Programmer's Notebook

A LAN server discovery web app Table of Contents Requirement Next movement how to deploy the service? 1 Requirement the purpose of this project: Many services were running in my desktop environment at the company LAN, but the IP address was always alternate after I reboot, so my initial intent to develop this app is to let my fellow colleagues detect my desktop's IP address much quickly. this solution is to run a HTTP server on my desktop, and the client must post request at least with a key/value pair: req=get_ip. Then a client scan all the LAN IP address with that request, my computer will response with {'status' : 0, 'ret':ip_address}. 2 Next movement Since I am studied a lot of certification and encryption knowledge recently, I guess the next target of this project is to add a certificate process to reject the fake one. The simple ways were to employ an asymmetry encryption algorithm like RSA, then client generate a random number...

Android's Package Management System Table of Contents How to resign an android app? How to install an android apk? android package management system. How to get an app's certification? 1 How to resign an android app? Android apk's digital signature strategy just employs the java's jar package method. So We can use java's keystore and jarsigner tools to sign an apk. And the first step is to generate a valid certification: make your own keystore keytool -genkey -v -keystore iboxpay.keystore -alias ibox -keyalg RSA -keysize 2048 -validity 100000 please remember the store password and key password, I always set them the same one. then before to resign an apk, I should remove its original signature first. remove apk's digital signature zip -d whatever.apk "META-INF/*" After that, I can sign that apk by our own certification. sign apk by jarsigner jarsigner -verbose -keystore iboxpay.keystore -storepass 123456 what...

Reverse Engineering Android apk Table of Contents Background Apktool dex2jar + JD-GUI 1 Background Here is my puzzle at this moment, my superior gave me a task to make Bluetooth Low Energy product which includes Android APP part, but there are no virtual designer and product manager, just myself as a software engineer. So, my first step is to found out a similar product and refer its design. Then, I need to decompile that app, some reverse engineering skills of Android app and java are necessary. I guess following two methods are enough to decompile an Android app. 2 Apktool ApkTool is a tool for reverse engineering Android apps, what it is pretty good at is to decode resources to nearly original form and rebuild them after some modification. But the java code part is decompiled into the smali format, which is not a good format to read and understand. 3 dex2jar + JD-GUI Apktool can not generate readable java source code, actually, there are no re...

Android APP development team composition Table of Contents Android APP team Exploration Stage Team Structure Acceleration Stage Team Structure Innovation Stage Team Structure 1 Android APP team Recently I have a job to develop an Android APP, this one is not a toy app anymore, it is a serious product. In the former time, When the superior dispatch an app task to me, most of the time, I did not worry about the user interface or UI design, I just need to finish the job by my way, just ignore the ugly interface, because most of the jobs are just test or research oriented. But this time is different, I need to develop a serious product. How can I make a product by myself? So I try to figure out the quality of the good team to make an awesome app. Then I found the following link to answer my question: http://www.slideshare.net/Mutual_Mobile/maturing-your-mobile-development-team This article provided three stages of Team structure, which can be a reference to ru...

Light BLE APP Table of Contents What is Light BLE APP? The Advantage of this APP Why I make above improvement? Source Code 1 What is Light BLE APP? It is an enhanced android app to communicate with Bluetooth LE peripheral. This app may be useful in Bluetooth Low Energy peripheral equipment development. It is based on an example in Android's SDK source code sample which located in sdk/samples/android-19/connectivity/BluetoothLeGatt/ , but that example sucks(yeah, Light BLE  sucks too, but much better than that sample). 2 The Advantage of this APP Following is what I improved based on that sample. Change the LocalService and Activity communication mechanism from broadcast intent into callback hooks. Add RSSI signal detects. Add write characteristic dialog(still need to improve). 3 Why I make above improvement? Broadcast Intents was not dependable, I guess that's the reason that I missed a lot of messages. So I studied the communicat...

How to write Android Service? Table of Contents Two kinds of Services in Android Local Service Remote Service Broadcast 1 Two kinds of Services in Android When we wanna make an Android app, we should put the time-consuming jobs into a service, actually, there are two kinds of services in Android, Local Service, and Remote Service. The difference between them is that whether they are running in the same process as the app, the local Services are running in the same process as the app, while the remote Services are running in the separate process, and I just need to add the following attribute to the AndroidManifest declaration to announce a remote service, it is a local Service without this attribute. android:process=":remote" After We build the Service, We need to communicate with this object, send a message to Service is obvious, I just need to bind to that Service. But how to receive announcement and messages from the Service, the mechanisms to do ...

How to setup an NAT server? Table of Contents What is NAT? How to setup NAT host? a shell script from vbird's book 1 What is NAT? NAT stands for Network Address Transition, which is the basic function of gateway host. I try to hack Bluetooth tethering module in android this week, it include the Bluetooth Pan profile and the NAT setup process, which means in order to implement the Bluetooth tethering, first, two devices must be connected by Bluetooth Pan profile, and then the server part device acted as gateway host to supply the network forward service. In other words, after Bluetooth Pan profile connected, the server must to setup its NAT rules to forward the IP packages. So how to setup NAT rules? 2 How to setup NAT host? My memory is still fresh that at the start of my Linux journey, I setup my Linux desktop as an NAT host to provide Internet services for my lab's classmates. During the days as a programmer, I once did a job to hacking android...