android-pn532-hce

Python NFC example for PN532 to receive a unique id (uid) of an android device or simple nfc tags (for auth, whatever).

Concept

For deeper info check this link by Mohamed Hamdaoui. He communicated between two phones, some of the android code is used from him: https://medium.com/the-almanac/how-to-build-a-simple-smart-card-emulator-reader-for-android-7975fae4040f

tl;dr

Default: Card Reader sends APDU (Application Protocol Data Unit Command) -> tag will respond with uid. Issue: Android device responds with either '01020304' or different id every time you hold it to the reader. Solution: Android allows Host-based Card Emulation (HCE), so it may behave like a simple nfc tag / smart card. It can take APDU commands and return APDU responses.

Installing the android app will register an APDU service with an AID (in this example 'A0000001020304'). The reader (PN532) sends an APDU command containing this AID, the android device executes our registered service and sends back a local generated unique id (stored/persistent). No need to run the app after installation, service will do the job in background. Device can be locked, but screen needs to be on (android security policy).

PN532

This is running on my Pi. The PN532 board needs to be connected via UART (because i2c / spi is not supported by nfcpy lib which will be used). Check some tutorials for this, if you haven't connected it yet. In this example libnfc is not neccessary.

Install & Run

install pip3 if not installed:

sudo apt-get install python3-pip

install nfcpy:

pip3 install -U nfcpy

Clone this repository:

git clone https://github.com/Lexycon/android-pn532-hce.git
cd android-pn532-hce

And finally run the main.py file. It's an example how to use the PN532.py class.

python3 main.py

Android

Either build this whole project by your own or use the prebuilt apk: releases

Copy the apk file to the phone and install it. The UI shows the generated uid. Delete application data to get a new id.