From: Don.Stephenson@Eng.Sun.COM (Don Stephenson)
Date: Sat, 30 Sep 95 23:16:29 PDT
To: ses@tipper.oit.unc.edu
Subject: Re: NetScape's dependence upon RSA down for the count!
Message-ID: <9510010614.AA08538@icenine.Eng.Sun.COM>
MIME-Version: 1.0
Content-Type: text/plain



> From ses@tipper.oit.unc.edu Sat Sep 30 20:43:51 1995

> My currently recommended approach is to enforce the verisign requirement 
> that all valid hostnames for the server be included in the certificate as 
> CN values. This allows the check to be made below the application layer. 
> Unfortunately a lot of currently issued certificates are non-compliant 
> (even Verisign and netscape :-); any fully automated implementation needs 
> a static table of hostnames aliases- interactive applications can 
> display certificates for manual review.

I don't think binding hostnames to certificates helps much because 
both hostnames and IP addresses can be spoofed and DNS servers can be 
subverted.  The important thing is the binding to the "service" name or 
definition (e.g. InterState online banking service).


> This is not really much protection. Getting hold of any key is much 
> easier than getting a specific key, and don't forget there are a number 
> of vulnerable keys floating around until their expiration dates pass. 

Well of course, if the secret key of the server (or worse yet, certificate 
authority) is compromised, all bets are off.  That's true of just about any 
protocol you can dream up.

Are you just referring to the problem of accurate and up to date certificate 
revocation lists (CRL) being available ?

If so, you're right, this is a very difficult problem to solve without 
having a truly reliable and pervasive key-distribution & CRL system 
deployed throughout the world.

- Don