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CESc question

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Contributor III

Dear all,

   1. whether can  i  get the key  value by software ,such as  MASTER_ECU_KEY/BOOT_MAC_KEY/BOOT_MAC, KEY_<n> ,  RAM_KEY?

   2.whether MASTER_ECU_KEY is 128 bits  1 when i  get one new ecu? 

   3. if I update MASTER_ECU_KEY after I get one new ecu, but after long time I forget the  new MASTER_ECU_KEY which last time updated,  at this time how can i update MASTER_ECU_KEY and other key, and how to do it?

   4. whether RAM key  save in NVM? if yes, why after reset, RAM_KEY became empty?  

wish your hep, thanks  very much!!

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jorge_a_vazquez
NXP Employee
NXP Employee

Hi kui wu

whether can  i  get the key  value by software ,such as  MASTER_ECU_KEY/BOOT_MAC_KEY/BOOT_MAC, KEY_<n> ,  RAM_KEY?

Those Keys are defined by the user, so you should know them before have them programmed.

whether MASTER_ECU_KEY is 128 bits  1 when i  get one new ecu? 

For a blank key, the key being updated has an initial value of “all 1s”.

if I update MASTER_ECU_KEY after I get one new ecu, but after long time I forget the  new MASTER_ECU_KEY which last time updated,  at this time how can i update MASTER_ECU_KEY and other key, and how to do it?

If you don't have the Master key, then you will not be able to update any other key, this MASTER_ECU_KEY is the only one that can update any other key.

whether RAM key  save in NVM? if yes, why after reset, RAM_KEY became empty?  

RAM_KEY is not saved in NVM, it is a volatile key and can be used for any arbitrary operations.

I recommend you check the application note AN5401:

https://www.nxp.com/webapp/Download?colCode=AN5401 

Hope this info could help you.

Best regards

Jorge Alcala

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