Re: OpenID/Debian PRNG/DNS Cache poisoning advisory

From: Peter Gutmann <pgut001@cs.auckland.ac.nz>
To: dave.korn@artimi.com,ekr@networkresonance.com
Cc: benl@google.com,bugtraq@securityfocus.com,cryptography@metzdowd.com,full-disclosure@lists.grok.org.uk,general@openid.net,security@openid.net
Subject: Re: OpenID/Debian PRNG/DNS Cache poisoning advisory
Date:


Eric Rescorla <ekr@networkresonance.com> writes:

>It's easy to compute all the public keys that will be generated
>by the broken PRNG. The clients could embed that list and refuse
>to accept any certificate containing one of them. So, this
>is distinct from CRLs in that it doesn't require knowing 
>which servers have which cert...

You'd also end up with a rather large list for the client to carry around, 
which would be especially problematic for lightweight clients.  You'd need to 
represent it as something like a Bloom filter to avoid this (given that most 
users will just click OK on invalid certs, the small false positive rate 
shouldn't have much effect either :-).

Peter.





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