I am developing a Xamarin forms application. The app is for company owners in which they can see the employee timesheets.The app can be accessed by userid and password which will authenticate via API.Iam intend to save the user credentials in app and provide a logout facility when they want.
My questions are
1. How can I securely store user credentials in xamarin forms , in which nobody should get the credentials by decompiling the app.
2. How can I securely pass the credentials via API and authenticate (I heard about base auth, OAuth) it with server.
3.If someone gets my user credentials and URL to post, but he should not get the
data.How can it be implemented?
Show me some guidance and links. Thanks in advance !
This question has nothing to do with Xamarin.Forms, it is more about general architecture and security considerations.
You should not store user credentials but an authentication token that will be returned from the API in case of a successful user authentication. This token should have a limited lifetime - depends on the business needs.
HTTPS
Since you will not store sensitive data like user login and password on the phone, the risks of someone obtaining those will be slightly minimised. In any case you could invalidate the token if a malicious behavior will be detected and force the user to change the password.
For storing the authentication token securely on the device you could use Xamarin.Essentials
Related
I am building an ASP.NET Core 6 Web API application for mobile clients (and maybe later SPA JS app). The application should have sign-in with Google option. I also want to add my own app's custom sign up and sign in options that would also be based on JWT authentication and not cookie.
I understand that for my custom sign in flow my app will generated JWT that will be sent to the client.
But I have few questions how that works when user signs-in with its Google account:
who's responsibility is to generate the JWT when user signs-in with its Google account? Is that responsibility of Google or mine application? I don't want Google to return JWT to the client in the cookie.
Then when client is authenticated with Google, and sends requests to my application, how can my application validate JWT token it gets?
When user signs in with Google for the first time, should I automatically register that user in my application (I am using Identity framework) by taking claim values (email) from the JWT? What is the general practice here?
I am trying to understand these processes and flows so sample code is not necessary (but I do welcome it).
Ad.1. Normally, in a larger system, you would have an authorization server (AS) that would handle user authentication and the issuance of tokens. Your clients would contact only the AS, and the AS will be able to provide the user with different forms of authentication: e.g., through your website's password or through Google. The AS is the single point of issuing tokens to your clients. It can issue tokens regardless of the authentication method used. So it then doesn't matter whether the user authenticated with Google or a password, the client will still get the same access token.
Ad.2. When the AS issues token to your client, then you don't have any problems validating that token. The client doesn't care if the user authenticated with Google or not, it's not relevant in this case.
If you decide to skip using an AS and let the client receive tokens directly from Google, then you can still verify them. An ID token is a JWT and can be easily validated with a JWT library using verification keys provided by Google. Access tokens returned by Google are opaque tokens (If I remember correctly), and you need to check whether Google exposes an endpoint to verify them.
Ad.3. That is the general practice. When the user authenticates with Google and you notice that you don't have that user's data in your system, then you take the information from Google's ID token and create a user entry in your system.
I am wondering if there is anyway to check if the entered username and password is correct despite of enforcing multi factor authentication in Azure Active Directory?
I have set up an app with application permission(with admin consent) as well as delegated permission and is able to test both approach using ConfidentialClient and PublicClient using MSAL library.
I am not able to run my web form app in IIS with the PublicClient approach which is interactive and displays you a popup for the Microsoft login. So, the only approach I see here is to use app-only authentication.(https://learn.microsoft.com/en-us/exchange/client-developer/exchange-web-services/how-to-authenticate-an-ews-application-by-using-oauth )
I can use the confidential client(app only) since I have all the required admin consents granted to get the OAuth token and then impersonate the user to access to EWS managed api.
But the requirement is the user should enter their outlook password in the webform app before loading their emails(from EWS Managed API which needs OAuth token).
At this point I am not sure what to do next. Please help. Also let me know if you need more information.
For more reference why I am no able to use delegated authentication: Why app is throwing error in test environment but working fine in local machine using ASP.NET Web Forms and MSAL?
Per my understanding, you want to check the username and password by Azure AD first and using the confidential client to call APIs on behalf of the user.
This way is something hacking, but I think it works for this scenario. Just try the request below:
POST https://login.microsoftonline.com/<tenant id>/oauth2/v2.0/token
Request Body:
client_id=<confidential client app id>
&Client_secret=<confidential client app sec>
&grant_type=password
&scope=https://graph.microsoft.com/user.read
&username=<username>
&password=<password>
If the user typed the wrong user name and password, the response would be:
If username and password are all right, the response report the MFA related info:
I have a question more related to the way OAuth 2 is working but since using IdentityServer to implement OAuth I think it's relevant. I could not find an answer anywhere.
I'm building a website and a mobile app that consumes my own API. Each user of my app will have a username and password, that will give him access to the app/website and though the API to his information.
I'm not sure about the right way to handle the flow for user login:
On the website I have my own designed login form. I don't want to move the user to my auth server to login, and then have him approve the information he gives - he is the user on my system - I have access to all information - kida like facebook has a login and access to the informatio - they don't ask what you're willing to give them. So is implicit really the way for this?
On the mobile app I also have a login form and now I read here (https://datatracker.ietf.org/doc/html/draft-ietf-oauth-native-apps-10) that the OAuth approach is to have the login in a WebView?? Doesn't look like facebook login is in a WebView on their mobile app.
The approach I was first lookin at is the Resource Owner. Users will login, get the token and the refresh token and can start working against my APIs. But storing my client_id and secret on the mobile app? on the website javascript files? doesn't feel right. I can of course make a call to an API that will mask those and be a proxy to the login process... but... (read #4).
In the future I would like to allow access for third-party developers. For them to allow login for users of my system I will use the implicit flow. Also, I plan for those developer accounts to have restricted API access (for example, the number of calls to the API will be limited by plan). What prevents those developers from asking for the username and password of their account on my system on their website, getting the response from my servers with the access token and refresh token, and using my API however they want, without restrictions, and having access to the entire user profile?
Lets say I'm sticking to the resource owner flow, receiving back from the server a token and a refresh token. What should I store on the mobile device and how? What should be stored in the browser and how? the refresh token? and each time he opens the app get a new updated token with that refresh token?
Edit
Just to clarify, because I find a lot of lectures and articles that explain the process from an API consumer point of view (ie. the third-party developer): I am the API owner and the auth server owner, I'm the owner of the user accounts (they are my users of my services), I'm also my own consumer (though the website and the mobile app), and in the future I want to enable third-party developers to allow my users to login with their accounts of my service (kinda like Facebook or Google)
You're correct that you shouldn't store the client_secret in your app, but I doubt you will get around storing the client_id. You could disable the consent screen for your app as well, and build a native login view. You need to store the access_token and the refresh_token on the device (maybe encrypted in a database) if you don't want the user to login everytime they use your app.
As for problem 4, you could do the following:
Embed the client_secret in your (web) app
Set up which hosts have access to your api on the IdentityServer
The IdentityServer generates a salt and sends it to the client
The client calculates a session_secret using hash(ip_address + session_salt)
The client uses the session_secret and the client_secret for the API call
Server validates the hash and client_secret
It's nearly impossible to completely prevent someone from using your API. But you should add various rate limiting methods, such as limiting IP addresses, API calls etc. But nothing will stop someone decompiling your app and accessing your client_id.
I'm working on a personal project composed of an API and 4 clients (web, android, iOS, windows phone).
I'm using django-rest-framework and oauth2 toolkit on the API side and I wonder which grant_type would be more suitable in my situation.
I read somewhere that the implicit grant_type is appropriate for working with mobile clients.
I'm currently using the resource owner password credentials system.
My current workflow is:
The user creates an account on the API registration page (http://mysite/api/register) then gets redirected on the web client.
The user have to authenticate himself on the API from the web client (the secret and client ID are store in the web client). If the authentication is successful the access_token and refresh_token are both stored in the user session.
Each time the user want to access a page I verify if he is authenticated by requesting the API using his access_token. If the request fails, I retry with the refresh_token. If it's fails again I redirect the user on the auth page.
The user can use the API on a mobile client with the same account without extra manipulations (the secret and client ID are store in a secure location ex. share preferences or keychain)
I like this workflow, it's simple and convenient for the user: he registers once and can use all the clients and I get a perfect separation between the logic (API) and the UI (client). But I'm worried about the security of this system. I don't want to expose my users to threats. Do you guys have any thoughts, recommendations, suggestions?
You help in this matters would be very appreciated.
Thanks in advance!
I'm working on a mobile application, in which, the user can go for Facebook, Twitter or Foursquare authorization (via OAuth) rather than creating a new account and password.
The problem is, I'm not sure what should I store in my DB to point a 3rd party account. The auth_token, acquired from OAuth process seems to expire or change in some situations (like when the user changes password). So, it's not a good option.
What would be the long term option? I mean, even if user unauthorized my app, then authorizes it back, I would like to be able to find out the local user corresponding to them. Should I use the respective API's of each website and dig out user_id and store it? That would be consistent in between sessions I believe.
Any suggestions?
Thanks.
When you are getting the authorization from the sites, you need to only store the access_token (and refresh token if OAuth 2.0). With a OAuth 2.0 access_token, it will expire occasionally and you will need to use the refresh_token to get a new access_token. The user changing the password will not change the token, but the user would have the ability to revoke the token at any time.
Since they have to go through your mobile app to get the OAuth authentication, you should be able to link them together easily.