🚀 go-pugleaf

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.


[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.

-- [mdw]