Re: X.509

[Roumen Petrov <openssh%roumenpetrov.info@localhost>]

Peter Gutmann wrote:
> Oskari Saarenmaa <oskari%saarenmaa.fi@localhost> writes:
>
>   
> > I recently submitted a new individual draft for ssh x509 which backs down
> >     
> >from what we specified in the latest WG draft, and just specifies how we use
>   
> > certificates in our implementations.  It's available at
> > http://tools.ietf.org/wg/secsh/draft-saarenmaa-ssh-x509-00.txt
> >
> > Any thoughts?
> >     
>
> Further to my previous comments, the text in the Implementation Considerations
> section seems a bit misplaced.  Firstly, it's already subsumed by the "refer
> to PKI standards" requirement in the Security Considerations, so it's
> redundant.  Secondly, I would both hope that any implementation that doesn't
> implement a verification algorithm would fail to verify the certificate that
> uses it, and can't really see why this would be singled out for special
> attention when there are lots of other things that also need to be checked.
>   

It is possible simple implementation to compare public key extracted from
certificate sent with keys from its configuration and if they match to 
accept
connection. As example without this self-issued(self-signed) X.509 
certificates
cannot be used in authentication.

> Finally, to be nit-picky, you need to verify up to a trust anchor, which isn't
> necessarily "all the certificates in the chain".
>   
Yes verification should be described in RFC3280. Only the direction is 
opposite -
valid path (chain) start from trust anchor .

> For all of the above, the appropriate solution seems to be to remove this
> section, since it's already more than covered by the requirement in section 7.
>
> Is anyone running a test SSH server that implements this authentication
> mechanism?  I'd like to have something to test against...
>
> Peter.
>   

You can test my implementation based on openssh and diff files
on http://roumenpetrov.info/openssh/download.html .

Check the options X509KeyAlgorithm and may be KeyAllowSelfIssued.

The configuration like this:
 X509KeyAlgorithm x509v3-sign-rsa,rsa-sha1,ssh-rsa
 X509KeyAlgorithm x509v3-sign-dss,dss-raw,ssh-dss
, should be in conformance with draft.

The configuration:
 X509KeyAlgorithm x509v3-sign-rsa,rsa-sha1
 X509KeyAlgorithm x509v3-sign-dss,dss-raw
, should be used with ssh.com, f-secure.com (etc. ?) .
I think that ssh.com and f-secure.com will accept md5 hash (rsa based 
cert.),
but not in default configuration.


The default is compatible with openssh, vandyke.com (etc. ?) .


Roumen