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full-disclosure-uk: Re: [Full-disclosure] OpenID/Debian PRNG/DNS

Re: [Full-disclosure] OpenID/Debian PRNG/DNS Cache poisoning advisory

From: Forrest J. Cavalier III <mibsoft_at_nospam>
Date: Sat Aug 09 2008 - 01:37:44 GMT
To: Eric Rescorla <ekr@networkresonance.com>


Eric Rescorla wrote:
>
> To be concrete, we have 2^15 distinct keys, so, the
> probability of a false positive becomes (2^15)/(2^b)=2^(b-15).
> To get that probability below 1 billion, b+15 >= 30, so
> you need about 45 bits. I chose 64 because it seemed to me
> that a false positive probability of 2^{-48} or so was better.
>
> -Ekr

Since it's a known set, I think you can use perfect hashing. There will still be false positives, but presumably no "bad" keys, nor keys matching the hash everyone agrees on, are going to be issued after today, right?

Yeah, right.



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