bitstream update with non-volatile key programmed

Thanks for your answer,

i understand that the .ekp file is a needed part of the secure design flow but, as the document is not so clear about this point, i wonder if the key programming file (.ekp) is, as the name suggests, just the key file to be written to the FPGA? if such a key is the same as the user key, used to generate the encrypted jic file, i assume that any bitstream encrypted with the user key should be fine and get decrypted by the secure core. This would allow a scenario where if you have a device "in the wild" you can protected and also have the ability to update its design when its needed.

I am aware that the volatile key might fit well in this situation but we are working on a pre-existing hardware that dosen't provide a battery for retaining the encryption key in the volatile memory. That is way we are forced to use the non-volatile approach if we were to provide any security for our design but we don't want to lose the possibility to push new updates to the design and extend its functionality once the secure flow is in place.

Is there are any suggestions that you can provide regarding this matter ?

Thanks