On Wed, March 21, 2007 16:50, Tasos Parisinos wrote:I really can't comment more on these... you understand that in that case i would give away some interesting
A malicious person may want to alter code on the detachable (and unsafe)
file system.
Lots of stuff including the kernel will be in a trapped casing (opening,
probing it, power
analyzing it, heating it etc will result in system suicide and erasure)
What happens ift he whole thing is cooled so much that it stops functioning?
What if the part that is supposed to do the system suicide is shot away?
There are all kind of interesting ways of bypassing such protections, I
wouldn't count on covering all of them (which doesn't mean you shouldn't try).
it would be a mess to do desent key managementIf one alters one device then he can go on and play with it at home
But if one finds the key that authenticates the executable code it will
be possible to
attack and tamper the non-system software on some of the networked devices
That is why we can't use symmetric, the risk is a lot greater there. And
of course
we cant have one key per device (maybe thousands)
How many devices there are doesn't matter, a RSA key is ten times as big
as an AES key anyway. But maybe you've a more complex system where having
multiple keys indeed isn't possible (e.g. the filesystem is shared between
multiple devices).
RAM will be restricted, we try to do the best we can on filesystem.You are not going to check all at once but only on load. I tell you
again this is
not going to be running as a web server, but in a restricted environment
Well, as the filesystem isn't restricted you should be prepared for anything.
Is the RAM in restricted area or not? Because if it isn't and they have
access to the bus then it can be tampered with.
Well in our design the most HOT data will be inside chips that you need serious equipment (and money)As for the code bloat and complexity... well you know its up to u to use
it or leave it
dont include where you don't need it.
I mean we created for our specific use, other may want to use it to
(maybe for
the same reasons, who knows) why not make it available? Isn't that what
open source
is about?
And on the bottom line, why not have a module and functionality that Linux
competitors provide and advertise?
I've nothing against your RSA implementation, it's one of the cleaner and
smaller ones. Merging it is probably a good idea to stop others and to have
a minimalistic reference implementation.
I've problems with the assumed security it brings to many uses of it though.
Depending on the expected lifetime of your product I'd also consider using
something that can't be broken by quantum computers in the (near?) future. ;-)
Good luck,
Indan