The War is Underway (fwd)

[David Wagner]

In article <3.0.32.19970513223226.0074e2bc at netcom13.netcom.com>,
Lucky Green  <shamrock at netcom.com> wrote:
> Contrast this with DESX, which has been
> proven to be twice as hard as DES, therefore having an effective keylength
> of 112 bits.

Actually, that's not true.  Check out the Rogaway/Kilian paper.

It says that, if you've got 2^p known plaintexts, DESX has an effective
keylength of at least 118-p bits.  So, for instance, if you've got 2^32
known plaintexts, DESX only has an effective keylength of 86 bits.

In short, 3DES is (roughly speaking) stronger than DESX.