Android Generate Aes Gcm Key
Hi, this is my first post as a blogger, in this post I ‘ll show you how to send push notifications using GCM (Google Cloud messaging) from our HTTP server (or using curl, Postman or any Http Client).
Feb 12, 2017 Id like to take a moment and discuss how we can take advantage of the Android Keystore and store passwords, or any other sensitive data in it, encrypt the data, and decrypt that data right back. Jan 06, 2018 AES, also known by its original name Rijndael, was selected by the NIST in 2000 to find a successor for the dated Data Encryption Standard(DES). AES is a block cipher, that means encryption happens on fixed-length groups of bits. In our case the algorithm defines 128 bit blocks. AES supports key lengths of 128, 192 and 256 bit. Currently I am working in generating a key for AES encryption/decryption. The key is based on a password an a random salt per user. My first idea was to made a SecretKeyFactory with the algorithm 'PBKDF2WithHmacSHA1'. The problem is that Android currently does not support it.
This post shows the new method which is using google-services.json
Google provides GCM(Google Cloud Messaging) servers that allow sending downstream messages to registered Android devices and upstream messages from Device to Servers. In this post the focus will be only on the former part of sending downstream messages to Device from our server.
GCM Messages can have a maximum payload data of 4kb, enough to accommodate a Notification Title, the content and an image url and some other internal data that may be needed by the application for performing the required action like synchronizing the data like emails, product list, messages etc.
No, as Wenger has argued. 
Let us have a look at the working Architecture:-
Let me clear a major misconception that GCM Messages are Notifications, but GCM Messages are the payload (usually JSON data) that is sent from the server to our Device (or multiple devices), the android device receives the JSON payload in real-time and the code implemented in Android Application may or may not display a notification based on the data received.
So let us get started implementing the Push Notifications in our app. In first step we will generate a Server API Key, for identifying our server backend , In second step we will generate a device token that will be used as an identity for our device for receiving messages.
We need to register our application and generate the google-services.json which will contain the API keys required.
Open https://developers.google.com/mobile/add to GCM services to our app. Follow these steps to generate the google-services.json file
Click on “Pick a Platform”
Choose “Enable Services for my Android App” (in this case we are doing it for Android)
Give your application name in “App name” and the package name for our application in “Android package name”, in case you don’t know the package name, you can check it in your AndroidManifest.xml file in the first line in manifest tag) and click “Continue and configure services”
In this screen , you can choose the services which you want to add to enable for the application, Choose “Cloud messaging” as of now.
Okay, we are good with configuration now, Save the “Server API Key” and “Sender ID” at some place, we will need it later.
Click “Generate Configuration files”Download the “google-service.json” file by clicking on “Download google-services.json” button.
Guide to set up the Android App (Client Side) for receiving the GCM Push notifications.
Create a New Project by going to File->New->New Project and make sure to create the app with package name as you gave in last section while obtaining google-services.json
Copy google-services.json to your project’s app/ folder
Add following classpath to your project level build.gradle file
4.Add following dependency to your app level build.gradle file
5.Apply the google services plugin by adding following line at end of app level build.gradle Starcraft 2 game key generator password download.
6.Edit AndroidManifest.xml to add following permissions and Listeners
In detail, above we have added, 1 receiver and 3 services:-
GcmReceiver is the receiver that receives the downstream messages from GCM Server, when sent to this device.
permission is needed so that this receiver can receive messages that belong the package specified in category i.e.
These 3 services will be implemented in next steps, lets discuss what they are for:-
RegisterationService:- Registers our device for the first time so that we can have a token for device identity, which will be used for sending the GCM messages/notification to this device.
MyInstanceIDListenerService:- Instance ID is the token for our device that was received during registering our device at GCM Server, if the token is refreshed due to any reason this service handles the device registration once again and updating the token on our backend server.
MyGcmListenerService:- This will be our interface to all the GCM messages being redirected to our app, We can either show notifications for these messages, process them in background or perform any database operations etc.
Android Generate Aes Gcm Key West
Lets get our hands on some Java code
1.Lets create the RegisterationService.Java that serves the simple purpose of registering our application and logs a the token against which the device is registered.
2.Create MyInstanceIDListenerService.java as discussed above.
The onTokenRefresh() method re registers the application using RegistertionService.java , you may optionally update the token on your server in this part.
3.Create the MyGcmListenerService.java for receiving the Push messages.
The onMessageReceived has two arguments String “from” and Bundle “data”, data contains the payload which is sent from the server.
sendNotification() method is a simple bare bones method for displaying notifications using NotificationManager.</li> <li>Build and Launch the application using Phone or emulator, and lets test using POSTMAN which allows us making HTTP requests, or you can also send one using cURL using command line.Once you have run the application, the first thing it does is Register the device for a GCM token and Log it in console , here as shown.
Copy this token , which will be needed while sending the GCM message.Lets understand the JSON payload we are going to send to our device from server
We have in Headers the Authorization: key=<YOUR_SERVER_API_KEY> which has our API_SERVER_KEY that we got in last section while registering our app.Here “data” is the payload that will actually be transmitted to our device , we have two string in data json, the title and message that are handled in our MyGcmListenerService.java as shown in previous step.The “to” field contains the token of the device we got after device registration, which denotes where the json payload will be sent to.
Now you can make the http request using your backend server if you already have one like:-
- Use Guzzle if you are using PHP
- Use Unirest for alot of other languages
- Make request using $.post, $.ajax using jQuery.
Or if you dont have a backend yet, you can always try out using following methods.
Sending Request using POSTMAN,Assuming you have downloaded and installed POSTMAN in chrome, lets use following configuration
If all goes well you will have the notification on your device, and following response to HTTP request
Using command line (cURL)
Assuming you have CURL installed, just go to your command line and use following command
Windows
Here body.json is the file which contains the JSON payload
Linux/Mac
The device you are running on must have Google Play Services installed. (i.e. Google Play)
Aes Gcm Online
So thats it, we have the notification in our application finally after a long marathon.
This was a simple demonstration of how to get started with GCM Push notifications, you can further send messages to topics, create groups for devices etc. You can further read here.
Feel free to comment if you find this post useful or have any doubts or issues in setting this up.
Android Generate Aes Gcm Key Download
~@swarajsaaj