topic Re: Configuring SE to be fully functional but rejecting attempts to add more secure objects in Secure Authentication

Configuring SE to be fully functional but rejecting attempts to add more secure objects

psvz — Thu, 08 May 2025 22:27:45 GMT

Is it possible to lock SE051H in a state where it would be fully functional but reject attempts to add more secure objects?

Background. If I provisioned a factory-reset user and other secure objects with policy not allowing deletion or modification - I am fine to deploy the chip to untrusted environment to operate reliably.

An adversary, however, can provision thousands dummy secure objects to consume all memory. That might affect reliability of the SE operations. Could you please confirm if such scenario is a threat? And if so, how could I mitigate?

Re: Configuring SE to be fully functional but rejecting attempts to add more secure objects

Kan_Li — Fri, 09 May 2025 05:42:10 GMT

Hi @psvz ,

There is an APDU command available on SE051 parts for that purpose. Please kindly refer to the following for details.

You may refer to https://www.nxp.com/webapp/Download?colCode=AN12543 for more details.

Hope that helps,

Have a great day,
Kan

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Re: Configuring SE to be fully functional but rejecting attempts to add more secure objects

psvz — Sat, 10 May 2025 15:03:16 GMT

Hi @Kan_Li

Thanks for pointing me out to the sought APDU command. I can't find any middleware API for it - I checked all Se05x_API* functions. What is the shortest way to activate that APDU command in C? If middleware doesn't support it, perhaps you could kindly share a code sample?

Re: Configuring SE to be fully functional but rejecting attempts to add more secure objects

Kan_Li — Tue, 13 May 2025 05:40:25 GMT

Hi @psvz ,

Please kindly refer to Se05x_API_DisableObjCreation() for details.

Have a great day,
Kan

Re: Configuring SE to be fully functional but rejecting attempts to add more secure objects

psvz — Tue, 13 May 2025 12:53:47 GMT

Hi @Kan_Li ,

Thanks, I was searching in

simw-top/hostlib/hostLib/se05x_03_xx_xx/se05x_APDU_apis.h

and overlooked additional `se05x_04_xx_APDU_apis.h` file there...

Provided I use LOCK_PERSISTENT and RESTRICT_NEW combination (I rely on creation policy for objects I provisioned before this command), what is behavior if then call Se05x_API_DeleteAll() command?

Will the factory reset cancel this persistent lock? Or will I throw the chip into garbage after restricting and then resetting?

Re: Configuring SE to be fully functional but rejecting attempts to add more secure objects

Kan_Li — Thu, 15 May 2025 08:41:18 GMT

Hi @psvz ,

Even in this case, the factory reset would not cancel this persistent lock.

Have a great day,
Kan