> 2 jan 2014 kl. 22:57 skrev Phillip Hallam-Baker <[email protected]>:
> 
> 
> 
> 
>> On Thu, Jan 2, 2014 at 4:00 PM, Leif Johansson <[email protected]> wrote:
>> 
>> 
>> 2 jan 2014 kl. 21:25 skrev Phillip Hallam-Baker <[email protected]>:
>> 
>>>> > Please don't overstate the results of
>>>> > the excellent research that you did; doing so diminishes the
>>>> > research.
>>>> 
>>>> I'm not overstating anything. I think you don't understand what we
>>>> actually did if you think that later, patching things will somehow
>>>> magically stop previously successful attacks...
>>> 
>>> 
>>> You are confusing people by using a valid attack against the algorithm to 
>>> argue against the trust model. PKIX is designed on the assumption that the 
>>> digest algorithm chosen is secure against a second preimage attack.
>> 
>> The fundamental flaw in the pkix trust model is that there is no deployable 
>> mechanism for limiting the impact of such an attack.
>> 
>> That realization should inform future design and that bit is certainly on 
>> topic ;-)
> 
> It is on topic but not limited to PKIX. 
> 
> We have since learned that algorithm agility is not quite the security 
> benefit we once thought as the security of the system is determined by the 
> weakest algorithm you support, not the strongest one you implement.
> 

A trust model based on shorter-time-to-live keys would have limited the impact 
too.


> 
> Problem is that I can't see a way to really control this type of attack 
> without a very considerable cost in usability and I think it would constrain 
> other defenses.
> 
> Anyone using Windows XP in the Enterprise for any purpose other than finding 
> viruses is guilty of security malpractice at this point. It is an obsolete OS 
> that would have been at EOL if lazy sysadmins hadn't begged to keep it.
>  
> 
> My current solution in my email project is to attempt to require SHA512 for 
> all certificates. But I am not sure that is actually sustainable.
> 
> -- 
> Website: http://hallambaker.com/
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