What meta-data can I pull from a 9160 delta modem update.bin file?

[Mathew Calmer]

Hello!

I'm implementing a 9160 modem update system in our application.  I'd like to be able to do some verification steps on my file prior to commencing the update.  Ideally this would include verifying the file:

• is a legitimate delta file and is uncorrupted (performed by modem)
• is targeting the correct firmware base (performed by modem)
• is not too large to fit in the scratch (I can do this much prior to the update)
• is an update to the firmware version I intend 

As far as I can tell, the modem performs some of these actions (as noted) but I would ideally perform all of them before even beginning an update.  

Besides the MODEM_MAGIC and the filesize, is there any other meta-data available to me in a modem_update.bin file as provided by nordic?

Thank you.

[Didrik Rokhaug]

Hi,

I had to check this with our modem team, and this is the reply I got:

• Only the modem can decrypt, authenticate and integrity check the delta image.
  • Offline operation is not possible.
  • The modem will respond with a failure response as early in the download process as possible, so if e.g. data is corrupted in transit, it will be detected by the modem no later than after 8 kBytes of additional data has been transferred.
• The modem will verify that the delta image targets the on-board firmware during the transfer of the first 8 kBytes.
• It is the responsibility of the infrastructure outside the modem to pass the correct delta image to the modem.
• The delta update area in the modem is not used for any other purpose, so for each firmware release, we know how much scratch area there is in all devices with that firmware release. Our modem firmware build process cannot generate a delta image that would not fit.

Best regards,

Didrik

P.S. I will be out-of-office tomorrow, so I will not be able to provide further replies until Monday. Sorry for the inconvenience.