General questions about TapLinx and MIFARE DESFire EV2

[Diego Palomar]

Hello guys. I have started to work with this chip recently and I have some questions. thanks in advance :)

1. When NFC is disabled the app just crashes. There are two possible cases here:

a. NFC is disabled and the user opens the app (the app was not previously opened so the process is created). The app crashes when this line is executed:
tapLinxLibInstance.registerActivity(this, BuildConfig.TAPLINX_SDK_KEY).

b. NFC was enable when the user opened the app but then disabled it. The app crashes when I put the app in the background and then again in the
foreground and when this line is executed: tapLinxLibInstance.startForeGroundDispatch()

In both cases the error is a RuntimeException so that's the reason for which the IDE doesn't suggests any possible issue for unhandled exceptions however I would expect this information to be in the JavaDoc so I can be aware about all possible exceptions. Does this mean I have to wrap all calls to the sdk into try/catch blocks (just in case)? Do you plan to release soon a new version with this part improved so I do not have to add try/catch blocks everywhere?

2. Is it possible to have a different password for each file inside the same application?

3. I'm configuring the settings for a new file using the statement in the line 3. Does the argument 'CommunicationType.Enciphered' mean that the communication between the chip and the app is encrypted or do I have to do something else to encrypt the communication?

    1. desFireEV2.createApplication(110, new EV2ApplicationKeySettings.Builder().build());

    2. desFireEV2.selectApplication(110);

    3. StdDataFileSettings fileSettings = new StdDataFileSettings(CommunicationType.Enciphered, (byte) 0xE, (byte) 0xE, (byte) 0xE, (byte) 0xE,fileData.length);

    4. desFireEV2.createFile(fileNo, fileSettings);

    

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[TapLinx Support]

Hello Diego,

As mentioned in the reply to your previous post, this has nothing to do with TapLinx. Please study the Android life cycles and the meaning of the methods onPause(), onResume(), onStop() etc. Each of the method has a purpose and limitation.

Regards,
The TapLinx team

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[Diego Palomar]

The application should not crash when NFC is disable. Of course I can wrap any call to the SDK into try/catch blocks but the SDK doesn't provide any documentation about all the possible Exceptions that could be thrown when calling either registerActivity or startForeGroundDispatch (unless you decompile the SDK and check what the exceptions are :$)

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