Re: Closing on shared-key authentication

> 
> The lack of a general extension mechanism in SSL v3 is a feature, not a
> bug.  This is a security protocol, and so susceptibility to analysis is
> a good thing.  Simplicity and rigidity are features here.  SSL does
> provide for forwards compatibility by allowing version negotiation and
> protection from version rollback attacks.
> 

I must take exception here - not with the advantages of making security
protocols easy to analyse, but with the implicit assertion that SSL - and
in particular the RSA based authentication/key exchange - are easily
analysed.   As presented in the current RFC, SSL v3 is just about the 
most complex security protocol I have ever looked at.

In particular, determining whether it is vulnerable to "man in the middle"
attacks is extremely difficult - I'm still not entirely sure whether it is for
cases where the server has no certificate.

The combination of hashing mechanisms, and the way in which they are used 
make it virtually impossible to determine the effects of any properties 
(including weaknesses) inherent in the actual algorithms.

I would very much like to see SSL support different (and simpler) authentication
mechanisms.   Many have already been standardised - X.509 being a notable
example.

Sorry for the rant, but I just couldn't let this one go by...

Cheers,

Michael Warner
Telstra Research Labs

Received on Thursday, 10 October 1996 22:25:01 UTC