refresh access_token and get a new one.
Now, I will reproduce this logic to PHP language. If everything goes right and I hope it does, I will be back with definitive answer.
[EDIT] Clarifications
I'm using OAuth2 to user connect with your third-party accounts (Google, Facebook, etc). But user also can log to a local account in my database. For this case, user doesn't need to grant anything at all. So, no makes sense send user to a browser to him does your login.
I wondering if, to this case, local accounts, we can use Resource Owner Password Credentials or it's more safe Authentication Code with PKCE (we already conclude it's a better approuch). But Authentication Code with PKCE requires redirect_uri, do I need uses this redirection to log users into a local account where they don't need to grant access?
Let's go then. After a lot research, I found some approaches that I will apply and may work correctly. So, first of all, here is the challenges:
You must never trust in clients running in client side. There's a lot of concerns about, your applications can be decomplied, modified, the users devices can be with a malware or connection may suffer with a man in the middle attacking (MITM)...
An API Server, even using OAuth2, will be able to only identify WHO is accessing the resources, but not WHAT is accessing. Therefore, any sensitive information will be dangerous, anything can steal it and uses it.
Resource Owner Password Credentials makes part of OAuth2 protocol for authorize resource owner to access your resources. So, it doesn't make part of authentication process and you will your ruin if you treat it like that;
By using ROPC grant type there is no way to know if resource owner is really making that request, what make "easy" a phishing attack. Reminds about "you know WHO and not WHAT". For last, this kind of grant makes easy for whatever thing assumes the user identity;
This grant type also goes against OAuth2 propourse, since OAuth seeks to avoid the password use to access resources. That why many people say to don't use it;
For reinforce, it's important to highlight ROPC is not authenticating user, but it just authorizing him to access the resource server.
And yes, ROPC allows for refresh tokens, but there are two issues: first, client needs resupply credentials each time needed to get a new token; second, if using a long-term access code, then things get more dangerous.
To prevent a malicious thing from arbitrarily using user credentials there are access tokens. They replace passwords and needed to be refreshed in short amount of time. That's why they are so much better than HTTP Basic Authentication.
That's why is recommended to use in modern apps the Authentication Code with PKCE, it provides all features and benefits of using OAuth2 protocol. But, here cames a long discussion and, even, problem for developer community:
To get an Authentication Code some user needs to make your login in a browser, grant access, redirect back to client and, soon, client will receive a code to exchange for an access token.
This scenario works good and NEEDS to be used for third-party apps. But, what if it is a first-party app? When you own the database with user data and you own the "trusted" app, redirect user doesn't make any sense. Right?
At this moment, my question is: how can I use the AuthCode (PKCE) flow without redirect user? And, again, it's important to highlight that talking about OAuth2 protocol is always the same that "to grant client to access resource server" (authorization, not authentication).
So the real question is: why Authorization Code needs a redirection at all? Then, I came with the following answer:
This flow requires to know client credentials and user consensus to turn back an authorization code.
That's why I was wrong in my edits. There's no change needed in OAuth2 protocol (sorry me for think different). For this reason, what OAuth2 needs is a authorization mediator, above your layer. Thus, the authorization code not will turn back to client, but to authorization mediator that, finally, will return it to client. Makes sense?
How it gonna work? Well, will be need 4 different "cores":
Authentication Server: will be responsible to authenticate user credentials and client identity. The main objective is to prove "WHO is the user and WHAT is connecting to get authentication";
Authorization Mediator (one layer above OAuth2): will validate client unique identity to ensure client/user is "know" and can get an access token;
Authorization Server: makes part of OAuth2 implementation, nothing change. Will authorize a client to get your authorization code, access tokens an refresh tokens;
Resource Server: will allow access resources through an access token.
And, then, security techniques we may consider:
API Key: each application (client) will have your own API Key with permissions scopes associated with those keys. By using it, you can gather basic statistics about API usage. Most API services use statistics to enforce rate limits per application to provide different tiers of service or reject suspiciously high frequency calling patterns;
Mutual SSL Authentication: by using this technique client and server exchange and verify each other's public keys. Once the keys are verified, the client and server negotiate a shared secret, a message authentication code (MAC) and encryption algorithms;
HMAC: API Key will be separeted into an ID and a shared secret. Then, as before, the ID is passed with each HTTP request, but the shared secret is used to sign, validates and/or encrypt the information in transit. The client and server will exchange the shared secret with algorithm such as HMAC SHA-256;
Protecting code application: using code obfuscators will make harder to locate and extract sensitive data from app, such as secret shared, api keys, public keys...
Handle user credentials: providing a simple method to user login and prove your identity. After insert valid credentials, server can return a user token (JWT) and emulates a user session with this.
Let's look at flow:
Part one: autheticating user and client;
User will type your credentials and be asked to prove your identity using your e-mail or mobile number, after Client will send user credentials (such as { email, mobile_number, hash ( password ), verification_method }) to Authentication Server route /login;
Authentication Server will validate user credentials and send a one-time password to user confirm your identity (for e-mail or mobile number as choose by user);
Then, user will insert the OTP received and client will send back to Authentication Server route /login-otp including the verification method (such as { otp, verification_method });
At the end, Authentication Server will return a { hash ( shared_secret ) } to be used soon.
Part two: authorizing API access;
When receive shared_secret Client will stores securely at mobile app, then it will ask for a authorization code using PKCE calling /auth with { response_type, client_id, scope, state, code_challenge, code_challenge_method }, Authorization Server will validate credentials and return an authorization code with no redirects;
Later, Client will exchange received code to an access token accessing /token, but it will need to send some extra data: { payload: { grant_type, code, client_id, code_verifier }, timestamp, hash ( some_user_data + timestamp + shared_secret ) };
Authorization Mediator will receive this request and validate trying to generate the same hash generated by user. And redirect all data to Authorization Server that will validate client_id, code and code_verifier responding with an access token;
This new access_token will return to Authorization Mediator and, after, to client granting access to API resources.
Part three: accessing resource server;
Client will each time needs send a call to API /api containing the Authorization header and some extradata with { timestamp, hash ( some_user_data + timestamp + shared_secret ) };
Authorization Mediator will validates the shared_secret hashes, call Resource Server validating access_token and return data.
Part four: refreshing access token;
After access token expires, Client will send a call to /refresh-token containing the Authorization header and some extradata with { payload: { grant_type, refresh_token, client_id, scope }, timestamp, hash ( some_user_data + timestamp + shared_secret ) };
Authorization Mediator will validates the shared_secret hashes, call Authorization Server and return a new fresh token access.
A visual image for this flow:
I don't think it is a perfect strategy, but it replaces Resource Owner Password Credentials to Authentication Code with PKCE and gives some extra security techniques. It's way better then a single and simple authentication method, preserves the OAuth2 protocol and mantaein a lit bit more hard to compromise user data.
Some references and support:
How do popular apps authenticate user requests from their mobile app to their server?
Why does your mobile app need an API key?
Mobile API Security Techniques
Secure Yet Simple Authentication System for Mobile Applications: Shared Secret Based Hash Authentication
Auth Code flow with PKCE is recommended - along with logging on via the system browser. Also the AppAuth pattern is recommended.
https://curity.io/resources/develop/sso/sso-for-mobile-apps-with-openid-connect/
It is tricky and time consuming to implement though - so you need to think about it - sometimes using a cheaper option is good enough. Depends on the sensitivity of data being exposed.
If it helps here are some notes for an Android demo app of mine, which also focuses on usability - and links to a code sample you can run:
https://authguidance.com/2019/09/13/android-code-sample-overview/
First of all, do not invent a OAuth grant simply because you need to adopt it in your application. It will make tings complex to maintain.
In your scenario you need to provide social login (ex:- Login via Google, facebook). This of course a desired functionality one must support. But it doesn't limit you from obtaining end user credentials through a custom registration process. There are many reasons for this, for example not everyone use social media or a Google account. And sometims people prefer to register than sharing user identifier of some other service (yes, this is the opposite end of social login).
So go ahead, provide social login. Store user identifiers when first login through external identity server (ex:- Google). But also, have a good old registration step with password and an email.
I have:
Spring boot client application with some public endpoints and private endpoints which require #PreAuthorize("#oauth2.hasScope('resource.read')") for example
I have a external authorization server: Cloudfoundry UAA
I have a external OIDC provider linked to UAA I can use that to authenticate a person, I receive a Person_ID from the ID_Token from that external OIDC provider
Now I need to change UAA core code to implement my logic of using that Person_ID and searching for equivalent user from LDAP which shares the same Person_ID and then I will need to add it's usergroups to the token for the client. (I have done it currently in the /userinfo endpoint)
So I have done this logic in the /userinfo endpoint, when client receives a access token (From client, redirected to UAA, from UAA to OIDC for AUTH, then back again for the token and then this token is sent to client, now client can take the token and ask for the /userinfo which will then have it's user roles)
Is this bad logic? Should I add the LDAP implementation(step4) inside the access token already somehow?
Really, as is often the case with design questions, it depends.
The key to remember is that OIDC and its associated id_token are for authentication. It's common for the /userinfo response to state claims about who the user is. Part of the user's identity might be their role.
OAuth and its associated access_token, on the other hand, are for authorization. It's common for the access token to state claims about what the client is authorized to do. What a client might be able to do may be different than the user's role.
Think about what decisions this client will need to make. It may be able to make choices like which of its pages it can show, based on the roles that it inferred from the /userinfo response.
Think about what this client will communicate with. Maybe it will communicate with a resource server. If the client passes the access_token obtained during login, then that token should indicate what the client is authorized to do.
Here is my plan (authorization code flow) of implementing such login/register logic. (The third-party only provided the OAuth2 API)
First the SPA frontend will send a GET request to the third-party
GET https://www.example.com/oauth2
client_id=dummyclient
redirect_uri=https://mysite/callback
response_type=code
scope=openid
Then if the user agree to give his/her openid to mysite then the fronend will get a 301 HTTP response.
---> 301 https://mysite/callback?code=dummycode
Then the browser will redirect the page to mysite/callback and it will reload SPA and expose the code in URL which can be captured by the SPA then it will send the code to the real backend callback.
GET https://mysite/api/real-callback?code=dummycode
When the backend get the code, it will send the code to the third-party to exchange an access_token. When the backend get the access_token, it will fire an API request to get the user's openid then decide whether to let the user login or register as a new user. At last it will give back a HTTP response to our SPA frontend which contains the access_token in my OAuth2 system or a 401 unauthorized response.
So my question is how to prove that the real callback is invoked by my own clients (Because if some attacker get my frontend embedded client_id then he can fake the OAuth2 request and phishing the user to agree. After that the attacker will get a valid code then he send back the code to my real callback. Finally, he will get the user's access_token in my system.) How can I use OAuth2 to do authentication without the end user's providing additional information like password.
I would suggest you to change the OAuth2 flow to Implicit and ask for both access_token and id_token (OpenID Connect). Your SPA will get the tokens, send the ID token to your backend, which can use it to decide whether it's possible to create such user. The SPA can use the access token to call protected resources.
This way,
only the SPA will be an OAuth2 client - tokens will not be used by two applications (SPA and backend),
you will have just one redirect URI,
you will not need to transfer tokens from the backend to the SPA.
Update: Without OpenID Connect
If you cannot use the id_token, you could send the access_token to your backend and the backend can get the user's username by sending to token to the Introspection endpoint https://www.rfc-editor.org/rfc/rfc7662 (from the response username attribute). The username attribute is optional. Your OAuth2 server may return even more info (such as name and email).
This Introspection endpoint requires authentication, so to use it, your backend will have to be a registered OAuth2 client with its own client_id and a secret.
I am writing a REST API to be consumed by our internal applications. I need to login and logout users of the identity server using code grant via http requests
presentation
I need to know how to call the following endpoints:
/authorize (invoked from server-side)
/accesstoken (invoked from server-side)
/login
/logout
CASE:
Our company has many applications. I want one point of authentication which will happen in their company-x account like how you only need to login to atlassian account to access jira and confluence cloud. The REST API I'm working is for our front-end developers (as of now).
presentation
I cannot simply let the user login to WSO2 IS since they only need a module where they can manage their company-x profile and other basic stuffs. By this I think I have 2 options:
Customize WSO2 Identity Server UI and permissions. But the problem is, I still need an endpoint to get that id_token. I am also not sure if this is the right approach.
Know how to call /authorize, /accesstoken, /login and /logout endpoint and write my own minimal required UI and provide an endpoint that will respond the id_token
How about having a basic login page on front-end and use request path authenticator to get the authorization code/id_token.
Basically what this means is instead of redirecting the user to IS login page you can extract the username and password from the basic login page you created and send the authorization grant request along with the credentials.
so your authorization code request will be:
https://localhost:9443/oauth2/authorize?response_type=code&client_id=JqB4NGZLMC6L3n4jz094FMls2Joa&redirect_uri=https://localhost/callback&scope=openid§oken=<sec_token>
sec_token = base64encode(username:password)
You need to add basic-auth request path authenticator in your Service Provider configurations. This request should return you an authorization code. If you want an id_token simply use the implicit flow with request path authentication.
If you use code grant type, there will be a browser redirection from /authorize to /login. I don't think you can handle that by a REST call. (You might be able to handle that by calling url in location header of each 302 response. But I don't think it's a nice way to do this.) If you want to develop a REST API, I think password grant type will be more suitable.