RSA / DSS (keylenghts)

[Ralf Senderek]

On Thu, 21 Sep 2000, Simpson, Sam wrote:

> For a start:  Elgamal keys are (currently thought to be...) stronger than
> RSA keys of the same size?
> 
> (see for example: http://www.scramdisk.clara.net/pgpfaq.html#SubRSADH).
> 
> 
> Regards,
> 
> Sam Simpson
> http://www.scramdisk.clara.net/


If you double the size of a RSA-modulus (i.e from 512 Bit to 1024 Bit)
there is a huge amount of possible new secret key values (factor 2^512)

BUT:

if you double the size of a DSS-key not one additional secret key value
is added because the amount of possible secret keys is limited by the
size of the hash-function (160 bits), Only the mathematical operation 
will use a longer key (as modulus) and consequently takes more time.

Ralf Senderek


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