[Cryptography] Caches considered harmful

[Ray Dillinger]

On 01/11/2018 07:11 AM, Kent Borg wrote:

> 
> -kb, the Kent who wants autopilots and MRI machines and cryptography
> programs and mortgage balances and door locks to be doggedly predictable.


I'm with you on that, but there is a caveat.

Autopilots in particular, if too predictable, are open to attacks
against herds of cars resulting in massive traffic jams etc, which are
non-issues if they are individually somewhat probabilistic.

More generally, in dealing with chaotic systems, dogged predictability
is no advantage.

Cryptography, mortgage balances, and door locks have simple input and
simple requirements.  Dogged predictability is exactly correct.

MRI machines and autopilots interact with chaotic systems.  In the
absence of any possibility of predictable input, there is no advantage
that can be shown for predictable vs. probabilistic behavior - both are
approximations. Predictable can't be made to fail less often, nor made
reliable more easily, than unpredictable.


				Bear

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