Asymmetric Key sizes

[Paul Leyland]

> Although a lot is being said about the shrinking level of 
> security offered
> by various symmetric key sizes, with 56 bits coming in for a 
> lot of stick,
> haven't seen anything lately on asymmetric attacks. Has anyone any
> information on the latest successful attack position on 
> asymmetric keys, RSA
> in particular? How secure is 512 bits considered now, and 
> why? What's the
> current recommended key size? Has anything been published 
> that is later than
> the now rather old (January 1996) "Report by the Ad Hoc Group of
> Cryptographers and Computer Scientists"?


The world record factorization is now 463 bits.  See, for example,
http://listserv.nodak.edu/scripts/wa.exe?A2=ind9902&L=nmbrthry&F=&S=&P=302


512 bits is looking decidedly shaky IMAO.

Paul