DES

Two questions about DES. 

1) If the current, 56 bit, DES system is so easy to break why don't people
switch over to a DES system that uses a larger key space, say 128 bits?
People obviously aren't, so what's the barrier to this? 

2) How much longer would it take to break triple DES versus standard DES
using one of the key-breaking machines described? 

	As an aside I'll point out that I go by the Yakima Research Station once a
month when I'm out with my National Guard unit, this is the radio dish
that's on the cover of _The Puzzle Palace_. It's not a very large
installation.



Jamie Jamison
niteowl@u.washington.edu

Jamie Jamison says:
> 
> Two questions about DES. 
> 
> 1) If the current, 56 bit, DES system is so easy to break why don't people
> switch over to a DES system that uses a larger key space, say 128 bits?
> People obviously aren't, so what's the barrier to this? 

DES only takes 56 bit keys.

> 2) How much longer would it take to break triple DES versus standard DES
> using one of the key-breaking machines described? 

Using brute force, it would take the cube of the time it takes to break
single DES. Whether a more sophisticated techinque is possible is unknown.

Perry

Jamie Jamison <jamie@apl.washington.edu> wrote:

> Two questions about DES. 
>
> 1) If the current, 56 bit, DES system is so easy to break why don't people
> switch over to a DES system that uses a larger key space, say 128 bits?
> People obviously aren't, so what's the barrier to this?

It's not easy to break.  It is possible to break it with about $1
million worth of specialized computing hardware.  Many programs, such as
PGP, do use larger keys.

> 2) How much longer would it take to break triple DES versus standard DES
> using one of the key-breaking machines described?

If all combinations had to be tried, it would take 2^112 times longer to
break a triple DES (168 bit) code than to break the standard 56 bit code.