🚀 go-pugleaf

Mark Wooding wrote:

> Peter Howkins <p.j.howkins@lboro.ac.uk> wrote:
>
> > Erm, PGP uses IDEA. Blowfish is partially susceptable to differential
> > cryptanalysis (at reduced rounds). IDEA is probably the best bet,
> > though
>
> There have been no results at all against the full Blowfish cipher[1].  The
> only result I'm aware of is that a class of `weak' keys can be detected
> in reduced-round variants.  The weak keys can be tested for and rejected
> if you're worried about them: they're not very numerous.
>
> Then again, Daemen found a class of weak IDEA keys, and Borst, Knudsen
> and Rijmen have demonstrated truncated differential and differential-
> linear attacks against reduced-round variants of IDEA (see `Two attacks
> on reduced IDEA'[2]).
>
> I'd rather trust Blowfish than IDEA right now.
>

You could well be right, I was half remembering something I read in Schnier's
book'applied cryptography' where he critiques his own cipher, by saying that it
had a
problem at reduced rounds. I thought it diff-cryptanalysis though it could well
be weak
keys.

> [1] Results from Lars Knudsen's `block cipher lounge':
>     http://www.ii.uib.no/~larsr/bc.html.
>
> [2] An extended abstract of this paper may be found at
>     ftp://ftp.esat.kuleuven.ac.be/pub/COSIC/rijmen/idea.ps.gz.
>

I shall have to look at these when I get a chance.

Peter
--
p.j.howkins@lboro.ac.uk