[Dshield] Crypto Question

[John Hardin]

On Thu, 5 Mar 2009, Valdis.Kletnieks at vt.edu wrote:

> On Thu, 05 Mar 2009 10:19:52 PST, David Brodbeck said:
>
>> To me this seems like basic "defense in depth."  Engineers would call
>> it redundancy.
>
> Which is why your programs all implement two separate 'sort' routines, 
> invoke them both, and compare the results, just in case one screws up, 
> right?

Sigh.

> Oh, you don't need to do that, because you trust the first sort routine, 
> and if it was buggy you'd just replace it, because carrying around 2 and 
> doing it twice is just a pain in the ass for no real gain? Hmm. Gotcha.
>
> Redundancy is all well and good when you're combining multiple ways of 
> doing it, each of which has a given failure rate but is presumed to 
> usually still work.  It works great if you have 2 engines each which 
> work 99% of the time.  It does *NOT* work if one engine has a 'FAILED 
> INSPECTION - DO NOT USE' sticker on it - at that point, you have *only* 
> the second engine.

Yes, but you're not dead in the water while you fix or replace the failed 
engine. How is that a failure of the redundancy model?

Valdis, I can't seem to make you see the point, I'm going to stop trying.

-- 
  John Hardin KA7OHZ                    http://www.impsec.org/~jhardin/
  jhardin at impsec.org    FALaholic #11174     pgpk -a jhardin at impsec.org
  key: 0xB8732E79 -- 2D8C 34F4 6411 F507 136C  AF76 D822 E6E6 B873 2E79
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