Renewing expiring key - done correctly?

[Ingo Klöcker]

On Tuesday 03 December 2013 19:03:13 Robert J. Hansen wrote:
> On 12/3/2013 6:20 PM, Hauke Laging wrote:
> > Imagine a certificate which is always prolonged for just one day. If
> > this gets compromised then it will not be prolonged any more (at
> > least not by its owner but we all love our highly secure offline
> > mainkeys, don't we?) so everyone will notice that within hours.
> 
> 1.  The attacker can just extend the validity himself.  He's
>     successfully compromised the key, after all.
> 
> 2.  As a consequence of #1, no one will notice.

In your quotation you've snipped away too much of Hauke's message. Hauke 
gave two scenarios. In the second scenario

> > b) the key has been compromised and cannot be revoked (because the
> > owner has lost access to the secret mainkey and has neither a
> > revocation certificate nor a (usable) designated revoker)

your assertion is correct.


In the first scenario

> > a) the key has been compromised and revoked and you don't know that
> > (because your last certificate update was before the revocation
> > publishing)

it is incorrect because the attacker cannot extend the validity of the 
revoked key.


Regards,
Ingo
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