Eric Rescorla wrote on 08 August 2008 17:58: > At Fri, 8 Aug 2008 17:31:15 +0100, > Dave Korn wrote: >> >> Eric Rescorla wrote on 08 August 2008 16:06: >> >>> At Fri, 8 Aug 2008 11:50:59 +0100, >>> Ben Laurie wrote: >>>> However, since the CRLs will almost certainly not be checked, this >>>> means the site will still be vulnerable to attack for the lifetime of >>>> the certificate (and perhaps beyond, depending on user >>>> behaviour). Note that shutting down the site DOES NOT prevent the >>>> attack. >>>> >>>> Therefore mitigation falls to other parties. >>>> >>>> 1. Browsers must check CRLs by default. >>> >>> Isn't this a good argument for blacklisting the keys on the client >>> side? >> >> Isn't that exactly what "Browsers must check CRLs" means in this >> context anyway? What alternative client-side blacklisting mechanism do >> you suggest? > > 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...
<scurries off to read CRL format in RFC> Oh, you can't specify them solely by key, you have to have all the associated metadata. That's annoying, yes, I understand your point now. IIRC various of the vendors' sshd updates released in the immediate wake of the Debian catastrophe do indeed block all the weak keys. cheers, DaveK -- Can't think of a witty .sigline today.... _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.grok.org.uk/full-disclosure-charter.html Hosted and sponsored by Secunia - http://secunia.com/