Full Disclosure mailing list archives

Re: OpenID/Debian PRNG/DNS Cache poisoning advisory


From: "Ben Laurie" <benl () google com>
Date: Fri, 8 Aug 2008 20:10:41 +0100

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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