Excellent summary! :-)
Have you looked at
http://www.cacert.org/ ?
g-)
----- Original Message -----
From: Cesc
To: Klaus Darilion
Cc: serusers(a)iptel.org ; users
openser.org
Sent: Wednesday, October 12, 2005 11:13 AM
Subject: Re: [Users] Re: [Serusers] trusting peers
Hi,
Klaus, i think that you hit the fountain of truth :)
As of now, ser-tls only provides transport layer authentication. Not more. Who is
allowed to authenticate? all those you trust, that is, all those with the cert signed by
the CAs you trust. If you picked a ruthless CA that would give away certs to
hacking.incorporated.com ... sorry :)
Now, for sip message authentication and authorization you need to lift the
authentication information from TLS up to the application (ser). It is not difficult, it
just needs a few lines of code for that (all the certs exchanged are within reach for as
long as the tls connection stays up). Here is where the tls_tools module's functions
(to be written) come into play:
- tls_check_from/to()
- tls_check_cn_trusted()
- ...
So, let's say we want to set up a tls test network (which we do).
We don't want to pay for the certs, so we should generate a root cert (say,
"openser.org"). It would be even better if some nice CA whose cert is signed by
a recognized root would do sign that for us ... anyone with connections? :) This would
ease transition and compatibility issues ...
The root cert provides certs for each domain (
providerX.com,
providerY.net, ... )
Now, we all can authenticate each other.
With the tools for sip authentication and authorization, you can decide who you allow to
do what in your proxy ...
Regards,
Cesc
On 10/12/05, Klaus Darilion <klaus.mailinglists(a)pernau.at> wrote:
Nils Ohlmeier wrote:
Klaus, if you do not trust
badguy.com although he has
a valid singed
certificate from a CA which you trust, then you can throw away TLS
completely.
There is a big difference between authentication and authorization.
1. I have to authenticate the peer. Using TLS and certifiactes is fine.
2. I have to authorize the peer. Some peers will be e.g. routed
different. You would this this like:
if (message is from trusted peer) {
....
So I need to check the certificate in ser.cfg somehow, or associate the
domain in the From header with the domain in the certificate.
Or do I miss the point?
regards
klaus
The hole model only works because the trust in
inherited from the CA when you
get a singed certificate.
If you do not trust any CA, except your own, then you created your own trust
database which is hard to maintain. No matter what is the base of the
trustworthyness (IP; certificate signed by you; shared secret or signed
certificate for IPSec) maintaining the trust database (or however you call
it) is a real pain, that is the reason why you should trust someone else to
do this job.
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