Re: OpenID/Debian PRNG/DNS Cache poisoning advisory

From: Ben Laurie <benl@google.com>
To: Tim Dierks <tim@dierks.org>
Cc: Dan Kaminsky <dan@doxpara.com>,Eric Rescorla <ekr@networkresonance.com>,Dave Korn <dave.korn@artimi.com>,bugtraq@securityfocus.com,security@openid.net,OpenID List <general@openid.net>,cryptography@metzdowd.com,full-disclosure@lists.grok.org.uk
Subject: Re: OpenID/Debian PRNG/DNS Cache poisoning advisory
Date:


On Fri, Aug 8, 2008 at 7:54 PM, Tim Dierks <tim@dierks.org> wrote:
> Using this Bloom filter calculator:
> http://www.cc.gatech.edu/~manolios/bloom-filters/calculator.html , plus the
> fact that there are 32,768 weak keys for every key type & size, I get
> various sizes of necessary Bloom filter, based on how many key type / sizes
> you want to check and various false positive rates:
>  * 3 key types/sizes with 1e-6 false positive rate: 2826759 bits = 353 KB
>  * 3 key types/sizes with 1e-9 false positive rate: 4240139 bits = 530 KB
>  * 7 key types/sizes with 1e-6 false positive rate: 6595771 bits = 824 KB
>  * 7 key types/sizes with 1e-9 false positive rate: 9893657 bits = 1237 KB
>
> I presume that the first 3 & first 7 key type/sizes in this list
> http://metasploit.com/users/hdm/tools/debian-openssl/ are the best to
> incorporate into the filter.
>
> Is there any chance it would be feasible to get a list of all the weak keys
> that were actually certified by browser-installed CAs, or those weak
> certificates? Presumably, this list would be much smaller and would be more
> effectively distributed in Bloom filter form.

Or as a CRL :-)





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