RT1050 DCP key selection - unique key

[rtiernot]

Hello NXP Team,

I am trying to understand how key management works in the RT1050. I read the relevant chapters in the reference manuals and checked the SDK examples. I think I have almost everything figured out but I have doubts about one of the AES key options.

In the manual and examples it is clear that the DCP can perform AES-128 encryption/decryption and how to set the key and IV for it. I am interested in the OTP keys since they are stated to be unique and unreadable from SW.

I am a bit baffled about the "OTP Unique Key" option. The manual states (rather implicitly) that the OTP Block serves the 64-bit Unique Id stored in it to the DCP and then a proper 128-bit AES key is derived from it and other fuses. I have not found which fuses are those or how they should be set.

Also, if this key is derived from the Unique Id in OTP Block, which is readable, and some other fuses, which I assume are also readable, then it can not be assumed to be as secret as the "OTP Master Key" option.

Is my understanding correct? Can be this key made as secret as the OTPMK?

In that case, how should the auxiliary fuses be set?

Thank you in advance.

Regards,

Raul Tierno

[gusarambula · Accepted solution]

Hello Raul Tierno,

I have sent you a message directly. Information on these keys is available in the i.MXRT1050 Security Reference Manual, which is moderated so we cannot divulge details covered in this document on the public communities.

If you need support relating non-publicly available documents or code please feel free to open a case to request support.

Regards,
Gustavo