Master Key

[youxi]

Hello：

I have had two problems:

Is it NVM KEY after Master key is loaded?

Does ad update Master key need to know the original Master key?

[lukaszadrapa · Accepted solution]

Hi @youxi 

"Is it NVM KEY after Master key is loaded?"

- I'm sorry, I'm not sure if I can understand this question. Please try to reformulate it.

"Does ad update Master key need to know the original Master key?"

- Yes, it is required by SHE specification. You need to know the counter as well.

Regards,

Lukas

[youxi]

Hi @lukaszadrapa
The index number of the counter is from 0 to 15. what does this index number represent. and whether the super user permission is required to read the counter value.

[youxi]

This is the copied function in demo app but I can`t read the value to the counter

[lukaszadrapa]

This is something completely different.

SHE specification defines that each NVM key has a counter and it must be incremented for each update of a key. The keys can't be exported (RAM plain key is an exception) and also it is not possible to read the counter. It's up to user to know what the current counter is.

Mentioned monotonic counter is different feature. There are 16 monotonic counters (so index 0-15 is used to address them). It's not a feature related to SHE commands.

Regards,

Lukas