Re: Breaking DES

[doug@netcom.com (Doug Merritt)]

> pmetzger@lehman.com said:
>Doug Merritt says:
>> 2^56 bytes equals 10^7 gigabytes.
>
>First off, you are forgetting a factor of eight.

No, I'm not. I *am* assuming disk, obviously, since I quoted $1000 per
gigabyte, which is disk price range, not RAM.

> and if you use disk storage your whole device is going
>to run far, far, far slower.

Untrue. The disks will be used in a predictably serial fashion, and therefore
read-ahead can be arranged such that everything is in RAM by the time
the algorithm is ready to use it, so the whole thing runs at RAM speeds.

>however, and have to factor in the cost of the rest of the equipment,
>like power supplies, enclosures, controller cards, computers to run
>the whole thing, I'd say we are talking a trillion dollars, give or
>take a factor of 20%.

It's true I didn't factor in the cost of the systems, but that doesn't
give more than a factor of 2 to 5 in cost (depending on assumptions about
the precise kind of pc clone used), where you seem to have come up
with a factor of 100.

>> Or say there's a quantity discount in orders totalling a million
>> units,
>
>Say that my aunt was a Greyhound Bus if you like. You're dreaming, bub.

Skip the sarcasm and pick a different quantity discount. If you don't
like my 90% discount for quantity 1 million disk drives, pick another
one. There is always some discount for quantity, and this is just a back
of the envelope estimate, so I don't care much what you pick. 0% discount
leaves the estimate in the region of $10 billion...that's still not
inconceivable, merely expensive.

That was my only point, that this *could* be done, and I've proven that,
despite your misunderstandings.
	Doug