Android: Mobile Recharge via SIM Toolkit

Question

Im developing an android application for my client. My client is a SIM card distributor in our location. My client wants to access SIM card toolkit to recharge mobile. I dont have any idea how to do it? Can anyone guide me in right direction.

Network: Airtel

I need to access Airtel SIM toolkit via my android application to recharge.

Answer 1

You can use STK service from platform packages. Take a look over the source of STK App that comes default with android. https://github.com/android/platform_packages_apps_stk
An old documentation over this app can be found here http://www.kandroid.org/online-pdk/guide/stk.html

Answer 2

If primary account number is planned to store in Android application, bear in the mind that still some of most used Android phones do not have Secure Element chips. Option could be using SIM as secure element by Android application. As far as I know Android Open Source Project does not define an API to use the SIM card as a secure elements, but as long as the device baseband and RIL support, SEEK for Android patches can be added. If it is possible obtain SIM profile and OTA keys, custom STK Toolkit applet can be developed and installed on the SIM via OTA.

STK menu application can provide required user interface to receive inputs. All key management, encryption logic and integrity of encrypted data should be achieved and implemented inside the SIM as Secure Element . Public key cryptography is typically not implemented by SIM cards for mobile network authentication or OTA secure data. That's why available option is to use secure symmetric and hash algorithms. If EMV certification is required, it is better to consult local partner after learning supported encryption algorithms on SIM cards of MNO.