Re: Triple encryption...

[norm@netcom.com (Norman Hardy)]

At 00:18 1994/07/16 -0400, DAVESPARKS@delphi.com wrote:
...
>IMHO, that "middle" machine would be far more complex and expensive than the
>other two. A MITM attack might, theoretically, take only twice as long as
>attacking a single layer, the cost of doing so would be much more than twice
>as large.  Anyone care to estimate what the cost of the RAM alone for the
>"MITM interface" machine would be?  Let's see, for two 56 bit beys, you'd
>need storage for 2^57 blocks of 8 bytes each, or 2^60 bytes.  At $40 per Mb,
>or so, that would come to ... let's see ... $4 * 10^51 for memory alone.  And
>once the list of blocks started growing as the attack progressed, could the
>interface processor keep up with the other two, in real time?  Massively
>parallel processors might speed both ends of the attack, but the "database
>comparison phase" would be the real bottleneck, IMHO.
...
DAT tape, not RAM, I think. At $5 per GB I get $5*10^11 to hold the info.
MITM requires a sort of this which requires roughly log(10^20) passes with
a favorable constant. This will wear out a bunch of DAT drives but that is
relatively minor. This is about an order of magnitude bigger than a project
that I considered once to find the optimal solution to the Rubics cube.