IDEA (was: Re: Decryption problem)

[Johan Wevers]

Robert Fendt wrote:

> The use by a "private individual" for "non-commercial purposes" is, by my
> understanding, free.

Well, I use it mostly in communications I don't want the Scientology cult to
read, which are non-commercial.

> Nevertheless, this stands in direct contrast to the GPL;
> so, IDEA cannot be incorporated into GnuPG.

Not directly that is.
 
> This brings me to an interesting question: one of the two algorithms'
> patents (RSA and IDEA) ends somewhere in 2001,

The RSA patent ends on September 20, 2000 (according to thr rsc.c gpg module).
I don't when the IDEA patent ends.

> And: how specific are these patents anyway? Would it be possible to create
> a different cipher based on the same mathematical principle (and therefore
> with comparable qualities) without breaking a patent? After all, RSA is
> faster than DH, and IDEA has undergone extensive analysis.

That would require a thourough analyses of those tweaked algorithms by
cryptographers. And because IDEA and RSA have survived this without having
shown any serious weaknesses they are trusted algorithms. But a small change
can completely destroy their security.
 
-- 
ir. J.C.A. Wevers         //  Physics and science fiction site:
johanw@vulcan.xs4all.nl   //  http://www.xs4all.nl/~johanw/index.html
Finger johanw@xs4all.nl for my PGP public key.  PGP-KeyID: 0xD42F80B1