On Mon, 21 May 2007, Vincent Archer wrote:
I don't have (and I doubt anybody around here can) the proof to make
this a theorem, but it is a good postulate:
- It is impossible to prove the integrity of a computing system from
within the same system.
From a theoretical POV, it might be possible do it with a program
requiring all memory of the tested system (*all* memory, including memory
occupied by existing data -- whether it is possible to reconstruct them
after the fact is a different question...) to compute a correct result.
Several difficult conditions would have to be satisfied:
1. the program must be optimal, i.e. it is impossible to compute the
correct result in less space (including the space occupied by the code
of the program),
2. at some point during the computation, the contents of all memory
(including the code of the program) must have maximum Kolmogorov
complexity, i.e. it is impossible to simulate extra memory through data
compression,
3. the system must be isolated, i.e. it is impossible to simulate extra
memory through interaction with the rest of the world.
These condition might be made somewhat weaker by taking time into account
and allowing the simulation of extra memory as long as it is impossible
to do it quickly enough.
--Pavel Kankovsky aka Peak [ Boycott Microsoft--http://www.vcnet.com/bms ]
"Resistance is futile. Open your source code and prepare for assimilation."
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