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Re: [saag] Further MD5 breaks: Creating a rogue CA certificate

Russ Housley <housley@vigilsec.com> Tue, 30 December 2008 22:30 UTC

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Date: Tue, 30 Dec 2008 17:23:33 -0500
To: Eric Rescorla <ekr@networkresonance.com>
From: Russ Housley <housley@vigilsec.com>
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References: <200812301605.mBUG5cKU027325@raisinbran.srv.cs.cmu.edu> <9535147E88DA266C69B983D0@atlantis.pc.cs.cmu.edu> <p0624081dc5802a331eac@[10.20.30.158]> <20081230213934.C219450822@romeo.rtfm.com> <495A9B44.1010201@mitre.org> <20081230223500.48BD350822@romeo.rtfm.com>
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Subject: Re: [saag] Further MD5 breaks: Creating a rogue CA certificate
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>I'm not sure I understand the issue here, but
>they don't actually have to be totally randomized. You could use a
>PRF so they were predictable to the CA.

That works.  This works too: the serial number could be composed of 
two parts, where the most significant bits are a counter and the 
least significant bits are randomly generated.

Russ 

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