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johnnyb / ntag424-java

A Java library for the NXP NTAG 424 DNA chip
MIT License
21 stars 3 forks source link

GetFileSettings needs to run in Non Authenticated state #3

Closed johnnyb closed 5 months ago

johnnyb commented 7 months ago

GetFileSettings needs to run in Non Authenticated state

[Submitted via email by AndroidCrypto]

johnnyb commented 7 months ago

The table on pg. 44 indicates it should run in MAC mode, which implies an authenticated state, but I will look into it (and maybe other commands that may not need authentication).

MichaelsPlayground commented 6 months ago

There is another rule "overriding" the data on pg. 44 - see "8.2.3.5 Communication modes": Page 14: "If there is no active authentication, the command and response are sent in plain (or the command is rejected in the case an authentication is required)".

It is important for a NFC reader to get the FileSettings without authentication, because the GetFileSettings response defines which key has to be used for e.g. a read access.

johnnyb commented 5 months ago

Interesting! I didn't realize that it had that exception. I now have nxpMacCommand and nxpEncryptedCommand short-circuiting to nxpPlainCommand if !isLoggedIn(). Commit 6a8b94a.

AndroidCrypto commented 5 months ago

Confirmed, solution is working, thank you. Greetings Michael