Re: ArcotSign (was Re: Does security depend on hardware?)

[Mok-Kong Shen <mok-kong.shen@stud.uni-muenchen.de>]

Bruce Schneier wrote:
> 
> At 12:48 PM 9/22/98 +0100, Mok-Kong Shen wrote:
> >Bruce Schneier wrote:

> >> He uses a remembered secret and some mathematical magic.
> >
> >Another naive question: Why is the remembered secret not sufficient
> >(thus doing away with the magic)?
> 
> One of the significant improvements is that the scheme is immune to
> offline password guessing attacks.

If the 'mathematical magic' is not to be kept secret (as in principle
shouldn't for all crypto algorithms) then presumably one could
attack through brute forcing the 'remembered secrect', I guess.
(I suppose the 'remembered secret' has less bits then the 'password'
that is to be retrieved from the pool of millions with the
'mathematical magic'). So the advantages of the scheme appear to
remain unclear as a matter of principle.

M. K. Shen