NTAG 413 DNA encryption

[alkhasov_i]

Hi there,

In our project we're trying to implement visit control using NXP NTAG 413 DNA.

We need the following algorithm:

User taps the tag with his mobile device. When tapped, mobile device software (which we'll develop) writes current date time to tag, and then immidiately gets it back encrypted (or CMACed). In other words, we need to encrypt or CMAC our custom data (eg. current date time) + chip UID. Is it possible to implement with NTAG 413 DNA?

Kind regards,

Igor

[alkhasov_i]

Is it possible to CMAC other data (eg. plain text) than tag UUID, counter?

[Kan_Li]

Hello,

It is possible to CMAC your custom data, you may verify with the TagXplorer as below:

Have a great day,
Kan

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[alkhasov_i]

Hi Kan, and thanks a lot for your reply.

If I understand correctly, we are able to write our custom data (e.g. timestamp) to the NDEF, and then when tapping the tag with our device (mobile phone), our custom data is CMACed and read from the tag, right?

And if so, where can I read about how to set up the tag so when tapping, it CMACs our custom data written to NDEF. Here I mean technical details.

[Kan_Li]

You may request the following docs from the doc store:

Please kindly refer to the attachment for more details.

Hope that helps,

Have a great day,
Kan

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[alkhasov_i]

Hi Kan, and thanks for yor reply.

Another question is about encryption. Is it possible to encrypt NDEF contents on the fly?

What I mean is when tapping the tag, the NDEF contents (e.g. plain text) will be encrypted and leave the tag in encrypted state (mobile device does not get the plain text, but the encrypted plain text)

[Kan_Li]

Hi I A,

Do you mean encrypting the following part by tag itself?

Please kindly clarify.

Thanks for your patience!

Have a great day,
Kan

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[alkhasov_i]

What I mean is encrypting any NDEF content (e.g PLAIN TEXT).

I do not actually understand what exactly is "mycustomdata" on the image.

[Kan_Li]

Thanks for the clarification! I am sorry NTAG 413 DNA doesn't support this, you have to use NTAG 424 DNA instead. Please refer to the following for details.

https://www.nxp.com/docs/en/application-note/AN12196.pdf 

Hope that helps,

Have a great day,
Kan

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[alkhasov_i]

Hasn't anybody faced with the kind of issue?