Develop Reference

Decode private relay email

I'm developing Apple Authentication feature on Android with React Native, using this library: https://github.com/invertase/react-native-apple-authentication. Everything goes fine, but there is still a thing I want to show in the form is that the real email, or Apple ID of the user. The default settings of Apple accounts is that use private relay, so after I call signIn() method in this code fragment
// App.js
import { appleAuthAndroid } from '#invertase/react-native-apple-authentication';
import 'react-native-get-random-values';
import { v4 as uuid } from 'uuid'
async function onAppleButtonPress() {
// Generate secure, random values for state and nonce
const rawNonce = uuid();
const state = uuid();
// Configure the request
appleAuthAndroid.configure({
// The Service ID you registered with Apple
clientId: 'com.example.client-android',
// Return URL added to your Apple dev console. We intercept this redirect, but it must still match
// the URL you provided to Apple. It can be an empty route on your backend as it's never called.
redirectUri: 'https://example.com/auth/callback',
// The type of response requested - code, id_token, or both.
responseType: appleAuthAndroid.ResponseType.ALL,
// The amount of user information requested from Apple.
scope: appleAuthAndroid.Scope.ALL,
// Random nonce value that will be SHA256 hashed before sending to Apple.
nonce: rawNonce,
// Unique state value used to prevent CSRF attacks. A UUID will be generated if nothing is provided.
state,
});
// Open the browser window for user sign in
const response = await appleAuthAndroid.signIn();
// Send the authorization code to your backend for verification
}
I got an id_token, after I decode the token, I got an object in this pattern:
{
"aud":"",
"auth_time":,
"c_hash":"xxxxxxx",
"email":"xxxxxxx#privaterelay.appleid.com",
"email_verified":"true",
"exp":1663743691,
"iat":1663657291,
"is_private_email":"true",
"iss":"https://appleid.apple.com",
"nonce":"xxxxxxxxxxxxxxxxxx",
"nonce_supported":true,
"sub":"xxxxxxxxxxxxxxxx"
}
whose the email is not the real email that the user entered before. So this can cause a confusion after that when I show the user's information in a form to confirmation, I can only use this private relay email. I wonder that whether any way to decode this email to get the real one, by using c_hash for instance.

Authenticating your client to Cloud Endpoints without a Google Account login

I have been doing extensive research on how to authenticate your client (Android, iOS, web-app) with Cloud Endpoints without requiring your user to use their Google account login the way the documentation shows you.
The reason for this is that I want to secure my API or "lock it down" to only my specified clients. Sometimes I will have an app that does not have a user login. I would hate to pester my user to now sign in just so my API is secure. Or other times, I just want to manage my own users like on a website and not use Google+, Facebook, or whatever else login authentication.
To start, let me first show the way you can authenticate your Android app with your Cloud Endpoints API using the Google Accounts login as specified in the documentation. After that I will show you my findings and a potential area for a solution which I need help with.
(1) Specify the client IDs (clientIds) of apps authorized to make requests to your API backend and (2) add a User parameter to all exposed methods to be protected by authorization.
public class Constants {
public static final String WEB_CLIENT_ID = "1-web-apps.apps.googleusercontent.com";
public static final String ANDROID_CLIENT_ID = "2-android-apps.googleusercontent.com";
public static final String IOS_CLIENT_ID = "3-ios-apps.googleusercontent.com";
public static final String ANDROID_AUDIENCE = WEB_CLIENT_ID;
public static final String EMAIL_SCOPE = "https://www.googleapis.com/auth/userinfo.email";
}
import com.google.api.server.spi.auth.common.User; //import for the User object
#Api(name = "myApi", version = "v1",
namespace = #ApiNamespace(ownerDomain = "${endpointOwnerDomain}",
ownerName = "${endpointOwnerDomain}",
packagePath="${endpointPackagePath}"),
scopes = {Constants.EMAIL_SCOPE},
clientIds = {Constants.WEB_CLIENT_ID, Constants.ANDROID_CLIENT_ID,
Constants.IOS_CLIENT_ID,
Constants.API_EXPLORER_CLIENT_ID},
audiences = {Constants.ANDROID_AUDIENCE})
public class MyEndpoint {
/** A simple endpoint method that takes a name and says Hi back */
#ApiMethod(name = "sayHi")
public MyBean sayHi(#Named("name") String name, User user) throws UnauthorizedException {
if (user == null) throw new UnauthorizedException("User is Not Valid");
MyBean response = new MyBean();
response.setData("Hi, " + name);
return response;
}
}
(3) In Android call the API method in an Asynctask making sure to pass in the credential variable in the Builder:
class EndpointsAsyncTask extends AsyncTask<Pair<Context, String>, Void, String> {
private static MyApi myApiService = null;
private Context context;
#Override
protected String doInBackground(Pair<Context, String>... params) {
credential = GoogleAccountCredential.usingAudience(this,
"server:client_id:1-web-app.apps.googleusercontent.com");
credential.setSelectedAccountName(settings.getString(PREF_ACCOUNT_NAME, null));
if(myApiService == null) { // Only do this once
MyApi.Builder builder = new MyApi.Builder(AndroidHttp.newCompatibleTransport(),
new AndroidJsonFactory(), credential)
// options for running against local devappserver
// - 10.0.2.2 is localhost's IP address in Android emulator
// - turn off compression when running against local devappserver
.setRootUrl("http://<your-app-engine-project-id-here>/_ah/api/")
.setGoogleClientRequestInitializer(new GoogleClientRequestInitializer() {
#Override
public void initialize(AbstractGoogleClientRequest<?> abstractGoogleClientRequest) throws IOException {
abstractGoogleClientRequest.setDisableGZipContent(true);
}
});
// end options for devappserver
myApiService = builder.build();
}
context = params[0].first;
String name = params[0].second;
try {
return myApiService.sayHi(name).execute().getData();
} catch (IOException e) {
return e.getMessage();
}
}
#Override
protected void onPostExecute(String result) {
Toast.makeText(context, result, Toast.LENGTH_LONG).show();
}
}
What is happening is that in your Android app you are showing the Google account picker first, storing that Google account email in you shared preferences, and then later setting it as part of the GoogleAccountCredential object (more info on how to do that here).
The Google App Engine server receives your request and checks it. If the Android Client is one of the ones you specified in the #Api notation, then the server will inject the com.google.api.server.spi.auth.common.User object into your API method. It is now your responsibility to check if that User object is null or not inside your API method. If the User object is null, you should throw an exception in your method to prevent it from running. If you do not do this check, your API method will execute (a no-no if you are trying to restrict access to it).
You can get your ANDROID_CLIENT_ID by going to your Google Developers Console. There, you provide the package name of your Android App and the SHA1 which generates for you an android client id for you to use in your #Api annotation (or put it in a class Constants like specified above for usability).
I have done some extensive testing with all of the above and here is what I found:
If you specify a bogus or invalid Android clientId in your #Api annotation, the User object will be null in your API method. If you are doing a check for if (user == null) throw new UnauthorizedException("User is Not Valid"); then your API method will not run.
This is surprising because it appears there is some behind the scenes validation going on in Cloud Endpoints that check whether the Android ClientId is valid or not. If it is invalid, it won't return the User object - even if the end user logged in to their Google account and the GoogleAccountCredential was valid.
My question is, does anyone know how I can check for that type of ClientId validation on my own in my Cloud Endpoints methods? Could that information be passed around in an HttpHeader for example?
Another injected type in Cloud Endpoints is the javax.servlet.http.HttpServletRequest. You can get the request like this in your API method:
#ApiMethod(name = "sayHi")
public MyBean sayHi(#Named("name") String name, HttpServletRequest req) throws UnauthorizedException {
String Auth = req.getHeader("Authorization");//always null based on my tests
MyBean response = new MyBean();
response.setData("Hi, " + name);
return response;
}
}
But I am not sure if the necessary information is there or how to get it.
Certainly somewhere there must be some data that tells us if the Client is an authorized and specified one in the #Api clientIds.
This way, you could lock-down your API to your Android app (and potentially other clients) without ever having to pester your end users to log in (or just create your own simple username + password login).
For all of this to work though, you would have to pass in null in the third argument of your Builder like this:
MyApi.Builder builder = new MyApi.Builder(AndroidHttp.newCompatibleTransport(),
new AndroidJsonFactory(), null)
Then in your API method extract whether or not the call came from an authenticated client, and either throw an exception or run whatever code you wanted to.
I know this is possible because when using a GoogleAccountCredential in the Builder, somehow Cloud Endpoints knows whether or not the call came from an authenticated client and then either injects its User object into the API method or not based on that.
Could that information be in the header or body somehow? If so, how can I get it out to later check if it is there or not in my API method?
Note: I read the other posts on this topic. They offer ways to pass in your own authentication token - which is fine - but your .apk will still not be secure if someone decompiles it. I think if my hypothesis works, you will be able to lock-down your Cloud Endpoints API to a client without any logins.
Custom Authentication for Google Cloud Endpoints (instead of OAuth2)
Authenticate my "app" to Google Cloud Endpoints not a "user"
Google Cloud Endpoints without Google Accounts
EDIT:
We used Gold Support for the Google Cloud Platform and have been talking back and forth with their support team for weeks. This is their final answer for us:
"Unfortunately, I haven't had any luck on this. I've asked around my
team, and checked all of the documentation. It looks like using OAuth2
is your only option. The reason is because the endpoint servers handle
the authentication before it reaches your app. This means you wouldn't
be able to develop your own authentication flow, and would get results
much like what you were seeing with the tokens.
I would be happy to submit a feature request for you. If you could
provide a little more information about why the OAuth2 flow doesn't
work for your customers, I can put the rest of the information
together and submit it to the product manager."
(frowny face) - however, maybe it is still possible?

I have implemented Endpoint Auth using a custom header "Authorization" and it works just fine. In my case this token is set after login but should work all the same with your app. Check your tests because the value should be there.
The way to retrieve that header is indeed:
String Auth = req.getHeader("Authorization");
You could take it a step further and define your own implementations of an Authenticator and apply it to your secure API calls.

So you don't have any user specific info, but just want to ensure that only your app is able to communicate with your backend...
This is what i think,
change
#Api(name = "myApi", version = "v1",
namespace = #ApiNamespace(ownerDomain = "${endpointOwnerDomain}",
ownerName = "${endpointOwnerDomain}",
packagePath="${endpointPackagePath}"),
scopes = {Constants.EMAIL_SCOPE},
clientIds = {Constants.WEB_CLIENT_ID, Constants.ANDROID_CLIENT_ID,
Constants.IOS_CLIENT_ID,
Constants.API_EXPLORER_CLIENT_ID},
audiences = {Constants.ANDROID_AUDIENCE})
{
...
}
to
#Api(name = "myApi", version = "v1",
namespace = #ApiNamespace(ownerDomain = "${endpointOwnerDomain}",
ownerName = "${endpointOwnerDomain}",
packagePath="${endpointPackagePath}"),
scopes = {Constants.EMAIL_SCOPE},
clientIds = {Constants.ANDROID_CLIENT_ID},
audiences = {Constants.ANDROID_AUDIENCE})
{
...
}
The Client ID is generated from the signature of your app. It can't be replicated. If you only allow your endpoints to accept requests from the Android App, your problem would be solved.
Tell me if this works.

Faced the same problem to find a solution to call my API safely from my endpoints, without using Google Account. We can't decompile an IOS App (Bundle), but decompile an Android App is so simple..
The solution I found is not perfect but do the job pretty good:
On android APP, I just create an constant String variable, named APIKey, with simply content (For example "helloworld145698")
Then I encrypt it with sha1, next md5, and finally sha1 (Order and frequency of encryption up to you) and store the variable on SharedPref (For Android) in private mode (Do this action on an random class in your App) It's this result encrypted I authorize on my Backend !
On my backend, I just add a parameter (named token for exemple) on every request
Example:
#ApiMethod(name = "sayHi")
public void sayHi(#Named("name") String name, #Named("Token") String token) {
if (token == tokenStoreOnAPIServer) {
//Allow it
} else {
//Refuse it and print error
}
}
On android, active ProGuard for obfuscated your code. It will be really unreadable for anyone who tried to decompile your app (Reverse engineering is really hardcore)
Not THE perfect secure solution, but it works, and it will be really really (really) difficult to find the real API key for anyone who try to read your code after decompilation.

WebApi: How to call Facebook Graph API by using an access token originated from the OAuth dialog

I have an ASP.NET WebApi 2.1 application with OAuth2 configured. I have and Android client where I can do authentication by using the following methods:
WebView approach (Web Api External Providers): redirect to https://www.facebook.com/dialog/oauth..., user do login there, FB asks for permissions, redirects to my url, catch it, access token got, done.
Facebook SDK approach: under the hood it does: redirect to https://graph.facebook.com/oauth..., user do login there, FB asks for permissions, redirects to my url, catch it, access token got, done.
The problem is, if I go with the WebView version, the token is good for authorizing user in my Web Api application, but I cannot call Graph API by using it, I receive OAuthException 190 (no subcode).
But if I do the SDK authorization, Graph API is accessible (through the Android Facebook SDK), but using the token I've got from it, Web Api authorization is not working, I get 401 by calling Authorization/UserInfo.
So my question are the above token types interchangeable somehow?
Any help would be greatly appreciated.

Sorry if that was not clear, I'm using Web Api w/ ASP.NET Identity 2.0 template, so OAuth plumbing code is already present there.
I was able to find an answer to my own question, let me share it with you.
So the problem is that the token I've got from the Facebook's OAuth dialog after the redirect is not the same token that my application can use to call Facebook Graph APIs in the name of the actual user. That Graph API token is reachable at the following point:
Assume you are using the mentioned template above, you can find App_Data/Startup.Auth.cs class with definition of a FacebookAuthenticationOptions instance. There you can catch the API token and can persist that into the database. For example:
var fbopts = new FacebookAuthenticationOptions
{
AppId = Global.Config.ExternalServices.FacebookAppID,
AppSecret = Global.Config.ExternalServices.FacebookAppSecret,
Scope = { "email", "user_friends", "publish_actions" },
Provider = new FacebookAuthenticationProvider
{
OnAuthenticated = async context =>
{
// This token will be OK for calling Graph API
string accessToken = context.AccessToken;
using (var tracer = Global.Tracer.CreateBuilder())
{
try
{
tracer.InformationLine("Storing Facebook OAuth token: " + accessToken);
string fbUserID = context.Identity.GetUserId();
string fbUserName = context.Identity.Name;
tracer.InformationLine("Facebook User ID: " + fbUserID);
tracer.InformationLine("Facebook User Name: " + fbUserName);
// Store it into the db
// assume Task StoreOAuthToken(string providerName, string providerKey, string accessToken) is defined
await StoreOAuthToken("Facebook", fbUserID, accessToken);
}
catch (Exception ex)
{
tracer.ErrorLine("Failed.", ex);
}
}
}
}
};
app.UseFacebookAuthentication(fbopts);
At this point you're gonna have a row in a table that consists of the following columns:
OAuthAccessToken.ProviderName
OAuthAccessToken.ProviderKey
OAuthAccessToken.AccessToken
Now you can provide an API to your consumers to have that API token for calling Graph API, like:
[Route("AccessTokens")]
[Authorize]
public async Task<List<OAuthAccessToken>> GetAccessTokens(string providerName = null)
{
var userID = User.Identity.GetUserId();
var q = from l in this.Context.AspNetUserLogins // Managed by ASP.NET Identity 2.0
from t in this.Context.OAuthAccessTokens // Stored by you with above code
where l.UserId == userID && t.ProviderName == l.LoginProvider && t.ProviderKey == l.ProviderKey
select t;
if (!string.IsNullOrEmpty(providerName)) q = q.Where(t => t.ProviderName == providerName);
return await q.ToListAsync();
}
So on Android after doing a Facebook login I have the Bearer token for my application's Web Api calls, and I can get my token for accessing Graph API by calling the action above.
Maybe there are easier methods for achieving the above. Please let me know if you find any.

Authenticate android app to call web api service

I have an android app that have a login form for student, and I want to check the student credential at web api depending on the stored data in sql server
I have searched the web and watch many videos that talking about many scenarios and nothing helped me.
All I want is a custom validation for my rest service (so I should send the credential for each request)
What should I do at asp.net web api service
how I can implement that at android application

Seems you didn't search for "Web API Token Based Authentication" ;) Anyhow what you need to implement is very simple.
You need to use OAuth 2.0 Resource Owner Credentials Flow which means that you want to provide the username/password only once for a specific endpoint i.e(/token) and then you if the username/password valid you obtain something called Bearer Access Token.
This token is valid for specified period and you can configure this in your Web API.
Once you obtain the access token, you need to store it securely in your android app, then you keep sending it with each request to your web api protected end points using the Authorization header (Bearer scheme(.
I've written very detailed post which covers your scenario 100%. Please check the post Token Based Authentication and let me know if you need further help.

I have used basic authentication for security,so I should provide the base64 encoding of
username:password
in header for each request as the following
authorization: Basic 'encoded username:password
httpGet.setHeader("Authorization", "Basic "+encodeUsernameAndPassword());
At the server side I have implemented message handler
public class BasicAuthenticationHandler : DelegatingHandler
{
public readonly IAuthenticationService authService;
public BasicAuthenticationHandler(IAuthenticationService service)
{
this.authService = service;
}
protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
AuthenticationHeaderValue authHeader = request.Headers.Authorization;
if (authHeader == null || authHeader.Scheme != "Basic")
{
return Unauthorized(request);
}
string encodedCredentials = authHeader.Parameter;
var credentialsBytes = Convert.FromBase64String(encodedCredentials);
var credentials = Encoding.ASCII.GetString(credentialsBytes).Split(':');
if (!authService.Authenticate(credentials[0], credentials[1]))
{
return Unauthorized(request);
}
string[] roles = null;//todo
IIdentity identity = new GenericIdentity(credentials[0], "Basic");
IPrincipal user = new GenericPrincipal(identity, roles);
HttpContext.Current.User = user;
return base.SendAsync(request, cancellationToken);
}

Google Cloud Endpoints and user's authentication

I'm currently new into the AppEngine world, and wanting to create a backend using Cloud Endpoints for a mobile application that I'm developing.
One of my problem right now is about the user's authentication. I've been following the Udacity's MOOC on App Engine, and they taught us how to authenticate the user for API request using a Google Accounts. On the backend side, we simply have to add a User parameter to our method, and check if the user is signed in. As far as I know, this user parameter is generated by App Engine, based on the Authorization header of our request. (might need some confirmation there)
Now, there's a bunch of stuff I'm not sure to understand and that weren't that well explained on this MOOC.
Now, I'd like to know if this is compatible with other OAuth schemes, beside Google? So, if I want to implement Facebook authentication, will I simply pass the facebook access token?
From what I searched, using the Facebook SDK on Android would lead me to be able to generate a User Access Token, which identifies my user to facebook. After sending it to my backend, I would want to check it's validity with Facebook, and if it's valid, create a new user to my application. Now, I'd also want to generate a new token that identify the user to my app. What would I need to do to do so?

You can supply your own authenticator to Endpoints and the injected User will be obtained with your authenticator
https://developers.google.com/appengine/docs/java/endpoints/javadoc/com/google/api/server/spi/config/Authenticator.html.
The Facebook credentials can be sent via a header, e.g. Authorization header and it can be accessed from backend via HttpServletRequest, which you can handle inside Authenticator.authenticate method.
For example.
// Custom Authenticator class
public class MyAuthenticator implements Authenticator {
#Override
public User authenticate(HttpServletRequest request) {
String token = request.getHeader("Authorization");
if (token != null) {
String user = authenticateFacebook(token); // apply your Facebook auth.
if (user != null) {
return new User(user);
}
}
return null;
}
}
// Endpoints class.
#Api(name = "example", authenticators = {MyAuthenticator.class})
public class MyEndpoints {
public Container getThing(User user) {
Container c = new Container();
if (user != null) {
c.email = user.getEmail();
}
return c;
}
public class Container {
public String email;
public String extraData;
}
}

When I try your example I always get an: java.lang.NullPointerException: authDomain must be specified. But I cannot set an authDomain on the User object. Any ideas?
UPDATE: This is connected to this Bug https://code.google.com/p/googleappengine/issues/detail?id=12060&q=endpoints&colspec=ID%20Type%20Component%20Status%20Stars%20Summary%20Language%20Priority%20Owner%20Log
in version 1.9.22