RE: Counter Mode Security: Attacks, Storage & a Proposal

[Black_David@emc.com]

Responding to Paul's two observations on my post ...

> I'm also somewhat hesitant to argue about your storage cost numbers,
> but still, two observations...  
> 
> 1. As I recall, the historical rate of capacity growth has not been
> all that constant (unlike, say, the Moore's Law analog in processing
> power).  Not all that many years ago the rate increased dramatically,
> I believe.

I believe that's correct, and "doubles about annually" is the new
"dramatically" increased rate.  The better part of a decade ago,
progress on disk media density was sufficiently slow that it looked
like DRAM might start seriously encroaching on disk space.  Some
physicists/materials scientists got seriously annoyed about this,
and the results are now obvious ...

> 2. The analysis assumes that hard drives are and continue to be the
> most cost effective (YB/$) technology.  I'm not sure that's true now
> (consider tape libraries) and it may not be true later.

As Ted pointed out, tape libraries are an obvious non-starter for this
sort of attack, although a cut down version of the attack computation
might make a nice tape drive and robot abuse test ;-) .

One can indeed speculate about new storage technologies coming along -
one could also speculate about the quantum computer folks succeeding
and rendering entire classes of complexity analyses obsolete.

Thanks,
--David
----------------------------------------------------
David L. Black, Senior Technologist
EMC Corporation, 176 South St., Hopkinton, MA  01748
+1 (508) 293-7953 **NEW**     FAX: +1 (508) 293-7786
black_david@emc.com        Mobile: +1 (978) 394-7754
----------------------------------------------------