Tiered Firmware Features

I posted this earlier, but I believe it may have been discarded due to the subject heading. Several key words in it could have confused an automated script to discard it as junk. Crossing my fingers that I don't double post here...

I am developing a widget. Management wants me to structure the firmware in such a way that the widget has a few tiers of functionality. The functionality is all enabled in firmware. So for example a user may purchase the base unit and then decide at a later date to upgrade to a second or third tier of functionality. The idea is to provide a unique key to unlock the features.

I have the idea to relate the key to the serial number of the widget. This takes care of the unique aspect preventing the key from being applied to other widgets that have not been upgraded. So, the user enters the key and it's hashed against the serial number to produce a bit field which indicates what features are to be enabled.

Any suggestions as to an alternate approach? Or perhaps a robust method to produce the desired result from a key and device serial number?

Reply to
eeboy
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Your post certainly made it through this time. Your concept sounds good, but I don't have any better solutions for you.

Scott

Reply to
Not Really Me

o

The method you have described is one common method. Another method is for the device to generate a random challenge and decrypt a response provided by your unlocker. This avoids the need for serializing the device's firmware.

Reply to
larwe

o

How about FCS32 of the two? Mind you, I have *never* done that, just recently handled ethernet address hashing which was done this way and thought it might be an idea...

Dimiter

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Dimiter Popoff

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