[Cryptography] Usable Security Based On Sufficient Endpoint-Specific Unpredictability

[Ralf Senderek]

On Sun, 11 Oct 2015 18:39:30 natanael writes:

quoting me:
>> Malware that has got read access as the root user could read any file or
>> information on the endpoint device, but as the production of the password
>> requires execute permission, all secret information secured with this
>> password is still safe until execute permission is gained.
>
>Nope, impossible. With access to all secrets, there's no capabilities the
>malware lacks as it runs in a Turing complete environment

Not all malware runs in a Turing complete environment. You're mistakenly 
thinking of all attack scenarios as happening inside one big computer.
It's much more likely that a network attacker gets access to information
she shouldn't be able to read by feeding malformed packets to daemon
processes over the network, or .. or .. without getting complete control
over the target machine. The world is not binary and there are increasingly
more ways to make bad use of the complexities in which the user's endpoint
device interacts with the rest of its network environment that may
in part be controlled or abused by a network attacker.

       --ralf