How to store android application data on sim card using NFC?
I am developing a NFC application. My application will process secret information and I want to store that data on the SIM card. Is it possible, and if it is possible, how can I do this? My phone's android version is Android 2.3.5.
Answer
tl;dr - it is not currently possible without enormous effort.
You want to use the SIM card as the Secure Element in Card Emulation mode - this is the approach favoured by GSM Association. To access the Secure Element (on SIM or Integrated Chip), you need to use a Trusted Service Manager (TSM). In your case, the TSM would send data to your SIM card using binary SMS messages. The problem is that it is very early days for NFC on mobile phones. Tag reading/writing is simple enough but accessing the Secure Element is not. There are very limited trials of NFC SmartPhones using SIM as secure element for Card Emulation, and the trials are all currently limited to a specific Mobile Network Operator (MNO) in specific countries.
If you do want to do this, you need to read the specifications, write a TSM and then get the necessary contracts with the MNOs to be allowed to use their SIMs.
Good luck!