Forum › MIFARE SDK › Problem authenticating a MIFARE Ultralight EV1 tag › Reply To: Problem authenticating a MIFARE Ultralight EV1 tag
Hello Jorge,
I had a discussion with the development team and with “Ultralight EV1 experts”. The tag replies a NAK only in the case if the password is correct, but other things are wrong, e.g.: wrong CRC. If the password is incorrect, the tag never reply anything! This is an intended behavior to hinder attacks.
Table 10 on page 21 list return values 6, 9 with “NAK, other error”. I assumed, an invalid password is one of the NAK reasons. Now it is clear, this is wrong. The datasheet will be changed soon.
For an invalid password the software runs always into a time out, which is at the end a “tag lost exception”. So you have to handle this case in software.
Thanks for the valuable feedback,
The Taplinx team
I had a discussion with the development team and with “Ultralight EV1 experts”. The tag replies a NAK only in the case if the password is correct, but other things are wrong, e.g.: wrong CRC. If the password is incorrect, the tag never reply anything! This is an intended behavior to hinder attacks.
Table 10 on page 21 list return values 6, 9 with “NAK, other error”. I assumed, an invalid password is one of the NAK reasons. Now it is clear, this is wrong. The datasheet will be changed soon.
For an invalid password the software runs always into a time out, which is at the end a “tag lost exception”. So you have to handle this case in software.
Thanks for the valuable feedback,
The Taplinx team
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