🚀 go-pugleaf

In article <1hcp41INNdi4@rave.larc.nasa.gov> palmer@icat.larc.nasa.gov (Michael T. Palmer) writes:
>What size key does IDEA use?  Is the length sufficient to stand up against
>brute force attacks?  I mean, if you can brute force it then why bother
>encrypting the session key with RSA (as in PGP and RIPEM)?  Nobody has to
>worry about the public key stuff, they can just go right after the plain
>text.
>
>Since I've seen here that IDEA might end up in an update of RIPEM, I was
>just wondering if it offered more security than DES (in CBC mode).  Please,
>forgo the legal asides concerning the algorithms and respective export or
>patent laws.  I'm just interested in what key sizes the different ciphers
>use.

IDEA uses a 128-bit key, compared to DES's 56-bit key.  There isn't time
left before the heat death of the universe to mount a brute-force attack
against IDEA.

Now, for the caveat.  IDEA is still a new algorithm.  It is possible that 
there is an attack against the algorithm that is significantly better than
brute force.  Several academic institutions, and the militaries of several
countries, are examining the algorithm.  So far no one has found anything,
or at least no one has publicly admitted to finding anything.  IDEA looks
real good, but it's too soon to make any confident statements.

I am more confident with triple-DES (112-bit key), but that takes a whole
lot longer than IDEA.

Bruce