Wouldn't the other reason to have multiple manufacturer keys, be to guard against them losing the private key for one in a way that means they can't sign anything any more?
I mean, sure, but to what end does that madness lead? Who backs up the backups?
Usually this is to allow different departments / divisions / customers (in the case of an OEM model) to all sign code or encrypt binaries, although this is likewise a bit off as each enrolled key increases the amount of material which is available to leak in the leak model. Or to allow model line differentiation with crossover.
Comments
Wouldn't the other reason to have multiple manufacturer keys, be to guard against them losing the private key for one in a way that means they can't sign anything any more?
I mean, sure, but to what end does that madness lead? Who backs up the backups?
Usually this is to allow different departments / divisions / customers (in the case of an OEM model) to all sign code or encrypt binaries, although this is likewise a bit off as each enrolled key increases the amount of material which is available to leak in the leak model. Or to allow model line differentiation with crossover.