Mifare Ultralight authentification using android

Question

I am creating an android app that stores some user data on NTAG203 tags.

Is there a way we can write a password to the tag and read back the data only when supplied with the password?

Answer 1

No, its not possible to implement any form of password-based authentication with NTAG203 or MIFARE Ultralight (MF0ICU1) tags. Those are simple memory tags without any cryptographic functionality. You can only set lock bits that (permanently) lock access to data (one lock bit per page and additional lock bits to lock the lock bits).

Depending on your requirements, it might be possible for you to encrypt the data before writing it to the tag (and decrypting the data after reading it from the tag) using a password.

Besides that, other tags in the MIFARE Ultralight and NTAG series have support for a very limited (and not really secure) form of password protection.