Slashdot | 3D Microfluid Computers Used To Solve NP Problems

[Ray Dillinger]

On Sat, 24 Mar 2001, Jim Choate wrote:

>http://slashdot.org/articles/01/03/24/1840252.shtml


Cryptographically interesting.  It looks like starting now, 
the highest-end threat facing a cryptosystem involves liters 
of fluid performing molecular computation. 

The kick is that these molecular computers aren't all that hard 
to design and they scale.  Which means someone can have a 
1000-liter computer with somewhere near the same ease they 
can set up a milliliter computer. 

So we need to revise the recommended key lengths for security
purposes.  There are about 2^167 atoms in planet earth, 
about 2^30 nanoseconds per second, and 2^39 seconds till the 
next ice age.  So, if a tenth of that mass were made into 
ten-atom computing units that could complete a calculation 
every ten nanoseconds, I get about 2^226 operations before 
the next ice age.  Assuming each is a brute-force check, 
we should probably be looking at symmetric ciphers with 
keys a minimum of 225 bits long right about now. Round up 
to the nearest handy power of 2 and make it 256 bit keys. 

Fortunately, the AES, and several other recent symmetric 
ciphers, have a use for a 256 bit key. 

Unless they find some radical flaw in AES & Co, I don't see 
a real problem posed by molecular computing; we just need 
to start taking it into account when we decide what key 
length to use. 

				Bear