using captcha in mobile apps - android

I am looking for an alternative for captcha to use in our mobile applications. We are writing a mobile application in iOS and Android. The web application is already exist. In the web page we are using captcha to ensure only genuine customers are applying and to prevent denial of service type attacks.
So from mobile app also we need to take care of these. Any body came across the same situation? Is it recommended to use captcha in native mobile apps?

A mechanism to prevent automated traffic must definitely be used. Not doing so means you will allow a way to access your servers which can be automated. Even though you might think it is only available from mobile apps, an attacker code can run anywhere and bring your system to halt.
If your concern is that captchas will be inconvenient to mobile users, try google Recaptcha. Where usually its a click of checkbox or clicking some images in some cases where google is not able to determine based on the checkbox.
https://www.google.com/recaptcha/intro/index.html

There is a library for android using google recaptcha
https://github.com/ayltai/Android-Lib-reCAPTCHA
Android-Lib-reCAPTCHA
The reCAPTCHA Android Library provides a simple way to show a CAPTCHA as an ImageView in your Android app, helping you stop bots from abusing it. The library wraps the reCAPTCHA API.
Quick Start
First you have to sign up for your API keys.
Installation
repositories {
jcenter()
}
dependencies {
compile 'android.lib.recaptcha:reCAPTCHA:+'
}
The Layout
To show CAPTCHA image, you need to add a <android.lib.recaptcha.ReCaptcha /> element to your layout XML:
android.lib.recaptcha.ReCaptcha
android:id="#+id/recaptcha"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:scaleType="centerInside" />
It is important to use android:scaleType="centerInside" to ensure the entire CAPTCHA image can be displayed.
Alternatively, you can create an instance of android.lib.recaptcha.ReCaptcha at runtime:
ReCaptcha reCaptcha = new ReCaptcha(context);
How to show CAPTCHA
In your activity/fragment/view containing android.lib.recaptcha.ReCaptcha, you need display a CAPTCHA image for the user to response:
ReCaptcha reCaptcha = (ReCaptcha)findViewById(R.id.recaptcha);
reCaptcha.showChallengeAsync("your-public-key", onShowChallengeListener);
showChallengeAsync downloads and shows CAPTCHA image asynchronously. It is safe to invoke in UI thread. No exception will be thrown in case of any error by this call. All errors will be treated as unsuccessful in showing CAPTCHA image.
onShowChallengeListener is an instance of ReCaptcha.OnShowChallengeListener, which is called when an attempt to show a CAPTCHA is completed.
The synchronous version of this method is showChallenge.
How to verify user input
To verify user input, pass the input string to ReCaptcha.verifyAnswerAsync (or ReCaptcha.verifyAnswer):
reCaptcha.verifyAnswerAsync("your-private-key", "user-input", onVerifyAnswerListener);
verifyAnswerAsync asynchronously submits the user input string to reCAPTCHA server for verification. It is safe to invoke in UI thread. No exception will be thrown in case of any error by this call. All errors will be treated as verification failure.
onVerifyAnswerListener is an instance of ReCaptcha.OnVerifyAnswerListener, which is called when an attempt to verify the user input is completed.
The synchronous version of this method is verifyAnwser.
Specify a locale
You can force the widget to render in a specific language. Please refer to this page.
reCaptcha.setLanguageCode("fr");
Sample Application
A complete sample application is available at https://github.com/ayltai/Android-Lib-reCAPTCHA/tree/master/reCAPTCHA-Samples.

Related

How to get list of downloaded apps (paid/free) by a user from Google Play?

I recently came across this app Purchase Apps, which is somehow able to retrieve apps I've paid for in google play after I signed in using my google account.
I'm trying to find out how it is being done as I want to build a similar app, but for the free apps which were downloaded.
However, I can't find which OAuth API Scope was used for retrieving that information, even after going through the entire list of APIs.
EDIT:
I'm putting a new bounty on this question, as suggested by a similar question I've asked about here, and because here and there I don't see a real answer about how to do it, and what can be done with it.
I'd like to refine the questions into multiple pieces:
What is the API that can be used to get information of purchased apps? Where can I read about it? Please show a full, working example of how to do it.
Can it do more ? Maybe perform search? Maybe show free apps that were installed? Maybe the time they were installed and uninstalled? And the categories of those apps?
Are there any special requirements for using this API ?
EDIT: I'm putting a max bounty on this, because no matter how much I've read and tried, I still failed to make a POC that can query the apps from the Play Store that the user has ever downloaded (name, package name, date installed and/or removed, icon URL, price...), including both paid and free apps.
If anyone finds a working sample, show how it's done, and also show how you've found about it (documentation or anything that has led you to the solution). I can't find it anywhere, and the current solutions here are too vague for me to start from.
Issue is resolved. The exploit has been closed.
We will be closing this bug due to being logged in a Preview version of Android. If the issue is still relevant and reproducible in the latest public release (Android Q), please capture a bugreport and log the bug in https://source.android.com/setup/contribute/report-bugs. If a reply is not received within the next 14 days, this issue will be closed. Thank you for your understanding.
Latest update:
This is a bug and Google will address it in the next update.
We've deferred this issue for consideration in a future release. Thank
you for your time to make Android better
This answer has turned into a conglomeration of ideas and been edited to include information from discussion in the comments.
The androidmarket api, would be a customised api written by the developer. It's not available to the public.
To address your concerns in the comments. The developer would have utilised the current apis available through Android Developer and Google to create a project that manages all of these.
As for accessing Full Account Access, I'm not sure exactly how these developers have achieved this.
I'd recommend using the AccountManager, which is part of android.accounts, has access to credentials and a method getUserData. The account manager has access to passwords and is capable of creating and deleting accounts. This, possibly used with Content Provider
See Udinic/SyncAdapter Authentication.
To reply to your comment:
This blog should help you to get started. Write your own Android Authenticator.
How these apps actually work, I cannot tell you. They may also have different implementations (unless they're a collaborative effort behind the scenes, they most certainly will be different).
One guess. Firstly use GoogleSignInAccount with com.google.android.gms.auth.api.signin.
There a definition for scope, to determine the extent of the permissions the app is granted.
Using requestScopes(), the
public static final String PROFILE
.../ It lets your web app access over-the-air Android app installs.
For example:
GoogleSignInOptions gso =
new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
.requestEmail().
.requestScopes(new Scope("https://www.googleapis.com/auth/contacts.readonly"))
.build();
If full access can be gained a list of all apps used by the account holder can be found and compared to what's on the device.
Package Manager will retrieve a list of all apps currently installed on the device.
PackageInfo provides the details about the app.
INSTALL_REASON_USER will also filter out apps that have been actively installed by the user.
You might want to look at com.google.firebase.appindexing and Log User Actions. Different actions can be tracked.
The users account history is found at https://myactivity.google.com/myactivity.
A helpful link is the OAuth 2.0 Playground.
This github repo node-google-play, using node, is current and will call Google Play APIs. As did the archive that was used as an "unofficial" api, android-market-api, to query the market place.
App 1
The app claims to use the following permissions:
Version 2.1.8 can access:
$ In-app purchases
Other
receive data from Internet
view network connections
full network access
use accounts on the device
prevent device from sleeping
read Google service configuration
Noteworthy, the app doesn't set any permissions when there was a basic, install. I was unable to use any of the features, as I have no paid apps. So for the initial search - there were no permissions needed, which would indicate the app didn't have access to my account.
I checked the permissions - there were none set. So the only thing required was to accept the pop up, as displayed in your question.
App 2
The other app you refer to that does the same thing is more upfront about what is being accessed.
My Paid Apps
SECURITY/PRIVACY NOTICE
The first time you run this app, it will ask for full permission to your Google account. This is unfortunately
the only way to access the required information. No personal
information is stored, no information about your apps is shared with
the developer of this app, nor shared with any third parties.
Everything is kept on your phone only.
I've gone into detail over these apps in this blog post, which was for a university capstone project (no monetary gain). I'm inclined to think this is an exploit in the API and not status by design by Google, as there are no API calls to fetch purchases of apps other than the developer's own app. I hypothesize it's a zero day exploit, in which case there's no legitimate way to access this information.
In case of one of these applications (My Paid Apps), after checking the network traffic it is pretty obvious that it does use the Store's Account page to retrieve the list of paid applications.
Now, the mechanism it uses is the same mechanism that Google Chrome currently, and Pokemon GO supposedly at a point in time used.
In a nutshell, steps to do so are as follow:
Login:
What the mentioned program do for the first step is to log the user in and get access to the user's access token. To do so, it uses the android.accounts.AccountManager.getAuthToken() method. (See more: AccountManager)
However, as for the token scope, oauth2:https://www.google.com/accounts/OAuthLogin is requested.
It might be important to note that based on the OAth2 documentation from Google, this scope is not valid; however, it seems like a valid scope for Google OAuth v1.
Converting the newly retrieved access token to a ubertoken:
Now, what actually ubertoken supposed to do, is unknown and there is no official documentation about it. However, it was seen in the wild to be used by chrome browser to login users.
This is done by requesting the https://accounts.google.com/OAuthLogin?source=ChromiumBrowser&issueuberauth=1 page.
Converting ubertoken to website session:
Later on, using the newly created ubertoken it is possible to get a website session using the https://accounts.google.com/MergeSession API endpoint. After this step, the application is essentially capable of loading all personal pages that you can open using your browser while logged in; except some special pages including Payment settings.
Retrieving the list of paid applications:
Requesting and parsing the https://play.google.com/store/account page.
Following is the application's traffic as captured by 'Packet Capture':
As it is clearly visible in the picture, the end result is identical to what I get when I normally open the store's account page on my PC with Chrome Desktop:
Side note:
It seems none of these endpoints are documented as they are primarily used by Google's own programs and should be considered internal. Therefore I strongly recommend not using them in any program or code that you expect to run for a long time or in a production environment.
Also, there is bad news here for you too, it seems that the Google Play's account page only lists paid applications or special free apps (more especially OEM apps). I will try to find some time and dig deeper into the other application.
Interesting articles:
Pokemon tokens
Exploiting Google Chrome's OAuth2 Tokens
If you have root access, You can access /data/data/com.android.vending/databases/library.db
OnePlus3T:/data/data/com.android.vending/databases
-rw-rw---- 1 u0_a2 u0_a2 229376 2018-12-26 18:01 library.db
This database has all information, which app you have downloaded, which apps you have purchased, and even in which app you have done IAP.
Check ownership table, It has all information.
ownership (account STRING, library_id STRING, backend INTEGER, doc_id STRING, doc_type INTEGER, offer_type INTEGER, document_hash INTEGER, subs_valid_until_time INTEGER, app_certificate_hash STRING, app_refund_pre_delivery_endtime_ms INTEGER, app_refund_post_delivery_window_ms INTEGER, subs_auto_renewing INTEGER, subs_initiation_time INTEGER, subs_trial_until_time INTEGER, inapp_purchase_data STRING, inapp_signature STRING, preordered INTEGER, owned_via_license INTEGER, shared_by_me INTEGER, sharer_gaia_id TEXT, shareability INTEGER, purchase_time INTEGER, PRIMARY KEY (account, library_id, backend, doc_id, doc_type, offer_type))
Dealing with unofficial Google APIs is incredibly complicated territory. It's going to be possible to get this to work, but that's all I'll say. Proceed at your own risk.
The first thing you're going to need to do is get a Google Play auth token. This can be done several ways, but here's how they do it in Purchased Apps:
public static String getAuthToken(Activity activity, String userEmail) {
AccountManager accountManager = AccountManager.get(activity);
Account userAccount = new Account(userEmail, "com.google");
Bundle options = new Bundle();
options.putBoolean("suppressProgressScreen", true);
String token;
try {
Bundle result = accountManager
.getAuthToken(userAccount, "androidmarket", options, activity, null, null)
.getResult();
token = result.getString("authtoken");
} catch (OperationCanceledException e) {
Log.d(TAG, "Login canceled by user");
return null;
} catch (IOException | AuthenticatorException e) {
Log.e(TAG, "Login failed", e);
return null;
}
return token;
}
A few things to note here:
The above code must be run asynchronously. I recommend RxJava, but an AsyncTask will work.
You must supply a email for the account you want to use. I'll leave the details up to you but this is fairly easy using AccountManager.
After you have an auth token, you can now access any Google Play Store endpoint. The main one used by Purchased Apps is https://android.clients.google.com/fdfe/purchaseHistory. Another one you might be interested in is https://android.clients.google.com/fdfe/details?doc=(package name) (from APKfetch code). Here's a page with some more and some analysis. If you make a request to these APIs, you'll need to supply several headers:
Authorization - "GoogleLogin auth=(your auth token)"
User-Agent - "Android-Finsky/6.4.12.C-all%20%5B0%5D%202744941 (api=3,versionCode=80641200,sdk=" + VERSION.SDK_INT + ",isWideScreen=0)";
X-DFE-Device-Id - your device's Google Services Framework ID, obtained from AdvertisingIdClient.
X-DFE-Client-Id - "am-android-google"
Accept-Language - The device's language code, eg "en".
Now, you need to parse the response. Here's where things get tricky. These APIs returns a message encoded as a Protobuf, so it's essentially just binary data unless you have a schema (which of course, only Google has). One way to go about this in theory is to decompile the Google Play Store app and reuse their generated protobuf models with a tool like JADX.
Unfortunately, I've tried this and it doesn't really work. Protobuf model classes are just too complex for a standard decompiler. What you can use is a tool called PBTK. You'll ideally want to run this on the Google Play Store 6.1.12 APK, since that's the last version before they started using ProGuard. Do note that this program has two errors in its script that need to be fixed before running it: changing 'extracto' to 'extractor' in gui.py and removing the assertion statement on line 500 of jar_extract.py.
Now, that should output all of the response classes as .proto files. Create a folder under src/main called proto and drag the entire generated 'com' directory to it. You can delete everything that's not under com/google/android/finsky/protos. Follow instructions online to setup Gradle with the Protobuf Lite plugin.
When you want to parse a response, you can use the ResponseWrapper class, since they all appear to be contained under that.
That's about as far as I can take you. There's a good chance I got some part of this wrong; JADX is your best friend here, because the best way to figure out what an app is doing is by looking at its code. Hope this helps and happy developing!
you can get the package name of all installed apps on device and then get the information of every installed package that you find in the device from google play without any need to get to user account. there is some third party or unofficial apis to get google play apps details as json by getting the app package name. for example: https://42matters.com/
then use the received information for every package to find free ones.
i have two resources for you to consider, but first, in a word, no. there is no api from GOOGLE to let you do what you want, as these metrics arent stored in the phone, they are on the google play store servors, and google has no OFFICIAL api for the play store. you can however glean some info from these two sites:
https://www.quora.com/Is-there-an-API-for-the-Google-Play-Storeenter link description here
https://android.stackexchange.com/questions/162146/how-to-see-all-the-apps-i-have-downloaded-from-google-play-store
and this is enough to see how to accomplish this.
first, a list of what apps have been downloaded by an account is only referencable by the account. and this can be done through the play store. since your app will be installed on that users phone, this dosnt matter... you're in.
second, you will need a 3rd party API built for the GOOGLE PLAY STORE, there are some out there, check the first link.
using the api of your choice, you will send a get request, to the play store, and in return you should receive in most cases a json object to deserialize.
deserialize the object, and you will have your list. which list you get will depend on the endpoint you use, but that should be explained by/in the API itself.
good luck!

Chrome extension: Authenticate with backend without user interaction

In our Android app we are able to get authentication tokens without any user interaction (for the purpose of knowing that an api call was received from our app, not for the purpose of getting any user info)
We use:
GoogleAuthUtil.getToken(context, anyAccount, "audience:server:client_id:" + MY_CLIENT_ID);
How can we do something similar to authenticate api-calls from a chrome extension?
UPDATE:
This is how we get authentication w/o user interaction on Android:
http://android-developers.blogspot.co.il/2013/01/verifying-back-end-calls-from-android.html
Fortunately when calling getAuthToken, you can pass a flag ('interactive': true) or ('interactive': false)
('interactive': true)
If you invoke the API in interactive mode, the user is shown a sign in and/or approval UI when necessary, as shown in the screenshot below:
('interactive': false)
If you invoke the API in silent mode, the API will only return a token if it's possible to produce one without showing any UI. This is useful in cases when an app is doing the flow at app startup, for example, or in general in cases where there is no user gesture involved.
NOTE
The best practice we suggest is to use silent mode when there is no user gesture involved and use interactive mode if there is a user gesture (for example, the user clicked the Sign In button in your app). Note that we do not enforce any gesture requirement.

Authorize user on Google website in WebView via dialog

For example, user is navigating to google.com in WebView.
Is it possible to authorize him there via Google Account Picker (something like described here https://developers.google.com/android/guides/http-auth) to simplify authorization instead of manually logging in via web form?
Android Web browsers (for example, Google Chrome) are authorizing user via this method).
Part I: Using the Google Plus Services API
If I understand your question correctly, you may be able to achieve what you are trying to do using the Google Plus Services API.
You create your GoogleSignInOptions and then create your GoogleApiClient using these sign-in options. From there, you use the Auth.GoogleSignInApi.getSignInIntent with your GoogleApiClient as the parameter.
This intent should launch a SignInIntent that presents the Google account picker (that will include accounts that have been accessed on the device previously, and the ability to add another account).
Once you get back the GoogleSignInResult, you can verify that the user was authenticated and then create the authentication flow as you would otherwise.
Even included in the Android SDK is the Google SignInButton, which you can use right in your layout instead of having to create a custom button for the sign-in.
Part II: Using WebViewClient
Now, if you are trying to use a WebView to authenticate them, your best bet is to extend the WebViewClient class.
Things you will need: clientId, clientSecret, and clientScope (all of these details will be given for you when you create your application in the Google Developer Console)
First things first, your URL to authorize will probably be as follows: https://accounts.google.com/o/oauth2/auth?response_type=code&clientId={your client id}&state={SOMESTATEINFO}&access_type=offline (access type if you want offline access). This should be the initial URL of your WebView
Next, you will want to modify your extended WebViewClient class. What you will want to do is override the shouldOverrideUrlLoading(WebView webView, String url) method to listen for your redirectURL. Probably the easiest thing to do is to use url.startsWith(<your redirect URL>) to detect this. You can then parse the response. If your response contains error, then it means something went wrong. Otherwise, you should get back two fields in the URL: code and state. If you do not get error back, then return true for shouldOverrideUrlLoading.
Once you get your code, you can create a new GoogleAuthorizationCodeFlow, using your client, scopes, and secrets.
Once you have your flow, you will need a GoogleTokenResponse, which you will be able to get using the code obtained above for your authorization code, using GoogleTokenResponse response = flow.newTokenResponse(<code>).setRedirectUri(<redirectUri>).execute().
Once you have done this, and you have your response, you can get your Credential using flow.createAndStoreCredential(response, null).
And voila, using this Credential, you can authenticate your calls.
Caveats I have not been able to get the WebView to recognize accounts that have been signed into on other web browsers, so the account picker may only show the accounts that have been signed into on the app-specific WebView.
tl;dr It is possible to do this with a WebView and WebViewClient, but it's messy and a little bit more roundabout than using the Google Plus Services API.
This example better illustrates the authorization flow/credential stuff once you get the authorization code and such.
And here's some documentation on the WebViewClient that may be useful as well.
Hope this helps point you in the right direction!

App Indexing in android

I have implemented the app indexing in my application but its not working and showing below messages.
Deep link page : http://m.cardekho.com/carmodels/Hyundai/Hyundai_EON
Google could not get all the resources for this page:
https://graph.facebook.com/v2.0/244697749072142/activities?access_token=&format=json&sdk=android
https://graph.facebook.com/v2.0/244697749072142?format=json&sdk=android&fields=supports_attribution%2Csupports_implicit_sdk_logging%2Cgdpv4_nux_content%2Cgdpv4_nux_enabled
https://graph.facebook.com/v2.0/244697749072142?format=json&sdk=android&fields=supports_attribution%2Csupports_implicit_sdk_logging%2Cgdpv4_nux_content%2Cgdpv4_nux_enabled
https://track.appsflyer.com/api/v2.3/androidevent?buildnumber=1.15&app_id=com.girnarsoft.cardekho
The error message refers to resources which are either disallowed for crawling, or can't be accessed, but are deemed important for the page structure. In this case it's the former.
At https://graph.facebook.com/robots.txt it's currently showing:
User-agent: *
Disallow: /
To work around this, you would either convince Facebook to remove the disallow line so clients can access those resources, or you could modify the app so it relies less on the roboted (disallowed) resources.

Phonegap / Cordova ChildBrowser won't run Twitter web intents (SSL?)

I'm trying to integrate Twitter sharing functionality into my Android PhoneGap application, and rather than re-implement the controls to shorten URLs and track tweet length, I thought I'd use their premade web intents at https://twitter.com/intent/...
So I'm trying to launch a URL like https://twitter.com/intent/tweet?text=Hello in a ChildBrowser window, so that I can let Twitter's interface take over. The user could sign in with their credentials, and once they're signed in, the text from the URL params would appear in the Tweet box.
It won't work. When I use http://twitter.com/intent/... instead of https://twitter.com/intent/... , ChildBrowser displays the sign-in screen, but as soon as the user submits their credentials, the screen goes white. I suspect this is because Twitter switches over to HTTPS.
I confirmed that this was the case by trying a simple window.open instead of window.plugins.childBrowser.showWebPage. I have no problems with HTTP / HTTPS when using the native browser on Android. However, the native browser prompts me to accept an unverified security certificate. I suspect this is the problem with ChildBrowser - it doesn't know how to handle that prompt.
Using the native browser popover simply isn't an option: the user needs to be able to exit the process after hitting 'Tweet' or 'Follow', etc., but the 'back' button on the Android device simply moves the history one step backward to the POST action for their intent. Then, it re-launches the app from scratch, instead of returning you to the original state.
How can I configure ChildBrowser / my Android Phonegap application to override SSL issues on Twitter, so that I can run web intents in Childbrowser?
The relevant code is:
base="https://twitter.com/intent/tweet?text=";
URL=base+encodeURIComponent("it works!");
// works, but asks to accept a certificate
window.open(URL);
// blank white page
window.plugins.childBrowser.showWebPage(URL, { showLocationBar: true });
My cordova.xml file has whitelists configured as such:
<access origin="http://127.0.0.1*"/> <!-- allow local pages -->
...which I don't suspect should be a problem. However, a basic test of swapping origin=".*" yielded no change in behaviour.
I've also examined the HTTP and HTTPS headers for the Twitter intent landing pages. There doesn't appear to be anything out of line - they're identical, except for the Strict-Transport-Security header for HTTPS, which works elsewhere (e.g. Github).
Please help!
The ChildBrowser is not bound by the whitelist. The whitelist is only used to keep the main PhoneGap app from running code outside of trusted domains.
I'm confident if you go get the latest ChildBrowser code from Android you won't have run into this problem anymore. We've made some changes recently that make it more robust.
Also, Libby has a good tutorial integrating Twitter and the ChildBrowser.
http://www.mobiledevelopersolutions.com/home/start/twominutetutorials/tmt5p1

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