I read something like this:
1-Once a user logs in, you can generate a token and store it in MySQL database and share the same token with the response of login API.
2-Store the token using shared-preferences.
3-When a user opens the app, check if the token exists if it does, then send the token with all the APIs inside the request header which requires the user to be logged in.
But what is the point of using token if i was keeping it in database.Eventually this token related with userid and with this userid everthing can be reachable.So I want to ask why should I use some token to keep user loged in instead of user email or something.
Using token is much more secure and useable. Storing just token more secure becase in case of leak, the token can be revoked or something. On the other side storing user's username and password is security risk. Also, most of the services use tokens on their API's and there is no username+pass authorization. For example whole OAuth2 concept is built on top of this. In short, tokens are much more secure and flexible.
Optimal usage of bearer token using as a set with an access token and refresh token. While you are passing access token on header while you are making HTTP request typically access token dies frequently especially when security is a prominent feature of the app, like banking apps. When a user makes an HTTP request and if the access token is dead then you should refresh it via another API call with the refresh token and return the same API call with the new access token.
I would like to ask little theoretically.
I have an angular6 + spring app that has its own client, app-specific client data.
These data can be divided into two groups
managment-data: Like client roles that allow client to visit different parts of app
client-data: personal settings, history of activities etc.
Because I would like to make login as user-friendly as possible, I would like to implement facebook login.
After user click "FB login button", facebook returns me some-user info and mainly a security token. How could I use this to securely communicate with my BE.
When someone sends request to BE, I need to be sure, that its the same person that logged in to facebook.
If I send this token as part of request, what stops possible attacker to somehow obtain token and then impersonate original user?
In what form I should send data I got from Facebook to my own server?
How should I work with token on server?
How can I validate its authenticity?
Thank you for answers
Filip Širc
You should look into the usage of OpenID Connect along with OAuth protocol. It allows you to authenticate the user to your client application (Angular6 + Spring app) to verify the user details.
When you are sending an access token to access a certain resource, you should avoid sending it as a request parameter. Usually it is encouraged to send it under the Authorization header of the request as a bearer token. However, if you want it to be extra secure, you could encode the token before sending so that it would be difficult to decode it and steal any valuable information.
Also, when you are sending sensitive information, it ise better to send them in the form of a JSON Web Token (JWT). You can use a third party library to create a jwt to include the information that need to be sent to the server. You can sign the jwt with your own signature which can be validated later. Refer https://www.rfc-editor.org/rfc/rfc7519 for detailed information about jwts.
You should use the claims in your access token to grant a user access to the resource you are protecting. Since most of the tokens are sent in the form of jwts, you can decode them and get check the necessary claims such as scopes, audience (client app), subject (user), etc.
Most importantly, you should validate the signature of the token sent from Facebook to make sure its an authentic one. For this, you have to get the public key details from Facebook's jwks endpoint and validate the signature using a third party library (auth0, nimbusds, etc.). Facebook's digital signature will be unique and this verification process is the best way to ensure the security. Also, you can check whether certain claims in the token match your expected values to validate the token. This can also be done through libraries such as ones mentioned above. Here's auth0 repo for you to get a general idea.
I want to make a Facebook batch call to read registered users walls.
As far as I know, I need to especify the user access token in the body of each call in batch. But with offline_access depreciation, I need to revalidate all users access token before use it.
So, if I am batching multiple calls, it makes no sense to revalidate each access token separatly (like discribed here: http://goo.gl/M3Jrr).
How can I revalidate those access token faster?
How can I re-validate those access token faster?
You can't. Once a user access token is expired, you need to capture this and get the user to engage with your app to refresh the access token.
Now I don't know why would you need to read your registered users walls in bulk which, depending on your motives, might be a violation of Facebook policies but I suppose in the response body of the batch call you should receive a clear error about an expired access token and hence, for example, add a flag in the DB for those (inactive) users to re-engage them later.
Why do you need both a "code" and a "token" in the Facebook OAuth2 authentication flow as described here: https://developers.facebook.com/docs/authentication/ ?
If you look at the OAuth dialog reference (https://developers.facebook.com/docs/reference/dialogs/oauth/), it seems like you only ever use the token to fetch information about the user, and if you specify the response_type parameter as token or code,token, then you get the token on the first time.
Why do you need to get a "code" and then use the code to get a "token" as opposed to getting the token directly?
I guess I'm misunderstanding something basic about how OAuth works, but it seems you avoid the request to https://graph.facebook.com/oauth/access_token entirely if you get the token the first time with the dialog.
Let us take a simple example to differentiate authentication code vs access token.
You as a user want to try a new Facebook app called Highjack.
So you click on the application and the Highjack app asks you to log into your Facebook account. When you are done, Facebook generates an authentication code for you.
This code is then passed to the Highjack server which uses its own FB client id, FB secret and your authentication code to get an access token.
In the above example the authentication code is confirming you as a user is a valid FB user. But the second steps says "you as a FB user is giving access to the Highjack app for certain resources".
If the Highjack app wanted implicit grant (i.e direct access token), then the access token would be visible to you also since it is being exchanged with the browser. This means you can now call all Facebook APIs on behalf of Highjack using the access token. (You can only use the access token to get your personal information but Facebook has no way of knowing who is calling their APIs.)
Since we have 2 parties (You and Highjack) authenticating with Facebook we have this 2 fold mechanism.
Borrowed shamelessly from Salesforce Documentation:
Authorization Code
An authorization code is a short-lived token representing the user's access grant, created by the authorization server and passed to the client application via the browser. The client application sends the authorization code to the authorization server to obtain an access token and, optionally, a refresh token.
Access Token
The access token is used by the client to make authenticated requests on behalf of the end user. It has a longer lifetime than the authorization code, typically on the order of minutes or hours. When the access token expires, attempts to use it will fail, and a new access token must be obtained via a refresh token.
From the OAuth 2.0 Spec:
The authorization code provides a few important security benefits
such as the ability to authenticate the client, and the transmission
of the access token directly to the client without passing it through
the resource owner's user-agent, potentially exposing it to others,
including the resource owner.
So, basically - the main reason is to limit the # of actors getting the access token.
"token" response is intended primarily for clients that live in the browser (e.g.: JavaScript client).
Answer) You need/want both the code and token for extra security.
According to Nate Barbettini we want the extra step of exchanging the authentication code for the access token, because the authentication code can be used in the front channel (less secure), and the access token can be used in the back channel (more secure).
Thus, the security benefit is that the access token isn't exposed to the browser, and thus cannot be intercepted/grabbed from a browser. We trust the web server more, which communicates via back channels. The access token, which is secret, can then remain on the web server, and not be exposed to the browser (i.e. front channels).
For more information, watch this fantastic video:
OAuth 2.0 and OpenID Connect (in plain English)
https://youtu.be/996OiexHze0?t=26m30s (Start 26 mins)
If you look at the flow of Authorization Code OAuth type, yes, there are actuary two steps:
<user_session_id, client_id> => authorization_code
<client_id, redirect_uri, authorization_code, client_secret> => access_token, refresh_token
In step1: the user tells the OAuth Server that "I want to auth this client (client_id) to access my resource. Here is my authentication (user_session_id or what else)"
In step2: the client (client_id) tells the OAuth server that "I've got the user the authorization (authorization_code), please give me an access token for later access. And this is my authentication (client_id & client_secret)"
You see, if we omit step 2, then there is no guarantee for client authentication. Any client can invoke step1 with a different client_id and get an access token for that client_id instead of its own. That's why we need step2.
If you really want to combine step1 and step2, you can do something like this:
<client_id, redirect_uri, client_secret> => access_token, refresh_token
We use this approach in our Open API Platform, and we haven't find any security problem yet.
BTW, there is actually an Implicit Grant type, that is:
<client_id, redirect_uri> => access_token, refresh_token
It is generally applicable to client only application which have no server backend. In that case, the OAuth server must ensure that the redirect URI belongs to that client (same with the register redirect_uri, for example).
The mix-up came because the user on behalf of himself and not the client app authenticate against the authorization server (i.e. facebook).
Its much simple to secure the client app (with https) then the user-agent (browser).
Here is the original formulation from IETF-oauth (https://datatracker.ietf.org/doc/html/draft-ietf-oauth-v2-threatmodel-08#section-3.4):
3.4. Authorization Code
An authorization code represents the intermediate result of a
successful end-user authorization process and is used by the client
to obtain access and refresh token. Authorization codes are sent to
the client's redirection URI instead of tokens for two purposes.
Browser-based flows expose protocol parameters to potential
attackers via URI query parameters (HTTP referrer), the browser
cache, or log file entries and could be replayed. In order to
reduce this threat, short-lived authorization codes are passed
instead of tokens and exchanged for tokens over a more secure
direct connection between client and authorization server.
It is much simpler to authenticate clients during the direct
request between client and authorization server than in the
context of the indirect authorization request. The latter would
require digital signatures.
Theoretically,
Access Tokens cannot tell us if the user has authenticated but auth code does.
Auth code should not be used to gain access to an API but access token should be.
If you have a single page application or mobile application with no or minimum backend, your application may want to access user's FB data directly at frontend. Hence the access token is provided.
In another case, you may want a user to register/login to your app using some external auth service provider like Facebook, Google etc. In this case, your frontend will send the auth code to the backend that can be used to get access token from Facebook at serverside. Now your server becomes enabled to access user's FB data from the server.
Basically, as an extension of Lix's answer, the access code route allows a Resource Owner (i.e. the Facebook User) to revoke authorization for their User Agent (i.e. their browser), e.g. by logging off, without revoking authorization for an offline Client (i.e. Your Application).
If this is not important, then there is no need to use the access code route.
Furthermore, the access code is provided to ensure that the Token provided to a server is actually registered to the Resource Owner (i.e. the Facebook User), and not the User Agent (or a Man-in-the-Middle).
This seems similar to the question of either choosing the implicit vs authorization code grant flow. In fact, here is what looks like an opposite view point?!.
Also, as Drew mentioned,
When the access token expires, attempts to use it will fail, and a new access token must be obtained via a refresh token.
another piece is the refresh token, but I don't see that being explained too well in the FB Docs. If I'm correct, the implicit grant (the direct token) should be really short lived, but that is to-be-enforced and FB.js seems to hide a lot of that (this one I have not looked as deep into).
If I'm correct, the code%20token is an optimization allowing both the User Agent to have a token and allowing for the server to initiate the token exchange process in a single request (as anything over Network IO is considered expensive, especially to a User Agent).
In OAuth 2.0 with facebook, the overall concept is simple as follows.
Step 1. Obtain "Authorization Code" by a GET request
request URI: https://www.facebook.com/dialog/oauth
Params:
response_type=code
client_id={add your "App id" got by registering app}
redirect_uri={add redirect uri defined at the registration of app}
scope={add the scope needed in your app}
Headers: None
Step 2. Obtain the "Access Token" by sending the authorization code as a POST request
URI: https://graph.facebook.com/oauth/access_token
Params:
grant_type=authorization_code
client_id=<add your "App id" got by registering app>
redirect_uri=<add redirect uri defined at the registration of app>
code=<obtained authorization code from previous step>
Headers:
Authorization:Basic encode <App Id:App Secret> with base64
Content-Type:application/json
Step 3. Use the access token got from above step and retrieve user resources
It’s because the access token is given to an AUTHENTICATED client (third-party app) using a shared secret that only FB and the client knows. The only way that the user could directly request the access token is by knowing the shared secret, which would make the secret public and could lead to a man-in-the-middle attack. Further, while FB can guarantee a secure connection to the user, FB can’t guarantee the handoff of the token to the client is secure. However, FB (and OAuth2) does require a secure connection between the client and FB. The access token is tied to the client public ID (usually hashed), which means only the original client application can use it to request the token because the secret is sent along with the authorization code to get the access token.
You recieve a token when the user logs in. But you might want to change the token when you are performing other actions. EG posting as your app/page or posting as a user with offline_access.